ZA200601328B - Hydrophobic composites and particulates and applications thereof - Google Patents

Description

HYDROPHOBIC COMPOSITES AND PARTICULATES AND APPLICATIONS

THEREOF

FIELD AND BACKGROUND OF THE INVENTION :

The present invention relates to hydropshobic composites, particulates and freze- flowing aggregates, methods of producing same, and applications thereof. Moamre particularly, the present invention relates to hydrophobic composites having a core material coated by a hydrophobic powder haviing an impure element pre-treated witta a : hydrophobic hydrocarbon, and optionally with additional coating agents, such that the resulting composites are characterized by superior water-repellency and durability, suitable for various applications. The present invention further related to hydrophotbic composites that are prepared in aqueous soluti ons.

In many applications it is desired to prevent moisture from reaching criti-cal regions using hydrophobic materials which repel water. In the area of ciivil engineering, when water percolate into constsruction, salts and minerals present in Tthe water damage the concrete (or other material s from which the construction is made), and causes corrosion and deformation to its reinforcing steel bars or wire fabric. Stach . corrosion and deformation leads to the appearance of crakes in the concrete amd, eventually, to a local reduction of construction strength. Other internal objects, stich as pipes, electrical wires, communication chaxnels and the like may also be damage: by moisture.

The presence of water in the house iss associated with numerous of unpleassant evidences such as, moisture at the base of tthe walls, under carpeting or under flecor tiles; rust at the base of steel posts; stains, discoloration or decay of wood, paneli_ng, drywall and other objects close to the floor, walls or ceiling; molds and mildew on concrete, furnishings or carpets; efflorescemce ("white powder") on the concreete; peeled floor tiles; damp odor; "sweating" walls (condensation of excessive humidity); condensation of water on windows; plugged or damaged rain gutters; growth of m_oss and the like. 0

Moisture may percolate into the corastruction, either vertically, for exanmple because of accumulation of water on roofs or floors of construction/foundations_, or horizontally, by leakage of water through external walls of a building for example, because of extreme weather conditions, A sever problem of horizontal leakage iss in buried walls or portions thereof, where hwdrostatic pressure generated by excess

: moisture in the surrounding soil pushing in on the outside of th-e foundation wall, significantly contributes to horizontal leakage.

The percolation of moisture through concrete walls is explained by the porosity : of the concrete (about 12 % - 20 %), formed during the curing process when surplus water creates a network of interconnected capillaries, about 10-100 -nm in diameter.

As used herein, the term about refers to + 10 %.

These capillaries contribute to the percolation of moistures there through via ) capillary forces. As the concrete ages, the water percolation, gradumally leaches out the concrete and makes it more and more porous.

Another problem caused by moisture is mildew, which, apart from being : unaesthetic, creates a musty odor. Even though a substantial amount of standing water may be removed by prior art waterproofing methods that utilize a drainage conduit, residual moisture will still cause mildew problems. It is recogniz=ed that a prolonged exposure to mildew may cause many health problems, such as, all ergies, asthma, skin diseases and the like.

Basement is by far the largest source of moisture in a ho—use. Covered floor ~ and walls in the finished basement trap moisture and eventually cause damp or wet basement. As the pH level of the concrete is high, the alkalis pre=sent in the concrete dissolved by the water and attack paints and floor tiles. Hence, even if the basement looks dry, moisture is pouring in by seeping through capillaries. The mildew, which is typically initiated in the basement due to its excessive amount of nmoisture, may spread to other areas of the house above ground, e.g., by ventilation.

In many countries sand is used as a bed under the floor tiles and is recommended by standards in order to reduce noise. Water, origirating from periodic cleaning pluming leakage or heavy rain (e.g., in tiled roofs) gesnerate a substantial amount of excessive weight, up to approximately 100 Kilograms of water per square meter. Large portion of the water is trapped under the tiles and thme sand thus remains -. 3 wet for many years. Such excessive weight is typically taken uncler consideration by : : the engineer in the planning stages of the building, which, in o rder to increase the strength to the construction, uses more concrete and reinforcings material under the sand bed. The contribution of the water and construction extra strengthening to the . . overall weight accelerates the sinking of the building. The problerm is only aggravated in hanging structures such ass balconies and overpasses, interconnecting different parts of buildings.

In addition to its excessive weight, the wet sand under the tiles attracsts insects, ) "such as ants, warms, aphids, dust mites and the like. Apart from the recogni sed health oo s problems associated with suach attraction, the insects excavate through the sand and accelerate sinking of the tiles.

Being wet most of the time, the sand under the floor tiles becomes a thermal conductor, thus reducing an isolation pretended to be achieved in the desig stages of the building. In some buildings, an electrical heating system is constructed under the } 10 floor. The contact between these systems and the wet sand may cause a sever damage to the system, or, in extremes cases, even fire may occur.

With respect to under floor waterproofing of balconies or tiled roof=s, all prior art methods are directed at positioning a waterproofing material such as= a sealing sheet, a bituminous membrane or a solvent based elastomeric coat, under thee bed sand supporting the floor tiles. However, almost irrespectively of their quality, tthe life time of these waterproofing materials is not sufficient, because of the salts containing moisture being present in the sand.

Even in constructiomas or part of constructions where sand is not in contact with the waterproofing material, the life time of prior art materials is limited. Alkalis dissolved in the water attack paints and adhesives and damage the waterproofing material, by formation of cracks, peels or blisters.

An additional indoors problem related to sealing means is the pwroblem of elevated levels of Radon gas which may be found in houses, typicallzy, but not exclusively, in the lower prarts thereof, e.g., basements. Radon is an invisible and 25. odourless radioactive gas, produced by the decay of radioactive heavy meta 1s uranium and thorium, dispersed tlaroughout the Earth's crust. The by-products of the : radioactive decay of these metals are lighter radioactive heavy metals which also decay into lighter metals arad so on. The decay chain continuously produc=es radium, which decays into radon isotopes, mainly Radon-222 and Radon-220 (the latter also known as Thoron), where the Radon-222 isotope is the most common indoors radioactive gas.

Radon decay producsts are tiny radioactive solid particles which floa_t in the air and, breathed by human, get trapped in the lungs, trachea and bronchi. Because of

} these decay products, the Radora, at the levels common in homes, is about 1,000 tim_es more lethal than the safety limitss on any other toxin or carcinogen.

Being the heaviest knowwn gas (nine times heavier than air), the Radon g=as naturally moves into the pemmeable soil and the gravel bed surrounding tThe foundations of the house and subsequently diffusively penetrates into the houmse through the above mentioned Openings and pores in concrete. Radon is soluble in water and therefore carried to ®he vicinity of the house by underground streams, and "+ further into the house by the percolation of water, e.g., through the concrete. The meost * common carrier of Radon into tthe house is water. : 0 Moisture and water also cause damage to buried objects, such as undergroumnd pipes, storage tanks (e.g., gas tanks), tunnels and cables. Due to moisture, corrosion caused by electrolysis, digesting materials, insects and/or micro organisms present- in the sand, many buried objects are exposed to damaging processes which reduce #the lifetime of the objects. In casess where the buried object contains hazardous materi als any leakage there from may hasve severe environmental consequences.

In the area of electric p ower industry, numerous research programs have been

E conducted to identify mechanisms which are responsible for the premature failure- of underground electrical or com-munication cables. It is recognized that many of the premature cable failures are linked to internal build-up of micro sized water branclhes within imperfections of the inswilating layers of the cable, also known as "water tree=s." . The water filled imperfections branch radially inward through the amorphous insulating materials. As the water progresses radially inward the potential for ca~ble failure increases.

Even when the conduecting core of the cable is coated by a sophistica=ted material such as a liquid crystal polymer, the formation of imperfections is inevita_ble due to corrosion caused by electrolysis, digesting materials, insects and/or mie=cro organisms present underground.

Buried pipes and electrical or communication channels are often positiormed inside hollow underground tuloes. The hollow tubes also ease access to the buried object, for maintenance purposses. However, water or other liquids occasionally fand the way into the space betwesen the buried object and the internal surface of the surrounding tube (e.g., throughm holes or cracks formed in the external surfaces of —the tubes, cor through the gap between contacting tubess). The water flows through the tube ~ and caumses damages to the buried objects or to conamection boxes at the end of the tube. "The combination of moisture and sand termds to harden or freeze. The formed hard m_aterial is known to transform axial stresse s from the surrounding environment 5s to the buried object. When the level of the axial stresses exceeds the object's characteristic strength, the object is damaged. To- prevent the above axial stresses, the objects: sre made stronger and/or being buried de=ep into the ground. It is recognized, however, that the cost of positioning objects und- erground increases with the depth im which these objects are to be buried. Moreover, Cleep buried objects are difficult to be accessed, e.g., for maintenance or replacement.

One way to protect an underground object— tube is by applying a sealing coat om "the object or its surrounding tube, so as to preven_t the above agents from damaging its + external surface. However, although in generzal such coats survive the attack o»f digesting materials or organisms, very often loceal damages to the coat arc inevitabl € (for exzample due to axial stresses), which local damages are sufficient to initiate thie erosion of the object. ‘

Generally, moisture can be prevented frorm reaching critical regions by the use of hydirophobic materials which repel water. Deesign considerations for hydrophobi ¢ "© materizals depend on the application for which such materials are designated, an d includee water intrusion pressure, thickness,., chemical compatibility, airflow, temperature compatibility and the like. Water intrusion pressure is a measure of a criticall pressure under which water are forced through the hydrophobic material.

Chemi_cal compatibility is important in applications where the hydrophobic material comes in contact with corrosive material.

Another structure for which waterproofsing is required is a water reservoir, . where the base and the walls thereof need to bes impermeable so as to prevent water

J . from l.eaking out. The problem of leaking resemrvoir is crucial in arid regions wher—e : one de=sire to maintain the content of the reservoir for as much as time possible. : A typical reservoir is a flat area surroumnded by a sloping embankment. In many prior art waterproofing methods, the botto-m of the reservoir (both the flat basse and thee sloping embankment) are covered with ssealing sheets (typically made of higch . densitsy polyethylene, HDPE), adhered or weldec to each other. This method suffemrs from rmany drawbacks. First, because the waterproofing is by a plurality of bonde=d sealing sheets, thhere are many areas near the connection between two adjacent sheets where the bondlling is damaged or mot perfect, and the sheets becosme permeable.

Second, due to its limited elasticity, the sealing sheet tends to be damaged by hard objects, being imn contact therewith either from above or from below.. Third, during maintenance, w-hen the bottom of the reservoir is cleaned by ligh—t machinery or manually, the sezaling sheets may be ruptured. Forth, forces induce esarth movements or cracks formation (e.g., in a man made concrete reservoir) rupture thee sealing sheets.

An additional 1#mitation of prior art method is originated by colonies of insects and organisms prese=nt under the sealing sheets. In which case purificatio -n chemicals are required to puriXy the content of the reservoir.

Waterpreoofing is often required also in agriculture or geardening where irrigation is employed. When an area is artificially irrigated by water, «only a relatively small portion o=f water reach the plants growing on the soil. Most of ~ the water seeps through the eamrth or evaporates. The need to save water is also —xelated to other agricultural prosblems, such as salty soil and underground salty wa ter. Generally, : when designings an area for gardening or for industrial agriculture use,., it is difficult to provide the plait a sufficient amount of water without causing rottenne=ss, while, at the . same time, prev-enting hazardous materials (such as salts) from damaging the roots.

Design econsiderations for hydrophobic materials to be used foor waterproofing any of the above structures include water intrusion pressure, thiclBlikness, chemical compatibility, airflow, temperature compatibility and the like. “Water intrusion pressure is a meeasure of a critical pressure under which water are for—ced through the hydrophobic maaterial. Chemical compatibility is important in appliceations where the hydrophobic material comes in contact with corrosive material.

Over thme years, numerous hydrophobic materials have b-een developed, including PTFE, nylon, glass fibers, polyethersulfone and agg=regates having . hydrophobic properties.

One such material is disclosed in U.S. Patent No. 3,562,153, to Tully et al.

The oil absorbesnt compositions of the Tully et al. patent are obtaine=d by treating a liquid absorben® material, which may be particulate, granular or fibrouss in nature, with a colloidal metzal or metalloid oxide which is chemically bonded to aan organosilicon : compound to reender the metal or metalloid oxide hydrophobic. The hydrophobic ~~ oxide-treated absorbent composition is contacted with the oil-contami=nated water and selectively removes the oil therefrom. The oil absorbenst composition of Tully et al. is . reported to haves excellent water repellency, thus emmabling it to maintain its oil absorbent efficiemncy for long immersion periods. ~ U.S. Pate=nt No. 4,474,852, to Craig, which is imcorporated by reference as if fully set forth huerein, combines ideas of several priomr art patents (US Patent Nos. 3,567,492, 3,6722,945, 3,973,510, 3,980,566, 4,148,941 and 4,256,501, the contents of all of which are hereby incorporated by reference). Ac=cording to Craig, hydrophobic composites having superior water repellency are olotainable by depositing on a particulate and granular core material an adherent first coat which comprises a film- forming polyure=thane and asphalt, as an optional addi tive, and applying to the thus coated core material a second coat comprising a hydrophobic colloidal oxide such as, for example, hy=drophobic fumed silica. Craig teachees that the adherent first coat should not exce=ed 1 weight percentage of the total dmry aggregate weight while the second coat is beetween 0.025 and 0.25 weight percentagee of this total weight. Further according to the= teachings of Craig, hydrophobic composites prepared in this manner not only prevernt water from adhering to the surface.s of the individual composite particles, but also from entering the interstitial spa-ces of the aggregates of the composites.

WO 03/044124, which is also incorporated by reference as if fully set forth herein, also discloses a method of preparing hydrophobic aggregates, which is based on the teachingss of Craig (U.S. Patent No. 4,474,852). According to the teachings of

WO 03/044124,, the hydrophobic aggregates disclosed in U.S. Patent No. 4,474,852 are not satisfactory as they do not withstand water pressure higher than 2-3 centimeters. ’

In a search for a method of producing hydropheobic aggregates with improved water-repellency~ and oil absorbency performance ard improved durability under higher water peressures, it was concluded, accordimg to the teachings of WO 03/044124, tha® an improved method of preparings hydrophobic aggregates, as compared with the teachings of Craig, should include changes relating to the compositions of the first and second coat and the relative amounts thereof, to the © temperature in tThe various process steps and to the miixing rate during the course of : preparation.

Hence, the method disclosed in WC 03/044124 includes depositing on a particulate or granulate core material an adherent first coat which comprises a film- + forming agent such as polyurethane and opstionally a gluing agent such as liquid : asphalt, and applying to the thus coated core mnaterial a second coat which comprises a hydrophobic fumed silicate or any other supemrhydrophobic powder. According to the © teachings of WO 03/044124, the adherent first coat constitutes about 1-2 weight percentages of the total dry aggregate weight: while the second coat constitutes more . than 5 weight percentages of this total weigh t. Further according to the teachings of © WO 03/044124, such hydrophobic aggregate is capable of holding a water pressure of upto 20-30 cm.

Although WO 03/044124 teaches the use of superhydrophobic powders other than hydrophobic fumed silica, this reference= neither specifies nor exemplifies such a - superhydrophobic powder. This reference al so fails to demonstrate any performance of the hydrophobic aggregates disclosed thereein with regard to both, water repellency 5 and its behavior under high water pressures. Furthermore, it is well known in the art that using such a large amount of hydrophobic fumed silica as the second coat, as taught by WO 03/044124, reduces the cost-effectiveness as well as the simplicity of the process. : In addition, as hydrophobic fumed sil ica, as well as other metal oxides treated with organosilicon compounds, such as thwose disclosed in the Craig patent, are characterized as acidic substances, aggregates coated by such materials are susceptible oo to reactions with alkaline reagents such as d_etergents. This feature limits the use of © such aggregates in applications where detergents may be in contact with the hydrophobic aggregates, such as, for examples, top-coatings of various surfaces.

US Patent 4,474,852 mentioned hereinabove describes several applications for oo ts hydrophobic composites in waterproofing applications. Mainly as a top coat on paved surfaces, such as asphalt or concrete, aa flood coat of asphalt sealer should first be applied over the surface, immediately aftesr which a heavy coat of the hydrophobic ’ composites may be sprayed over and rolleed into the asphalt sealer, providing a watertight top coat. The same top coating technique may be used in pothole repairs in roadways.

The composites may also be used a.s a substitute for common aggregate in asphalt roofing or shingles, or in built-usp roofing. In such applications, the hydrophobic composites are effective in preventing water penetration and resultimg damage caused by freeze-thaw cycles as “well as dimensional changes due to wettirg and drying. US Patent 4,474,852 also claims utility as a top coat on paved surfaces, such as asphalt or concrete road surfaces or bridge decking, providing a water-tight finish, which substantially reduces freeze>-thaw damage, and which is unaffected boy salt compositions normally used for ice removal. In addition, these hydrophobwic composites may be applied to painted surfaces to provide a durable, waterproof fini sh over wood, metal, concrete, stone, brick and certain synthetic substrates. Su-ch hydrophobic composites may also be blended with suitable binding agents to provide a water-repellent coat.

As the American Concrete Institute (ACI) recommends a 3-inch pervious sa-md bed spread on top of waterproofing sheet under the building, the hydrophobic composite of US Patent 4,474,852 may also be used as a waterproofing agent in pavement construction, as a fill or bed material under concrete slabs or as a gravel #ill

A5 or ballast for road beds or sidewalks. Elowever, as will be appreciate by a skilled artisan, free-flowing aggregate are made of extremely small particulates hence bei ng easily carried in the wind and washed out by running water. Therefore, without ~ specific and enabling instructions, it woulld be very difficult and probably not practiecal to use the hydrophobic aggregate in its flowing form. 20 Furthermore, presently known methods of producing hydrophobic composi- tes do not result in satisfactory products and are limited by other parameters, such as, for example, cost effectiveness.

There is thus a widely recogmized need for, and it would be highly advantageous to have hydrophobic «composites, particulates and free-flowing = aggregates, methods of producing same and applications thereof, devoid the above ) limitations. . SUMMARY OF THE INVENTION

While conceiving the present iravention, it was envisioned that by further changing the constituents of the first and second coats and the relative amounts } thereof, cost-efficient hydrophobic composites with improved physical and chemi- cal performances would be obtainable. Particularly, it was hypothesized that by using ass a coat a hydrophobic powder comprised of impure elements that have been pre-treatted

3 WO 2005/005566 PCT/IL2004/000635 with @ hydrocarbon such as a long-chain fatty acid (e.g., stearic acid), hydrophobic composites with improved performance would be cost-efficiently obtainable.

While reducing the present in-vention to practice, it was indeed found that by - using the hydrophobic powder described above, hydrophobic composites having superior physical and chemical performances as compared with the presently known hydrophobic composites were obtainesd. These newly disclosed composites comprise oo a hydrophobic coating which constitiates not more than 5 weight percentages of the : total weight of the composite and aree characterized by superb water-repellency and - other beneficial properties, as is detaileed hereinbelow.

Hence, according to one aspe=ct of the present invention there is provided a hydrophobic composite comprising a core material coated by a hydrophobic powder, the hydrophobic powder comprises at least one impure element having a hydrocarbon chain attached thereto. }

According to further features in preferred embodiments of the invention 1S described below, the element is selexcted from the group consisting of a metallic element, a semi-metallic element and a= transition metallic element. - According to still further featu res in the described preferred embodiments the hydrophobic powder is bonded to the ¢ ore material via an adherent layer.

According to still further featuzres in the described preferred embodiments the hydrophobic composite further compmrising at least one additive selected from the group consisting of a coloring agent, == UV resistant agent, a bleaching agent and an abrasive agent.

According to still further featur—es in the described preferred embodiments the coloring agent constitutes between about 0.1 and about 2 weight percentages of the 2s hydrophobic composite.

According to still further featur—es in the described preferred embodiments the

UV resistant agent and the bleaching agent each constitutes between about 0.01 and about 2 weight percentages of the hydrophobic composite.

According to still further features in the described preferred embodiments the ’ abrasive agent constitutes between abowat 0.1 and about 0.5 weight percentages of the . hydrophobic composite.

According to another aspect o f the present invention there is provided a method of preparing a hydrophobic cormposite, the method comprising coating a core material with a hydrophobic powder, the hydrophobic powder comprises at least one impure clement having a hydrocarbon chain attached thereto, to thereby provide the hydrophobic composite.

According to further features in preferred embodiments of the invention described below, the method further comprising. prior to the coating, applying onto the cor-e material an adherent layer, the adheraent layer bonding the hydroplaobic powder to the core material.

According to still further features in the clescribed preferred embodiments the step of applying onto the core material an adherert layer comprises admixing the core material with an adherent mixture containing a. film-forming agent and a volatile solvent, while removing all of the volatile sol*vent from the mixture of the core =. material and the adherent mixture, to thereby provide the core material having applied thereon the adherent layer. “According to still further features in the described preferred embodiments the 1S step of sapplying onto the core material an adherermt layer comprises admixing the core materiall with an aqueous adherent mixture contaimning a water-based gluing agent and an aqueous solvent (e.g., water), while removing all of the aqueous solvent frome the mixture of the core material and the adherent mixture, to thereby provide the «ore material having applied thereon the adherent layer.

According to still further features in the described preferred embodiments the method further comprising drying the core material prior to the coating.

According to still further features in the described preferred embodiments the method further comprising drying the core material prior to the admixing.

According to still further features in the de=scribed preferred embodiments the method further comprising, after the coating, curing the hydrophobic composite.

According to still further features in the de=scribed preferred embodiments the volatile ssolvent is an organic solvent having a bowiling temperature ranging between about 80 °C and about 200 °C.

A_ccording to still further features in the de.scribed preferred embodiments the method further comprising, prior to the coating, admixing the core material with an additive sselected from the group consisting of a coloring agent, a UV resistant agent, a bleachings agent and an abrasive agent.

According to still further features in the described preferred embodim: ents the method furthex comprising, prior to the coating, admixing the core material having thereon the acdkherent layer with an additive selected from the group consisting of a coloring agent., a UV resistant agent, a bleaching agent and an abrasive agent.

According to still further features in the described preferred embodim ents the core material is selected from the group consisting of a particulate materieml and a granulate material.

According to still further features in the described preferred embodiments the core material is selected from the group consisting of sand, gravel, slag, pomrcelanit, dolomite, porcelain, basalt, quartz sand, coal ash, chalk, zeolite, montmorillonite, agapultite, flint, bentonite, perlite, mica, wood chips, nut shells, sawdwist and combinations thereof.

According to still further features in the described preferred embodiments the core material thas an average particle size ranging between 25 millimeters and 5 microns.

According to still further features in the described preferred embodimeents the core material is quartz sand. © According to still further features in the described preferred embodiments the adherent layer constitutes between about 0.5 and about 7 weight percentagess of the hydrophobic composite.

According to still further features in the described preferred embodiments the hydrophobic powder constitutes between about 0.1 and about 5 weight percentaages of the hydrophobic composite.

Accordimg to yet another aspect of the present invention there is provided a hydrophobic particulate comprising a particulated core material coated by a hydrophobic powder, the hydrophobic powder comprises at least one impure e ement having a hydrocarbon chain attached thereto.

According to further features in preferred embodiments of the invention described below, the hydrocarbon chain comprises at least 10 carbon atoms.

According to still further features in the described preferred embodimernts the hydrocarbon is a residue of a fatty acid having at least 12 carbon atoms.

Pp According to still further features in the described preferred embodiments the fatty acid is selected from the group consisting of stearic acid, lauric acid, myristic acid, palmitic acid, oleic acicl, linolenic acid and arachidonic acid.

According to still fumrther features in the described preferred embodiments the at least one element is sele=cted from the group consisting of a metallic clement, a semi-metallic element, a trarsition metallic element and combinations thereof.

According to still further features in the described preferred em_bodiments the at least one element is selected from the group consisting of magnesium, calcium, aluminum, zinc, sodium, barium, zirconium, manganese, titaniurm, vanadium, chromium, iron and combinations thereof. - According to still fuerther features in the described preferred emmbodiments the

B hydrophobic composite ancl particulate are characterized as being iractive toward alkaline reagents. - According to still fumrther features in the described preferred emrabodiments the 5 hydrophobic composite and particulate is capable of preventing water adherence © thereto and water penetrati-on therein under an external pressure of up to about 4.5 "atmospheres. : According to still fumrther features in the described preferred embodiments the hydrophobic composite andl particulate is characterized by being durable to dynamic water wear for at least 2 moths.

According to still fuarther features in the described preferred embodiments the gluing agent constitutes bestween about 0.1 and about 50 weight percsentages of the adherent layer.

According to still fiarther features in the described preferred embodiments the 35 hydrophobic particulate fumther comprising at least one additive selected from the group consisting of a coloring agent, a UV resistant agent, a bleachingg agent and an abrasive agent. : According to still farther features in the described preferred embodiments the ) coloring agent constitutes between about 0.1 and about 2 weight percentages of the hydrophobic particulate.

According to still foarther features in the described preferred enmibodiments the

UV resistant agent and the bleaching agent each constitutes between mbout 0.01 and about 2 weight percentages of the hydrophobic particulate.

According to still further features in the described preferred embodiments the abrasive agent constitutes between about 0.1 and about 0.5 weight percentages of the hydrophobic particulate.

According to still another aspect of the present in=vention there is provided a method of preparing a hydrophobic particulate, the met-hod comprising coating a particulated core material with a hydrophobic powder, the hydrophobic powder comprises at least one impure element having a hydrocarbo-n chain attached thereto, to thereby provide the hydrophobic particulate.

According to further features in preferred embowdiments of the invention described below, the method further comprising, prior to —the coating, applying onto the particulated core material an adherent layer, the adherent layer bonding the hydrophobic powder to the particulated core material.

According to still further features in the described preferred embodiments the step of applying onto the particulated core material an adherent layer comprises admixing the particulated core material with an adherent rmixture containing a film- forming agent and a volatile solvent, while removing all off the volatile solvent from the mixture of the particulated core matcrial and the adh erent mixture, to thereby a provide the particulated core material having applied thereon_ the adherent layer.

According to still further features in the described preferred embodiments the step of applying onto the particulated core material an eadherent layer comprises admixing the particulated core material with an aqueous adherent mixture containing a water-based gluing agent and an aqueous solvent (e.g., wate=r), while removing all of the aqueous solvent from the mixture of the particulated core material and the adherent mixture, to thereby provide the particulated core material heaving applied thereon the adherent layer.

According to still further features in the described preeferred embodiments the method further comprising drying the particulated core materizal prior to the coating.

According to still further features in the described preferred embodiments the - method further comprising drying the particulated core materi=al prior to the admixing,

According to still further features in the described preferred embodiments the ’ method further comprising, after the coating, curing the hydrophobic particulate.

According to still further features in the described pre=ferred embodiments the : curing is performed for a time period ranging between 1 and 30 days.

According to still further featumres in the described preferred embodiments the removing of the volatile solvent is perfcormed by evaporative heating.

According to still further featusres in the described preferred embodiments the removing of the volatile solvent is performed at room temperature.

According to still further featur—es in the described preferred embodiments the volatile solvent is an organic solvent Fhaving a boiling temperature ranging between oo about 80 °C and 200 °C.

According to still further features in the described preferred embodizments the method further comprising, prior to the coating, admixing the particul=ated core - 1© material with an additive selected from the group consisting of a coloring ageent, a UV resistant agent, a bleaching agent and arm abrasive agent.

A According to still further featuress in the described preferred embodirmenis the method further comprising, prior to the coating, admixing the particuleated core material having thereon the adherent lemyer with an additive selected from the group 1S consisting of a coloring agent, a UV resistant agent, a bleaching agent and an_ abrasive agent, ) According to still further featuress in the described preferred embodiments the ’ particulated core material has an averages particle size ranging between 25 millimeters and 5 microns.

EOE According to still further features in the described preferred embodinents the oo particulated core material is quartz sand.

According to still further features in the described preferred embodiments the film forming agent is a film forming polyurethane.

According to still further features in the described preferred embodim_ents the adherent mixture further comprises a gluiang agent.’ : : According to still further features. in the described preferred embodimeents the gluing agent is a volatile hydrocarbon hav~ing at least 12 carbon atoms.

According to still further features in the described preferred embodime=nts the gluing agent is selected from the group consisting of liquid asphalt, paraffin wax, beeswax, lanolin wax, linseed oil and com_binations thereof.

According to still further features in the described preferred embodiments the hydrophobic powder has an average particsle size ranging between 0.02 micron and 50 : microns.

Accordirg to still further features in the described preferred embodiments the hydrophobic powder has a surface area ranging between 1 m%/gram a-nd 60 m’/gram.

Accordirg to still further features in the described preferred embodiments the hydrophobic furmed silica constitutes between 1 and 99 weight p ercentages of the hydrophobic powder.

Accordimmg to still further features in the described preferred embodiments the adherent layer c=onstitutes between about 0.5 and about 7 weight percentages of the hydrophobic particulate.

Accordinag to still further features in the described preferred embodiments the hydrophobic povevder constitutes between about 0.1 and about 5 weig=ht percentages of the hydrophobic particulate.

While fumrther conceiving the present invention, it was envisiconed that efficient hydrophobic cormposites, including hydrophobic particulates and h-ydrophobic free- - flowing aggregattes, can be prepared by coating a core material witth a hydrophobic material that is “bonded thereto via a water-based adherent layer, thus avoiding the disadvantageous use of organic film-forming agents and gluing agents.

While rec@ucing the present invention to practice, it was furthe.r found that cost- efficient, safely-porepared and environmentally friendly hydrophobic ceomposites can be easily prepared b—y using a water-adherent layer that bonds the hydrophobic material to the core material, while still achieving the desired characteristics of the resulting . composites.

Thus, according to still another aspect of the present inwwention there is provided a hydrophobic composite comprising a core material coated by a © hydrophobic material bonded tehreof via a water-based adherent layer.

Accordings to further features in preferred embodiments of the invention . described below, sthe water-based adherent layer comprises a water-bassed gluing agent.

According to still further features in the described preferred esmbodiments the "water-based ghuin_g agent is a bitumen-latex paste.

According to still further features in the described preferred embodiments the '30 hydrophobic mate=rial is selected from the group consisting of a hydrcophobic powder comprising at leasst one impure element having a hydrocarbon chain amttached thereto, hydrophobic fume=d silica, molten polypropylene and any mixture thereof.

The hydrophobic composite, the core material and the hydrophobic powde=t, are as described hereinabove.

According to yet another aspect of thee present invention there is provided a method preparing the hydrophobic composite described above, which comprises admixing a core material and an aqueous adkerent mixture including a water-base=d gluing agent and an aqueous solvent; remov-ing the aqueous solvent to thereby sto thereby provide the core material having applied thereon the water-based adheremnt _ layer; and coating the core material having applied thereon the water-based adheremnt layer with the hydrophobic material, thereby providing the hydrophobic composite.

According to further features in preferred embodiments of the invention described below, the concentration of the water-based gluing agent in the aqueoras adherent mixture ranges between about 1 weight percentage and about 99 weight percentages.

According to still further features in thae described preferred embodiments tine method further comprises drying the core material prior to the admixing.

According to still further features in thae described preferred embodiments tine "method further comprises drying the core material having applied thercon the wate—x- based adherent layer prior to the coating.

According to still further features in tkme described preferred embodiments tine method further comprises, after the coating, cusring the hydrophobic composite.

According to still further features in thee described preferred embodiments the curing is performed for a time period ranging b etween 1 and 30 days.

According to still further features in thxe described preferred embodiments thme removing the aqueous solvent is performed by fumble drying.

According to still further features in th e described preferred embodiments thae method further comprises, prior to the coatirag, admixing the core material havin _g thereon the water-based adherent layer with an additive selected from the grou-p consisting of a coloring agent, a UV resistant a gent, a bleaching agent and an abrasiv—e agent.

According to an additional aspect of thxe present invention there is provided a free-flowing hydrophobic aggregate capable of repelling a predetermined maximaal pressure of liquid, the free-flowing hydrophobwic aggregate comprising a plurality oef differently sized particulates, wherein at least one of a size distribution of thee particulates, a contact angle between the liquid and fhe particulates and a characteristic distance between adjacent particulates is selected so that when a layer of the free- flowing hydrophobic aggregate is in contact with a Riquid having a pressure lower than _ or equal to the predetermined maximal pressure, percolation of the liquid through the free-flowing hydrophobic aggregate is prevented. : According to further features in preferread embodiments of the invention described below, the layer has a thickness from about 1 em to about 10 cm and further wherein the predetermined maximal pressure is equivalent to a column of water having a height above 100 cm.

According to still further features in the described preferred embodiments the free-flowing hydrophobic aggregate further comprising inflatable particulates size wise compatible with capillaries formed betweer the particulates and capable of absorbing the liquid.

According to still further features in the d escribed preferred embodiments a 15 . freezing temperature of the inflatable particulates below about —20 degrees centigrade, both in an inflated state and in a deflated state of thes inflatable particulates.

According to still further features in the described preferred embodiments the size distribution is selected so that the free-flowing hydrophobic aggregate is characterized by a minimal water absorption capability.

According to still further features in the desscribed preferred embodiments the predetermined thermal properties are selected frorm the group consisting of thermal conductivity, specific heat capacity and latent heat.

According to still further features in the desscribed preferred embodiments the size distribution is selected so that the free-flowing hydrophobic aggregate is capable of allowing evaporation of the liquid.

According to still further features in the described preferred embodiments the size distribution is proportional to the predetermined maximal pressure.

According to still further features in the deescribed preferred embodiments a cosine of the contact angle is proportional to the predetermined maximal pressure, the contact angle is measured from a tangent to a surface defined by the free-flowing - hydrophobic aggregate. :

According to still further features in the described preferred embodiments the oo characteristic distance is inversely proportional to the predetermined maximal ‘ pressure. . According to still further features in the described preferred embodiments the "5 plural ity of differently sized particulates comprises a particulated core material coated by a lmydrophobic powder selected so as to provide the contact angle.

According to still further features in the described preferred embodiments the hydrosphobic powder comprises inflatable particulates capable of absorbing the fluid.

According to still further features in the described preferred embodiments a diameter of the inflatable particulates is from about 1 micrometer to about 100 : microsmeters.

According to still further features in the described preferred embodiments a freezing temperature of the inflatable particulates is below about —20 degrees centigrade, both in an inflated state and in a deflated state of the inflatable particulates.

According to still further features in the described preferred embodiments the

Co inflatable particulates, when in a deflated state, corastitute less than 1 percent of the - free-flowing hydrophobic aggregate by volume.

According to still further features in the described preferred embodiments the . free-flowing hydrophobic aggregate further comprising at least one additive selected from the group consisting of a coloring agent, a UV resistant agent, a bleaching agent and amn abrasive agent.

According to yet an additional aspect of the ppresent invention there is provided a hydrophobic brick comprising a protective encapsulation having a predetermined shapes, and a free-flowing hydrophobic aggregate beding encapsulated in the protective encapesulation.

According to further features in preferred embodiments of the invention described below, the hydrophobic brick further comprising inflatable particulates size wise compatible with capillaries formed between the particulates and capable of absorbing the fluid.

According to still an additional aspect of the present invention there is provicled a method of waterproofing a portion of a structure being in contact with a + groun_d, comprising: providing a bed of a free-flovwving hydrophobic aggregate; and positieoning the structure over or in the bed of the frees-flowing hydrophobic aggregate.

According to further featcares in preferred embodiments of the inventicon described below, the method furthmer comprising protecting the bed of free-flowirag hydrophobic aggregate by enclosing the bed in a protective structure.

According to still further feeatures in the described preferred embodiments a s thickness of the bed of free-flowing hydrophobic aggregate is between 1 and 15 cm.

According to still further features in the described preferred embodiments a thickness of the bed of free-flowing “hydrophobic aggregate is between 4 and 10 cm.

According to a further aspect of the present invention there is provided =a method of waterproofing an undergr-ound wall of a structure, comprising providing at least one sidewall of a free-flowing hydrophobic aggregate adjacent to thes underground wall of the structure.

According to further featur-es in preferred embodiments of the inventior described below, the method furth er comprising protecting the sidewall of free— - flowing hydrophobic aggregate by enclosing the sidewall in a protective structure.

According to still further features in the described preferred embodiments the= method further comprising refillimg the sidewall of free-flowing hydrophobic aggregate, with time.

According to still further featmires in the described preferred embodiments the sidewall of the free-flowing hydropshobic aggregate comprises an arrangement of hydrophobic bricks, each being a protective encapsulation having a predetermined shape and encapsulating the free-flowi_ng hydrophobic aggregate.

According to still further featumres in the described preferred embodiments the method further comprising coating t-he underground wall of the structure with a waterproofing substance selected from the group consisting of a liquid and a paste.

According to still further featuares in the described preferred embodiments the structure is an existing structure, and th_e method is applied as a repair method.

According to still further features in the described preferred embodiments the structure is a new structure, and the me€hod is applied during construction.

According to yet a further aspe=ct of the present invention there is provided a method of waterproofing a floor of a structure, comprising providing a bed of a free- flowing hydrophobic aggregate onto the structure and positioning the floor of the structure over the bed of the free-flowing hydrophobic aggregate.

According to further features in preferred embodiments of the invention : * described beloww, the method further comprising protecting the bed of the free-flowing hydrophobic agzgregate by enclosing the bed in a protective structure.

According to still further features in the described preferred embodiments the s method furthex comprising embedding a pipe in the becd of the free-flowing hydrophobic ag=gregate.

According to still a further aspect of the present invention there is provided a method of waterproofing a roof of a structure, the roof having sidewalls, the method - comprising: applying a bed of a free-flowing hydrophobic aggregate on the roof; and covering the bed of the free-flowing hydrophobic aggregate, to gprotect the bed.

According to still further features in the described prefered embodiments the covering comprises applying a floor over the bed of the free-flowing hydrophobic . aggregate. . Accordirg to still further features in the described prefered embodiments the bed of the free-flowing hydrophobic aggregate comprises an arrangement of hydrophobic bricks, each being a protective encapsulation having a predetermined shape and encap sulating the free-flowing hydrophobic aggregate.

Accordimmg to still further features in the described preferred embodiments a thickness of the bed of the free-flowing hydrophobic aggregate is between 1 and 15 cm.

Accordin_g to still further features in the described preferred embodiments a thickness of the bed of the free-flowing hydrophobic aggregate is between 4 and 7 cm.

Accordingg to still a further aspect of the present invention there is provided a ’ method of waterproofing a reservoir, the method comprising: pla<cing a flooring bed of a free-flowing hy=drophobic aggregate over a base of the reservoir; and placing walls of the free-flowing “hydrophobic aggregate over walls of the resersoir; wherein at least © one of the floaririg bed and the walls of the free-flowing hydrophobic aggregate are . covered by a preotective structure designed and constructed to maintain the free- flowing hydropho~bic aggregate in place.

According: to still further features in the described prefesrred embodiments a thickness of the fl_ooring bed of free-flowing hydrophobic aggregate is between 4 and 15 cm.

Aaccording to still further features in the described preferre>d embodiments the method further comprising mixing the free-flowing hydropholbic aggregate with lightweigzht aggregates.

An ccording to still further features in the described preferreed embodiments the protectiv-e structure is selected from the group consisting of tiless, geotechnic fabric, concrete... plastic and combination thereof.

Aa ccording to still further features in the described prefermred embodiments at least ones of the flooring bed and the sidewalls of the free-flsowing hydrophobic aggregates comprises an arrangement of hydrophobic bricks, each being a protective encapsulation having a predetermined shape and encapsulatinag the free-flowing hydrophobic aggregate.

Amccording to still further features in the described preferred embodiments the free-flowing hydrophobic aggregate further comprises inflatable p=articulates size wise compatit>le with capillaries formed between the particulates and c-apable of absorbing the fluid. oo Au ccording to still a further aspect of the present invention_ there is provided a - ~ method Of protecting an object buried underground, the method comprising providing a free-flowing hydrophobic aggregate and surrounding the objec=t by a layer of the free-flowing hydrophobic aggregate in a manner such that the layer of the free-flowing hydrophobic aggregate is interposed between the object and the grosund.

A_ccording to still further features in the described preferre=d embodiments the size distribution is selected so that a maximal diameter of capillarzies formed between ; the particulates is suitable for repelling the liquid.

A_ccording to still further features in the described preferresd embodiments the size distribution is selected so that the free-flowing hydroplobic aggregate is characterzized by predetermined acoustical isolation ability. : Axccording to still further features in the described preferre=d embodiments the free-flowing hydrophobic aggregate comprises a particulated core r=naterial coated by a + - hydrophobic powder, the hydrophobic powder comprises at least ne impure element having a Bhydrocarbon chain attached thereto.

N Acccording to still further features in the described preferre-d embodiments the hydrophobic powder comprises inflatable particulates capable of abwsorbing fluid when being in czontact therewith.

Accordimng to still further features in the described preferred embodiments the free-flowing hy=drophobic aggregate further comprises at lezast one additive selected } from the group consisting of a coloring agent, a UV resistant agent, a bleaching agent and an abrasive agent. ©5 Accordimg to still a further aspect of the present inv ention there is provided a . hydrophobic ceomposition for protecting an undergrourmd object, comprising a thermally conductive free-flowing hydrophobic aggregate an_d a dielectric free-flowing hydrophobic aggregate, the thermally conductive free-flowimng hydrophobic aggregate and the dielectrac free-flowing hydrophobic aggregate being mixed in a predetermined ratio selected so as to electrically isolate the undergrournd object while allowing transportation o f heat therefrom.

Accordimg to still further features in the described p referred embodiments the hydrophobic c:omposition further comprising inflatable particulates size wise compatible witka capillaries formed between particulates of the thermally conductive .. 15 free-flowing hy~drophobic aggregate and/or the dielectric sfree-flowing hydrophobic aggregate, the iraflatable particulates being capable of absorbing fluid. , Accordimg to still further features in the described preferred embodiments a freezing temper=ature of the inflatable particulates below abowat —20 degrees centigrade, © both in an inflat-ed state and in a deflated state of the inflatabl e particulates.

Accordirg to still further features in the described pareferred embodiments the hydrophobic composition further comprising at least one aedditive selected from the . group consisting of a UV resistant agent, a bleaching agent ard an abrasive agent.

Accordirng to still a further aspect of the present inve=ntion there is provided a method of proteecting an underground object, the method comprising: providing a hydrophobic co-mmposition having a thermally conductive free-flowing hydrophobic aggregate and a_ dielectric free-flowing hydrophobic aggregzate; and surrounding the object by a layer= of the hydrophobic composition in a manner— such that the layer of the hydrophobic co-mposition is interposed between the obje=ct and the ground; the thermally conduactive free-flowing hydrophobic aggregate and the dielectric free- flowing hydroplmobic aggregate being mixed in a predetermirzed ratio selected so as to electrically isolate the underground object while allowing transportation of heat therefrom.

According to still further features in the de=scribed preferred embodiment=s the hyd rophobic composition further comprises imnflatable particulates, size wise conrpatible with capillaries formed between particulates of the thermally conductive free=-flowing hydrophobic aggregate and/or the ddelectric free-flowing hydroplaobic aggregate, the inflatable particulates being capable of absorbing fluid.

According to still further features in the described preferred embodimemnts a free=zing temperature of the inflatable particulates beelow about —20 degrees centigmrade, boti in an inflated state and in a deflated state of thes inflatable particulates. :

According to still further features in the de=scribed preferred embodiments the hydsrophobic composition further comprises at least one additive selected fromm the group consisting of a UV resistant agent, a bleaching agent and an abrasive agent.

According to still a further aspect of the preesent invention there is provid ed a method of manufacturing a hydrophobic composition for protecting an underground obje=ct, the method comprising providing a thmermally conductive free-flovving hydrophobic aggregate; providing a dielectric frese-flowing hydrophobic aggregzate; and mixing the thermally conductive free-flowings hydrophobic aggregate and the dielectric free-flowing hydrophobic aggregate in a predetermined ratio; the pred-etermined ratio being selected so as to allow electrical isolation of the unde=rground object and transportation of heat therefarom.

According to still further features in the des cribed preferred embodiments the unde=rground object is selected from the group consi_sting of an underground electrical : cable=, an underground electrical wire, an undergromund communication cable and” an underground communication wire.

According to still further features in the described preferred embodimentss at least one of the thermally conductive free-flowinge hydrophobic aggregate and the dielectric free-flowing hydrophobic aggregate comperises a particulated core material ~ coatead by a hydrophobic powder.

According to still further features in the described preferred embodiments —the hydros phobic powder has a distinguishable color.

According to still further features in the desceribed preferred embodiments athe particulated core material is further coated by a colori_ng coat.

According to still further features in the desc-ribed preferred embodiments the coloring coat is water resistant.

According to still further features in the described preferred embodiments the ‘method further comprising mixing the thexmally conductive free-flowing hydrophobic : . aggregate and the dielectric free-flowirag hydrophobic aggregate with inflatable _ particulates being size wise compatible with capillaries formed between particulates of 5S the thermally conductive free-flowing hydrophobic aggregate and/or the dielectric free-flowing hydrophobic aggregate, the inflatable particulates being capable of absorbing fluid.

According to still further features in the described preferred embodiments an absorption capability of the inflatable partJculates is from about 100 to about 5000 by weight. ~

According to still further features in the described preferred embodiments a freezing temperature of the inflatable particulates below about —20 degrees centigrade, both in an inflated state and in a deflated state of the inflatable particulates.

According to still further features in the described preferred embodiments a diameter of the inflatable particulates is from about 1 micrometer to about 1000 . micrometers. oT According to still further features im the described preferred embodiments the i. method further comprising mixing the thersmally conductive free-flowing hydrophobic aggregate and the dielectric free-flowing hydrophobic aggregate with at least one additive selected from the group consistings of a UV resistant agent, a bleaching agent and an abrasive agent.

According to still further features im the described preferred embodiments the particulated core material is selected from the group consisting of sand, gravel, slag, porcelanit, dolomite, porcelain, basalt, quartz sand, coal ash, chalk, zeolite, montmorillonite, agapultite, flint, bentonite, perlite, mica, wood chips, nut shells, sawdust and combinations thereof.

According to still further features in the described preferred embodiments at least one of the thermally conductive free-flowing hydrophobic aggregate and the dielectric free-flowing hydrophobic aggresgate comprises a plurality of differently sized particulates.

According to still further features im the described preferred embodiments at least one of a size distribution of the differently sized particulates, a contact angle between a liquid and the differently sized particulates and a characteristic distance between adjacent particulates is selected so that when a layer of the hydrophobi ¢ : composition iss in contact with a liquid having a pressure lower than or equal to a i ) predetermined maximal pressure, percolation of tthe liquid through the hydrophobic 3 composition isz prevented. 5. AccordBing to still further features in the de=scribed preferred embodiments thee liquid is water —

According to still further features in the de=scribed preferred embodiments thee "layer has a thickness from about 1cm to sboumt 10cm and further wherein thes predetermined maximal pressure is equivalent to = column of water having a height above 30 cm.

According to still further features in the de=scribed preferred embodiments thes size distributio=n is characterized by a variance ramnging from 1 micrometer to 1400 micrometer.

According to still further features in the described preferred embodiments the size distributiomn is selected so that a maximal diam_eter of capillaries formed between © the particulatess is suitable for repealing the predetermined maximal pressure of thes - liquid. : 5 According to still further features in the described preferred embodiments the . size distribution is-selected so that a maximal diameter of capillaries formed between 20. the particulates —is from 1 nanometer to 500 nanometers.

Accordimng to still a further aspect of the pre=sent invention there is provided a method of prep=aring an area for plants cultivating, comprising providing a bed of a free-flowing hydrophobic aggregate onto the area and covering the bed of a free~ : flowing hydropliobic aggregate by a layer of soil, theereby preparing an area for plants cultivating,

Accordirmg to still further features in the described preferred embodiments the bed of the free-flowing hydrophobic aggregate comprises an arrangement of hydrophobic pat=ches, each being a protective encapesulation having a predetermined shape and encapssulating the free-flowing hydrophobic aggregate. } 30 Accordin_g to still further features in the desc-ribed preferred embodiments the : protective encapssulation is made from a degradable mmaterial.

Accorcling to still further features in the described preferr-ed embodiments the hydrophobic patches are arranged such that at least one space is formed between adjacent hydrophobic patches.

According to still further features in the described preferreed embodiments the method furthesr comprising covering the bed of the free-flaowing hydrophobic aggregate by a_ super absorbent polymer.

According to still further features in the described preferra=d embodiments the - method furthesr comprising positioning at least one water collection channel for allowing conveyance of water into the soil.

According to still further features in the described preferreed embodiments the method further" comprising surrounding the layer of soil by a protective barrier. : Accord ing to still further features in the described preferre=d embodiments the protective barrier comprises the free-flowing hydrophobic aggregate. ©

Accord-ing to still a further aspect of the present invention there is provided a plant cultivatimg method, comprising: providing a bed of a free-fl owing hydrophobic aggregate an area; covering the bed of a free-flowing hydrophobic aggregate by a layer of soil; plantings a plant in the layer of soil; and applying aqueous 1_iquid under the bed of a free-flowirag hydrophobic aggregate thereby cultivating the plamnt. } According to further features in preferred embodiments of the invention described below, the aqueous liquid is salty water.

Accordi mg to still further features in the described preferreed embodiments the method further- comprising positioning at least one water collesction channel for allowing conveyance of water under the bed of the free-flowing hydrophobic aggregate.

Accordimng to still a further aspect of the present invention sthere is provided a "method of prepzanng a salt-free area on a salty soil, comprising preoviding a bed of a free-flowing hydrophobic aggregate onto the salty soil and covering the bed of the : free-flowing hyedrophobic aggregate by non-salty soil, thereby preparing the salt-free area.

Accordirag to still further features in the described preferred embodiments the further comprising mixing the free-flowing hydrophobic aggregates with lightweight aggregates.

According to still further features in the described preferred embodiments: the methmod further comprising covering the bed of free-flowing hydrophobic aggregat<e by a super absorbent polymer.

According to still further features in the described preferred embodiments the 5s bed of free-flowing hydrophobic aggregate is designed and constructed to facil itate desalination of non-desalted water pres ent thereunder, the desalination being effected by peassage of desalted vapors of the non-desalted water through the bed of the free- flowing hydrophobic aggregate.

According to still further features in the described preferred embodiments the free—flowing hydrophobic aggregate comprises a plurality of differently sized particulates, and further wherein at least one of a size distribution of the particulates, a cont-act angle between a liquid and the particulates and a characteristic distance between adjacent particulates is selected so that when the free-flowing hydrophaobic aggregate is in contact with a liquid having a pressure lower than or equal to a predetermined maximal pressure, percolation of the liquid through the free-flowing hydmrophobic aggregate is prevented.

According to still further features in the described preferred embodiments the metlhod further comprising inflatable particulates size wise compatible with capill aries fornmed between the particulates and capable of absorbing the fluid.

According to still further features in the described preferred embodiments the infl=atable particulates, when in a deflated state, constitute less than 2 percent of the free—flowing hydrophobic aggregate by volume. : According to still further features in the described preferred embodiment s the i inflatable particulates comprise a super absorbent polymer.

According to still further features in the described preferred embodiments the infleatable particulates comprises sodiunn being cross linked with polyacrylic acid. a According to still further features in the described preferred embodiments the infleatable particulates comprises anti-caking agent.

According to still further features in the described preferred embodiments the size distribution is selected so that the free-flowing hydrophobic aggregate is char-acterized by a predetermined specific weight.

According to still further features in the described preferred embodime=nts the size distribution is selected so that the free-flowing hydrophobic aggre=gate is characterized by” a minimal absorption capability.

According to still further features in the described preferred embodimeents the size distributiom is selected so that the free-flowing hydrophobic aggregate is characterized by” predetermined thermal properties.

According to still further features in the described preferred embodimeents the size distributions. is selected so that the free-flowing hydrophobic aggregate is capable of allowing evaporation of liquid.

In any o=f the aforementioned aspects of the present invention, the free- flowing

E hydrophobic aggregate preferably comprises one or more of the hydreophobic *,. composites described hereinabove.

Co The present invention successfully addresses the shortcomings of the presently known configurations by providing hydrophobic composites and particulates, having 15 . properties far exceeding prior art, and suitable for being implemented in various oo applications. Additionally, the present invention successfully addressses the - shortcomings of the presently known manufacturing methods by providing methods of producing the h=ydrophobic composites and particulates.

Unless otherwise defined, all technical and scientific terms used here=in have the same meanirg as commonly understood by one of ordinary skill in the art tao which this invention beslongs. Although methods and materials similar or equivalent sto those described hereim can be used in the practice or testing of the present invention, suitable methods and rmaterials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The invesntion is herein described, by way of example only, with reference to the accompanyirg drawings. With specific reference now to the drawings in etail, it is stressed that the particulars shown are by way of example and for purp-oses of illustrative discumssion of the preferred embodiments of the present invention orly, and are presented in_ the cause of providing what is believed to be the most use=ful and readily understood description of the principles and conceptual aspects of the invemtion. In this regard, no attempt is made to show structural details of the invention "in more detail than is necessary for a fundamental wunderstanding of the invention, “the + description taken with the drawings making apparert to those skilled in the art how the several forms of the invention may be embodied in practice.

In the drawings:

FIG. 1 schematically illustrates a free-flowirng hydrophobic aggregate, havimg a plurality of differently sized particulates, in accordance with a preferred embodiment of time present invention;

FIGs. 2A-B schematically illustrate prior—-art methods of waterproofing a fourmdation of a house;

FIGs. 3A-C schematically illustrate methods of waterproofing a foundatiora of a house, in accordance with a preferred embodimen-t of the present invention;

FIGs. 4A-B schematically illustrate a hydrophobic brick and a hydrophobic brick wall, in accordance with a preferred embodim_ent of the present invention;

FIGs. SA-B schematically illustrate methods of waterproofing a floor oef a "house, in accordance with a preferred embodiment cof the present invention; : | FIGs. 6A-B schematically illustrate prior-artt methods of waterproofing a roof;

FIG. 7 schematically illustrates a method of waterproofing a flat roof, in accoerdance with a preferred embodiment of the pressent invention;

C20 FIG. 8 schematically illustrates a method: of waterproofing a reservoir, in accordance with a preferred embodiment of the pressent invention; :

FIG. 9 schematically illustrates tiles with toothed edges, used for holding hydrophobic aggregate in place, in accordance wikth a preferred embodiment of the preseent invention;

FIG. 10 is a schematic illustration of a hydreophobic composition for protecting an umderground object, according to a preferred emt>odiment of the present invention; , FIG. 11 is a flowchart of a method of gprotecting an underground obj ect according to a preferred embodiment of the present - invention; - FIG. 12a is a schematic illustration of a amn object buried in the ground &and © 30 surrounded by a layer of the hydrophobic composition, according to a preferred embodiment of the present invention;

FIG. 12b is a schematic i Ilustration of an above ground object positionecd in a . dike and surrounded by a layesr of the hydrophobic composition, according to a preferred embodiment of the present invention; and

FIG. 13 is a flowchart of a method of manufacturing a hydrop-hobic s composition for protecting ara underground object, according to a preferred embodiment of the present invenmtion.

DESCRIPTION OF THE PREFEERRED EMBODIMENTS

3 The present invention is Of novel hydrophobic composites and particulate=s that "10 have superior chemical and physsical performances, which can be beneficially ussed in various waterproofing and oil—absorbing applications, and of methods of their production. The present inventi_on is further of the use of free-flowing hydrop=hobic aggregate while providing protesction to the free-flowing aggregates from wined and water erosion. Specifically, the aydrophobic composites, particulates and free-flowing hydrophobic aggregate of the present invention comprise a core and coating compositions which render thee resulting product durable toward a myri=ad of parameters encountered in watemr-proofing and desalination applications such a_s, for example, high water pressures, vwear, reactive detergents and more. The hydrophobic h composites, particulates and free-flowing hydrophobic aggregate of the pmresent : "20 invention are manufacturable faar cost effectively as compared with the prior art hydrophobic composites describe=d in the background section above. : The principles and operat-ion of the hydrophobic composites, particulates, free- * flowing hydrophobic aggregate and the methods utilizing same according teo the present invention may be bettesr understood with reference to the drawings and accompanying descriptions.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention #s not limited in its application to the details of construction and the arrangemesnt of the components set forth in the following : description or illustrated in th.e drawings. The invention is capable of other embodiments or of being practiczed or carried out in various ways. Also, it is -to be understood that the phraseology and terminology employed herein is for the pumrpose . of description and should not be regarded as limiting.

As is discussed in the Background section hereinabove, the presently known hydyophobic composites are limited by both their performance and their effectiveness.

For example, the hydrophobic composites disclosed by Craig, in U.S. Patent No. 4,474,852, were found incapable of withstanding wwvater pressures higher than 2-3 cm s ancl hence cannot be practically used in various common waterproofing applications, such as for example, as a coat of water reservoirs agad as a gravel fill or ballast for road becls or sidewalks, where water-repellency under high pressures is required. The hyeirophobic composites disclosed in WO 03/044 124 include a hydrophobic coating theat is consisted essentially of hydrophobic fummed silica, which is both highly expensive and render the composite’s surface acid=ic and hence susceptible to reactive detergents. Such hydrophobic composites, apart farom being economically inefficient, ana are typically further characterized as environmentally unfriendly, cannot be efficiently used in various applications such as topcoats of various surfaces.

In a search for hydrophobic composites, particulates and free-flowing ag gregate with improved performances, the preserat inventor has found that the use of a ‘Thydrophobic powder of one or more impumre elements having one or more hy-drocarbons attached thereto, optionally in combination with the commercially available hydrophobic fumed silica, can be prepared in an environmental-friendly and eceonomically-efficient process and exert supesrior water-repellency as well as durability toward parameters such as high water pressures, dynamic water wear and reactive detergents.

Hence, according to one aspect of the present invention there is provided a hydrophobic composite which comprises a core material coated by a hydrophobic powder, the powder comprises one or more impure elements having a hydrocarbon cleain attached thereto. As further detailed hereimander, depending on the shape of the coere material, the hydrophobic powder can also be used for providing hydrophobic © particulates and, more preferably, a hydrophobic fi-ee-flowing aggregate.

E As used herein, the phrase “impure elemen_t” includes chemical elements of the periodic table which are not used in their pure Form. The impure elements can be ] 30 naturally impure elements such as, for examples, oxidized elements or carbonated : elements or can be pure or impure elements which have been further impurified by, for ex-ample, small quantities of other elements and/«or various organic substances. The impurity of the element(s) is required so as to render the element susceptible to a surface reaction with an organic substance bearing the hydrocarbon chain, as is further detailed hereinbelow.

The selected elements are preferably metallic, semi-metallic or transition : metallic elements. Representative examples of preferreed elements that are usable in s context of the present invention, in an impure form, include, without limitation, magnesium, calcium, aluminum, zinc, sodium, bar-ium, zirconium, manganese, titanium, vanadium, chromium, iron and combinatioras thereof. The elements are selected according to the desired application of the fimnal hydrophobic product. For example, hydrophobic powder that includes impure calcium, magnesium and/or zinc bearing a hydrocarbon chain is preferable in cases whe=re the final product is used for building and construction applications.

As used herein, the phrase “hydrocarbon chair” describes a chain of carbon atoms that are covalently attached therebetween anc are substituted by hydrogen atoms. The hydrocarbon chain can be linear or brarmched, saturated or unsaturated 1s chain and therefore can be in he form of alkylene chain s that are optionally interrupted or substituted by, for example, one or more aryl groups . The hydrocarbon chain of the present invention includes at least 10 carbon atoms, preferably at least 12 carbon atoms or more, e.g, 13, 14, 15, 16, 17, 18, 19, 20 or nore carbon atoms. Evidently, sucha hydrocarbon chain is highly hydrophobic and thmerefore, when used for coating, 200 renders the powder hydrophobic.

The hydrocarbon chain can be attached to the impure element(s) via various interactions such as electrostatic interactions and Van der Vaals interactions. _ However, the hydrocarbon chain is preferably covalent-ly attached to the element(s), to thereby form a hydrophobic derivative of the element.

Hence, a preferred hydrocarbon chain accordirg to the present invention is a residue of a hydrophobic organic substance that is capable of reacting with the impure element(s). Such an organic substance has a function=al group that can react with the surface of an impure element, the functional group is connected to the hydrocarbon chain.

A representative example of such an organic substance is a fatty acid that has at least 12 carbon atoms. Fatty acids can react with various functional groups that are “present on the impure elements’ surface via its carbox_ylic end, to thereby provide the : hydrophobic derivative described above. Representatdive examples of fatty acids that

WO 2005/005566 PCT/IL2004/0006335 ~ are usable in context of the present invention include, without limitation, stearic acid, . laurjc acid, myristic acid, palmitic acid, oleic acici, linolenic acid and arachidonic acid.

Hence, the hydrophobic powder of the preesent invention preferably includes an impeure element or a mixture of impure elementss, as is defined hereinabove, whereb~y 5s the selected impurity renders the surface of the element(s) susceptible to chemically . reacting with the organic substance described above, which have been reacted with thme orgaanic substance to thereby provide the impur-e element(s) having the hydrocarbo=n resi_due of the organic substance covalently attackned thereto.

A representative example of a hydrophotoic powder that is usable in context Of the present invention therefore includes, without limitations, a powder obtained bey surfiface reaction of oxidized element(s) (e.g., colloidal particles of calcium oxidee, magnesium oxide and the like), which bear free Hydroxyl groups on their surfaces, amd a famtty acid such as, for example, stearic acid. The free hydroxyl groups react with the carboxylic group of the fatty acid, so as to form the corresponding ester.

Another representative example of a hzydrophobic powder that is usable #n © context of the present invention include, witho ut limitations, a powder obtained bey * surface reaction of a carbonated element (e.g., calcium carbonate), which is furthesr - impeurified with oxidized elements such as magnesium oxide and iron oxide, as well eas other substances such as, for example, silicates and sulfates, and a fatty acid as Hs 20° desecribed hereinabove. ‘ It should be noted, however, that a powd_er prepared by reacting the surface Of calcium carbonate, which have been furthem impurified, with stearic acid, ms oo commercially available (for example, from Kfar--Gilaadi Quarries, Israel). However, this powder has never been used as a hydrophobic powder and is presently used only in tie pharmaceutical industry as well as in the pMastic industry.

The hydrophobic powder of the present invention is typically characterized b_y : a surface area ranging between 1 m*/gram and 2¢0 m?/gram. However, in cases where higtaer surface area is required, the hydrophobwic powder can be grinded so as to enhzance the surface area up to more than 50 m?/gzram (e.g., 60 m?/gram). It should b e note=d in this respect that the presently knowwn hydrophobic coatings, e.g., th.e . + hydmrophobic coatings described in U.S. patent NJo. 4,474,852 and in WO 03/0441248, "are characterized by surface areas of abou& 50 m?/gram. While some othesr supethydrophobic powders has a surface area of wip to 250 m?/ gram, it has been showmn herein that a hydrophobic powder having a suarface area of about 60 m?/gram_. is highly efficient due to other physical parameters (e.g., air entrapment, as is. detailed hereinbelow) as well as its low cost.

Due to its particular chemical structure, the hydrophobic powder of tke present invention exerts “soap-like” properties and hence it is further characterized as being inactive toward alkaline reagents, such as det ergents. Once again it should b-e noted in this respect that the presently known hydrophobic coatings that are based on hydrophobic colloidal oxides are characterized as being susceptible to such reagents and hence cannot be used in applications that involve the use of detergents.

The hydrophobic powder of the present invention has an average pamrticles size ranging between 0.02 micron and 50 microns, preferably between 0.1 micron and 20 microns, and more preferably between 0.1 micron and 10 microns.

As is demonstrated in the Exammples section the follows, hserdrophobic composites coated by the hydrophobic powder of the present invesntion are characterized by high water-repellency performance. However, as fs detailed

Do hereinunder, in some cases the use of a combination of the hydrophobic powder of the : .- present invention and hydrophobic fumed sillica can be beneficial.

Thus, according to an embodiment of the present invention, the h=ydrophobic i powder further comprises hydrophobic fumed silica. : 20 As used herein, the phrase “hydropwhobic fumed silica” describes a colloidal form of silica made by combustion of silicon tetrachloride in hydrogzen-oxygen furnaces, in which individual particles on the surface thereof have been chemically bonded to hydrophobic trimethoxysiloxyl groups. Hydrophobic fumed silica is a commercially available powder typically having an average particles size smaller than 1 micron and, if present in the hydrophobic powder of the present invenution, it can constitute between 1 and 99 weight percen-tages of the powder. The resuflting mixed powder typically has an average particle sizee of between 0.02 micron and 240 microns.

Hence, hydrophobic composites according to the present invention may include a core material that is coated by & combination of the hydrophobic powder described hereinabove and hydrophobic fimmed silica, whereas the partial amount of each of these powders is predetermined either by the selected core material and/or by the intended use of the final product. For example, in applications that require high water repellency, the hydrophobic composite or particulates should hzave smaller particles size and hence the mixed powder should consist a higher amount of the hydrophobic fumed silica. In applications that require lower water-repellency, the hydrophobic composite or particulates can have larger particles size and hence the mixed powder consists a higher amount of the hydrophobic powder described hereinabove. The use of a minimal amount of hydrophobic fumed silica is highly advantageous as it substantially reduces the cost of the final product.

In any event, the hydrophobic powder of the present invention, alone or in combination with hydrophobic fumed silica, constitutes between about 0.1 and § weight percentages of the hydrophobic composite, whereby powders that include higher amount of the hydrophobic powder described hereinabove constitute between © about 2 and about 5 weight percentages of the composite and powders that include higher amount of the hydrophobic furmed silica constitute between about 0.1 and about - 2 weight percentages of the composite.

As used herein throughout, the: term “about” refers to + 10 %.

The core material coated by the hydrophobic powder of the present invention may be selected from a wide variety of organic and inorganic substances, with inorganic substances (e.g, minerals) being favored from standpoint of cost and availability.

The physical form of the core unaterial may vary, with particulate and granulate material being preferred. Preferred core materials have an average particles size ranging between about 25 millimeters (25,000 microns) and 5 microns, more preferably between 10 millimeters and 20 microns, more preferably between $ millimeters and 100 microns and most preferably between 1,000 microns and 200 microns. Such a core material is also referred to herein throughout as aggregate. Non- particulated, non-granulated, integral core materials are also within the scope of the present invention.

Representative examples of core materials that are preferably usable in context of the present invention include, without limitation, sand, gravel, slag, porcelanit, dolomite, porcelain, basalt, quartz sand, coal ash, chalk, zeolite, montmorillonite, agapultite, flint, bentonite, perlite, anica, wood chips, nut shells, sawdust and combinations thereof.

A representative example of a preferred core material according to the present oo invention is quartz sand having a particle size of between 600 and 800 microns.

: The hydrophobic composite of the present invention preferably fuscther compr=ises an adherent layer, which boneds the hydrophobic powder to the core material. The adherent layer serves as a firsst coat layer deposited on the core material, whichz anchors the hydrophobic outer coat tiaereto.

The adherent layer preferably comporises a film forming agent such as a film formimng polyurethane. Any of the film-forrming polyurethanes commonly employed in the field of coatings may be used in the practice of the present invention. Included in this c=ategory are the well-known two-cormponent and one-component polyurethane . coatitg systems. The two-component sysstems arc formed by the reaction Of an aliphatic or aromatic isocyanate with a hydroxyl-bearing compound, such as * polyflunctional polyesters based on adipic a cid, phthalic anhydride, ethylene glycol and © trimesthylolpropane, for example. Representative of the one-component polyurethane : : coatirg systems that may be employed as the adherent layer are those derived from stables isocyanate-terminated prepolymers formed from an aliphatic or arommatic 15° isocy=anate and polyfunctional polyether om polyester. These one-component systems are caommonly referred to as "moisture cumred" polyurethane coatings because drying results from the reaction of the free-isocyzanate groups of the pre-polymer with ~water or atmospheric’ moisture. Another one-c-omponent polymer coating which may be used in the preparation of the hydroph-obic composites is the "urethane oil" or “urallikyd", which is the reaction product ofa diisocyanate with a hydroxyl-conteaining dryin_g oil derivative, e.g., that produced by alcoholysis of an unsaturated glyceride with =a polyol, such as trimethylolpropane. .

The adherent layer of the present invention may further comprise a gluing agents in combination with the film-formirmg agent, so as to provide an increase in the anchoring quality of the adherent layer ov—er a longer period of time and an increased © attraction for oil and oil related products. JHence, the presence and the relative armount of th-e gluing agent depend on the need -of such properties, in accordance with the inteneded application of the final product.

The gluing agent preferably comprises a volatile hydrocarbon that has a€ least 12 carbon atoms, such as, for example, asp=halt.

As used herein, the term “asp-halt" describes a dark brown to black cemesntitious material in which the predom_inate constituents are bitumens that occur in natur-e or are obtained in petroleum processing, the latter being preferred, prirmarily because Of its greater availability. The asphalt may be solid, semi-sowlid or liquid, with the latter being preferred.

However, other gluing agents, such as, for example, paraffin wax, beeswax, lanolin w=sx, linseed oil and any other commercially available wax, can be used in this context oef the present invention, though their relative amount in the adherent mixture . is preferambly lower than that of the asphalt.

More preferably, as is detailed hereinbelow, the adherent laye=r is a water-based adherent layer, preferably comprising a water-based gluing agent. "The adherent layer of the present invention preferably co-nstitutes between about 0.25 and about 7 weight percentages of the hydrophobic composite, more preferably between 1 and 5 weight percentages of the hydrophobic composite, dependin_g on the particles size of the core material, the selected process of preparing the hydrophobic composite, particulate or free-flowing aggregate and the intended application of the final product. For example, in cases where the comre material has an average particles size ranging between 150 microns and 1000 m_icrons, a smaller amount Of the adherent layer, e.g., between 0.5 and 1 weight peercentage of the hydropho=bic composite, is used. In cases where the core material hans particles larger than 1000 microns or smaller than 150 microns, a higher amount of the adherent layer "is preferred. As is discussed in detail and is further exemplified in the Examples section timat follows (see, Examples 5 and 9), using a higher amourmt of the adherent layer (e.g=., more than 1 weight percentage of the composite, preferably 2 weight percentages) results in composites enriched with “free particles”, which are characterized by enhanced resistance to dynamic wear. Also, h-igher amount of adherent 1 ayer (e.g., between 3 and 7 weight percentages of the compwosite) is required in cases ~where the hydrophobic composite is prepared in a “cold” process, as is detailed heereinbelow.

Ass is further described and exemplified in the Examples sec=tion that follows (see, Exannple 10), the required amount of the adherent layer may be roredetermined.

The adherent layer of the present invention is easily applied to the core. © 30 materials Wby dissolving the film-forming agent and the gluing agents, if present, in a volatile solvent, so as to form a homogeneous composition and to prrovide a uniform deposition. of the adherent layer over the surfaces of the core mmaterials. As is

WeaQ 2005/005566 PCT/TL2004 #000635 desscribed in detail hereinbelow, such an adherent layer mixture is mixed with the core material while the volatile solvent is evaporated. . Preferred compositions of the adkerent layer mixture include a film-feorming p olyurethane in an amount ranging bet-ween 5 and 25 weight percentages of the adherent layer mixture, depending on thes size and type of the core material; a gluing agent in an amount ranging between 0 anad 25 weight percentages of the adheremnt layer mixture, depending on the core material used, the gluing agent used and the imtended tase of the final product; and a volatile sclvent in an amount of between 50 and 95 wveight percentages of the mixture, depending on the amounts of the other components.

As the volatile solvent merely functions as a vehicle for depositing the adherent layer on the core materials, virtually any volatile solvent in which the components of the adherent layer are soluble may be used. However, p-referred ssolvents include petroleum distillates, stich as mineral spirits or paint thinnesr, which

Pave a boiling temperature of betwe=en about 80 °C and about 200 =C. A wrepresentative example of a preferred volatile solvent is toluene, which is readily «evaporated at relatively low temperatur<es and results in rapid spread of the mixture -onto the core materials.

So Optionally and preferably, a water-based adherent layer is easily applied to the core materials by dissolving a water—based gluing agent in an aqueous solvent, preferably water, so as to form a homogzeneous composition and to provide a uniform deposition of the adherent layer over the surfaces of the core materials_ As is described in detail hereinbelow, such an_ aqueous adherent layer mixture is mixed with the core material and is thereafter tumble dried so as to remove the aqueous so-1vent.

The hydrophobic composites of the present invention can further ecomprise . 25 various additives which, in accordances with the intended application and the core . material used, provide hydrophobic composites with improved characteristics.

Representative examples of such additives include, without limitations, coloring agents, UV resistant agents, bleaching a gents and abrasive agents. :

Coloring agents that are usable Jn context of the present invention include any of the presently known mineral or or-ganic coloring agents, with mineral coloring agents being preferred. A preferred amount of the coloring agent adde=d to the composite ranges between about 0.1 and 2 weight percentages of the hydrophobic composite.

The resulting colored hydrophobic composites may be benefi cially used in various applications, such as applications that require easy identification of the hydrophobic composite or applications that involve external coating. A_ representative example of such an application is the use of colored hydrophobic sand to mark s submerged «cables, so as to warn against excavation nearby. The addition ofa coloring agent to thes hydrophobic composite is further beneficial as it can some=times improve the surface tension of the composite, thus rendering it more hydrophobic.

UV resistant agents are added to the hydrophobic compositess of the present invention im order to improve the durability of the composites against UV irradiation, and are hence particularly useful in high radiation geographical site=s, e.g., for top- coats of ro-ofs or other surfaces. Representative examples of UV resistant agents that : are usable in context of the present invention include, without limitation, titanium dioxide an~d zinc oxide, both may also serve as bleaching agents. A p-referred amount of the UV” resistant agent and the beaching agent added to the composite ranges between about 0.01 and 2 weight percentages of the hydrophobic composite.

Abmrasive agents are typically added to the hydrophobic compe osite in order to improve tthe wear resistance of the composites and are therefore typically used in applicatiomns where the composites are exposed to continuous wear. Representative examples of abrasive agents that are usable in context of the present irvention include, without limitation, powdered abrasives such as titanium dioxide and =aluminium oxide a (A1,03, corundum). A preferred amount of the abrasive agent added to the composite ranges between about 0.1 and 0.25 weight percentages of the hydropheobic composite.

The hydrophobic composites of the present invention are the-refore comprised of a core material, as is described hereinabove, which is coated by the hydrophobic powder described hereinabove, preferably in combination with hyedrophobic fumed silica, aned preferably further include an adherent layer, as is descri_bed hereinabove.

Optionall_y, the hydrophobic composites of the present invention further comprise additives for improving their properties in accordance with their intermded application.

A_ representative example of a hydrophobic composite accordling to the present inventiom is quartz sand coated by a mixture of the hydrophobic powder described herein ard hydrophobic fumed silica, in a ratio that ranges between 20:1 and 2:1, whereby this hydrophobic mixture is bonded to the sand via an adher-ent layer.

The hydrophobic compositzes of the present invention are supe rior to the presently known composites as thes include inexpensive and available maerials, they are characterized as inactive toward alkaline reagents such as detergents, and, as is demonstrated in the Examples secction that follows, they exert supemrior water- 5s repellency and are further characterized as being capable of prevemmting water adherence thereto and water penetramtion therein under an external pressure ef at least 2 atmospheres and up to almost 5 smtmospheres, and as being highly duramble toward dynamic water wear, namely, as reemaining hydrophobic under continuotas dynamic water wear for at least two months.

The hydrophobic composites of the present invention can therefore be utilized in a myriad of applications, such as, but not limited to, as waterproofing agents in - building and pavement construction. as fill or bed materials under concrete slabs or as wall coatings, both below and abov-e ground, as gravel fill or ballast for road beds or . sidewalks, as top coats on paved surfaces, in top hole repairs in ro=adways, as substitutes for common aggregatess in asphalt roofing or shingles, or Jin built-up roofing. In addition, these hydrophobic composites may be applied to painteed surfaces to provide a durable, waterproof firish over wood, metal, concrete, stone, brick, and certain synthetic substrates.

Further according to the pr-esent invention, there is provided a method of preparing the hydrophobic composites described above. In general, the method is effected by coating a core material, zas is described hereinabove, with the hydrophobic powder of the present invention, opationally in combination with hydrophowbic fumed : silica. The amount of the hydrogphobic powder and the relative amount of the hydrophobic fumed silica are predetermined as is discussed hereinabove. In cases where a mixture of the hydrophob ic powder and the hydrophobic fumed silica is . _ applied, the mixture is prepared is = separate vessel prior to applying ther-eof to the . core material.

In cases where the compositee further comprises an adherent layer ®&hat bonds "the hydrophobic powder to the core material, the method further comprises, prior to

C30 coating with the hydrophobic powwder, applying onto the core material such an adherent layer, and, more specifically, admixing a pre-prepared adherent layeer mixture : that contains a film forming agent, a volatile solvent and optionally a gluinge agent, as is described hereinabove, with the core material, while removing all of thee volatile solvent from the resulting mixtwure, so as to provide a core material having the asdherent layer applied thereon.

Optionally and preferably, the adherent layer is a water-based adherert layer and the method further comprises, prior to coating with the hydrophobic powder, applying onto the core matemial such an adherent layer, and, more specifically, admixing a pre-prepared adherent layer mixture that contains a water-based gluing agent and an aqueous solvent, as is described hereinabove, with the core material, while removing all of the aqueous solvent from the resulting mixture, so as to gprovide a core material having the water-based adherent layer applied thereon.

As is described in detamil in the Examples section that follows, the adherent layer mixture is prepared by mi_xing its components under heat and is preferable, added to the core material while hot. The relative amount of each component in the rmixture is predetermined as is discusse=d hereinabove, while the total amount of the re=quired adherent layer can be also predetermined, as is described and exemplified in the

Examples section that follows,

The removal of the volatile solvent is typically performed by evaporative heating, but can alternatively bes performed at room temperature. ) Hence, the entire processs can be performed under heat or alternatively can be performed as a “cold” process, whereas no external heat is applied, as is exemplified © 20 in the Examples section that follows. The “cold” process typically involves higher amount of the adherent layer.

In any event, as the ceore material should contain no more than 1 —weight percentage moisture, so as to ensure uniform coatings of the particles, th-e core material is preferably dried to this extent prior to the coating procedure. Thee core material is typically dried at =a temperature ranging between 90 °C and 1220 °C, preferably at about 104 °C. Upon being dried, the core material can be used hot or can be stored in a closed vessel and be thereafter coated while cold.

Once the hydrophobic cosmposite has been prepared, it is preferably cured so as to obtain the final product. Thes curing time typically ranges between 1 and 30» days, depending on the composition of the hydrophobic powder. For example, in cases where only the hydrophobic powder of the present invention is used, a curing time of 30 days is required. In cases w~here the hydrophobic powder is in combinatior with hydrophobic fumed silica, the curing time is shortened proportionally to the relativee amount of the hydrophobic fumed silica, and down to 1 day.

The use of water-based reagents or mixtures in preparing hydrophobic composites, as well as in other applications, has recently become highly intriguingz, = particularly in view of new environmental wegulations and other limitations associatecl with organic reagents, solutions or mixtures.

While processes performed in «organic solvents are considered highly disadvantageous in terms of cost, simplicity, safety, hazardousness and environmenteal considerations, process performed in aqueous solutions in general, and in water im 1 0 particular, are completely devoid of these disadvantages.

Thus, preparation of hydrophobic composites, which involves that use of water-based adherent layer and thus uses aqueous solutions as the main preparatiosn medium, is highly beneficial as it is cost-effective, safe, uses a simplified system amd is environmentally friendly.

ES However, the use of water-based reagents or mixtures for binding a hydrophobic material, which is aimed at repelling water, as in the case of the compositions of the present invention, is highly intrinsic.

The present inventors have surpriisingly found that hydrophobic compositees which include a core material and a hydrophobic material bonded thereto via a wate=r- based adherent layer can be easily prepared, while still achieving the desired characteristics of the resulting hydrophob&c composites. As is discussed hereinabov—e, : such hydrophobic composites are highly advantageous since they involve the use of= a " cost-effective, easy to handle, safe and enwironmentally friendly aqueous medium.

Hence, according to another aspect of the present invention there is provided a =25 hydrophobic composite comprising a cores material coated by a hydrophobic materizal, whereby the hydrophobic material is borded to the core material via a water-baseed adherent layer. - In order to provide a water-based adherent layer which will effectively bind a hydrophobic material to a core material, two requirements should be met: (i) the ccore material having applied tehreof a water-based adherent layer must be effectively dried, so as to provide a substantially w ater-free adherent layer, prior to its coati-ng with the hydrophobic material; and (ii) the adherent layer should retain its tackine=ss

(its gluing property) in its substantially dried fosrm, so as to allow efficient binding of the hydrophobic material thereto.

In addition, since the hydrophobicity of the resulting composites depeneds on the contact angle, as described hereinbelow, and further since the contact angle s depends on the physical entrapment of air withilin the composites, it is highly desirable to select an adherent layer which enables the formation of a physical structure eof the hydrophobic layer that entraps as much air as physically possible.

An appropriate and efficient water-bas-ed adherent layer is therefore se lected so as to meet the above requirements, as we=ll as ease of use, cost, other physical requirements and its interaction with the selected hydrophobic coating material.

A water-based adherent layer, accordimmg to the present invention, can bee used in any hydrophobic composite, regardless of the core material and the hydrophobic material. Nevertheless, appropriate and efficient hydrophobic coating materiaals are selected in accordance with the required phy~sical properties of the final cormposite (e.g., shape), as is detailed herein, as well as in accordance with its interaction with the selected water-based adherent layer.

The water-based adherent layer accorcling to the present invention preferably comprises a water-based gluing agent, which can be selected from a wide variety of commercially available water-based gluing agents.

Representative examples of commercially available water-based gluing= agents include, without limitation, Bitumen-Latex and Bitumen-Polymer binders ssuch as ' Bitumflex (by Bitum, Israel), Elastopaz and E-lastobrush (by Pazkar, Israel), Speecef 10 and Specef 52 (by Wacker, Germany), Dispercoll c, Dispercoll u, Dispercolll s and

Desmodur d (by Bayer, Germany), Enimoert, Hiniplast and Hidropren 40-20 (by

Enecol, Spain) and many more.

While these gluing agents are widely recognized in the art, they haves never - been practiced before as an adherent layer th_at binds hydrophobic material to- a core material, particularly a particulated core mateerial, to thereby produce a hydrcophobic composite.

The water-based bitumen binders a=zre collectively referred to here-in as a bitumen-latex paste. The water-based gluing -agent, according to the present in—vention, preferably include one or more water-based gluing agent(s), optionally and preeferably selected from the commercially available wateer-based gluing agents listed abowe.

The water-based adherent layer is easily applied onto a core material by simply dissolving it in water, or in any other aqueous medium, and applying the resulting mixture onto the core material. The resulting core material should thereafter be substantially dried, as is described hereinabove. The drying is preferably performed by heating the core material as described herein, optionally and preferably, in combination with a blower or any other technique that may accelerate and enhance the drying process at this stage.

The core material used can be any core material, and is preferably a core material as described hereinabove.

The hydrophobic material can be, for example, the hydrophobic powder described hereinabove, alone or in combination with hydrophobic fumed silica, hydrophobic fumed silica per se ©r any other silicon-based hydrophobic powder, molten polypropylene and other hydrophobic polymers, as well as any other hydrophobic material or supethydrophobic powder usable in hydrophobic composites, ~ and any combination of the forgoing.

Following are descriptions of applications for which the hydrophobic composite and particulates described above can be employed, according to preferred embodiments of the present invention.

Hence, as stated, the hydrophobic composite of the present invention can be used for manufacturing a free-flowing hydrophobic aggregate, referred to herein as aggregate 1, having enhanced waterproofing properties. Aggregate 1 is capable of repealing a predetermined maximal pressure of liquid. As further detailed hereinunder, by judiciously selecting several parameters of aggregate 1, a layer of the aggregate of relatively small thickness (of the order of centimeters) is sufficient to withstand a column of water or any other liquid of interest. According to a preferred embodiment of the present invention, the column is above 30 cm in height, more - preferably above 100 cm in height, most preferably above 10m in height. A typical

B thickness of the layer is from about 1 cm to about 20 cm. nn The ability of any hydrophobic material to repeal water basically depends on the surface tension of the liquid being in contact with the hydrophobic material. In any liquid, the cohesive forces between molecules present deep in the liquid are shared : with all neighboring atoms. The surface molecules of the liquid have no neighboring atoms of the same type above and exhibit stronger cohesive forces upon the molecules y directly associated with them on the surfacce. From a macroscopic point of view, the enhanced intermolecular interaction at thee surface of the liquid is obserwed as the surface tension of the liquid. : E The cohesive forces between likes molecules compete with external forces existing between the molecules of the liquid and molecules of the material contacting : the liquid. When this material is hydreophobic, the cohesive forces si gnificantly dominate, the free surface of the liquid becomes film-like and the liquid is irmcapable of wetting the hydrophobic material.

Referring now to the drawings, Figure 1 is a schematic illustration off aggregate 1, which preferably comprises a plur ality of differently sized particulates 2 - characterized by several (specifically selected) parameters which influence the level of the external forces and thereby the hydrosphobic properties of the aggregeate. These : parameters includes, but are not limited to, a size distribution, M, of particulates 2, a contact angle, 6, defined between the liquid and particulates 2 and a characteristic distance, r, defined between adjacent particulates.

M, © and r are preferably selected depending on the waterproofing application for which the aggregate is designed to be- used, and in accordance with thwe maximal liquid pressure expected in the specific application. More specifically, M and the

RB 3 cosine of © are preferably proportional to the pressure and r is preferabls inversely h 20 proportional to the pressure. Mathematically, the relation between thes maximal pressure, P, and the above parameters may be expressed using the followings empirical formula:

P= kM cosb/r, (EQ. 1) where k is a constant of the proportional ity and the angle, 6, is measure«d from the tangent to a surface defined by the layer off the free-flowing aggregate. One ordinarily skilled in the art would appreciate that only when the right-hand-side of Eqguation 1 is i positive, the aggregate is wetted by the liqwaid which may then percolate there through. : Thus, according to a preferred embodimerat of the present invention, cosd -is negative so that the aggregate remains dry at all tinnes. This can be achieved by sel ecting 6 to be from 90° to 180°, where larger values of 6 within this range corresponed to larger . pressure under which the aggregate remains dry and vise versa.

The contact angle, 8, depends on the materials from which the hydrophobic aggresgate of the present invention is made. A detailed description of materials which were found to be suitable to various waterproofing applications is provided hereinafter.

A non-uniform size distribution allows for beetter control on the capillary size of aggregate 1. Capillary size is a measure of time diameter of capillaries formed * betweeen the particulates of the aggregate.

Thus, according to a preferred embodiment of the present invention the size distri bution, M, is selected so that a maximal diameter of the capillaries is suitable for repelling the liquid at the pressure, P. One orAinarily skilled in the art would appreciate that the more M is non-uniform the smaller the size of the capillaries. A typical diameter of the capillaries is from 1 nanometer to 500 panometers. Such diameeter is size wise compatible with capillaries formed in concrete matrices.

Generally, the size of the particulates may v-ary between about 25 millimeters (25,0 O0 microns) and 5 microns, more preferably between 10 millimeters and 20 microns, more preferably between S millimeters and 100 microns and most preferably . betwe=en 1,000 microns and 200 microns. . g In a construction site, large size particulaftes are easier to handle. Thus, . deperading on the application and the desired diameter of the capillary the manufacture can select the characteristic variance of the size distri “bution of the aggregate. ) More specifically, in applications in which thee expected column of liquid is not high eof the order of a few centimeters) it is sufficient to provide larger particulates "and s=mall variance, whereas if the expected column of liquid is higher (of the order a few nmeters) the particulates are preferably smaller ir size and larger in variance. For exampple, for a column of liquid of about 50-100 cm =the preferred variance is about 50 microsmeters, for a column of liquid of about 1-10 m - the preferred variance is about 30 micrometers and for a column of liquid of about 1e0-50 m the preferred variance is about 10 micrometers. It is to be understood that the above variances are representative examples and should not be considered as limiting.

Other physical quantities which can be affescted by M include, but are not limite~d to, the specific weight of the aggregate, wat=er absorption capability, thermal propencties (e.g., thermal conductivity, specific heat ca-pacity, latent heat) and acoustical isolati_on. Thus, by varying the size distribution, M, =an application-oriented aggregate

MNO 2005/005566 PCT/IL200=8/000635 may be formed. For example, in an acoustical isolated waterproofing applicatiosn M is selected so as to maximize the acoustical iseolation of the aggregate, in temperature isolated waterproofing application M is seslected so as to minimize the tThermal conductivity of the aggregate, etc.

A judicious selection of the size distribution can also be used to control the ability of the aggregate to allow evaporation of the liquid there through. Evap oration "Of the liquid through the aggregate enhances the ability of the aggregate to maintain the environment dry and allows vapor passsage and equilibrium of vapor pressure. “This is in contrast to fully sealed waterproofing materials where the water is =trapped inside the volume defined by the matermal. Hence, according to & preferred "embodiment of the present invention, M is selected so that the aggregate is capable of allowing evaporation of the liquid.

One of ordinarily skill in the art would appreciate that the above parameters which, as stated, are selected in accordance wvith the pressure to which the aggaregate 1 iis expected to be exposed, are static. In Other words, the set of parameters, once selected, fix the pressure limits in whicka aggregate 1 can be effectively used.

Slowever, on some occasions, the pressure actually applying on aggregate 1 on site exceeds the expected limits, e.g., under extareme and unexpected weather comditions.

Jn addition, being made of many particulemtes, aggregate 1 may exhibits statistical fluctuations in which locally the capillaries exceed their average size by several standard deviations. Furthermore, in infkerfaces between hydrophobic and non

Thydrophobic layers, a relatively large capillary size is typically formed. The goroblem -of large interface capillaries is non statistical and affects the overall pressure under which aggregate 1 can be used. This probl em may be solved by applying acihesives “between hydrophobic and non hydrophobic 1 ayers, as further detailed herein urmder.

While reducing the present inventionm to practice it has been uncovered that the capillary size of aggregate 1 may be significeantly reduced using inflatable particulates capable of absorbing fluid (e.g., water). Cdnce being in contact with the ligguid, the inflatable particulates dynamically adjust to the liquid pressure, even winen this pressure exceeds its expected value,

Due to the judicious selection of the static parameters of aggregate 1 Ce.g., the size distribution, M), the inflatable particula_tes inflate only when the pressures excides the expected pressure to which aggregate 1 is designed. As the pressure rise, the

_ inflatable particulates start to inflate thus establishing a dy-namic pressure barrier. It - will be appreciated that most waterproofing applications =are performed in a closed : spaces, so that the inflation of the inflatable particulates increases internal forces within aggregate 1, blocking residual capillaries and thus enhancing the ability of aggregate 1 to prevent percolation of liquid and passage of wvater vapor.

The inflatable particulates may be incorporated into aggregate 1 in more than one way. Hence, in one embodiment, the inflatable particu=lates may be integrated in, or attached to particulates 2, already in the manufacturing stage thereof. This embodiment is further detailed hereinafter, following the -description of the suitable materials which may be used to manufacture aggregate 1.

In another embodiment, the inflatable particulates are in the form of free "particulates (e.g., a powder). Referring now again to Figures 1, an inflatable particulate 3 is present in void 4 between particulates 2. When a local increase of liquid occurs, . particulates 2 are pressed one against its neighbors, while, xt the same time, inflatable particulate 3 absorb the liquid and begins to inflate, heence operates as a small . "balloon" having a dynamically expanding surface arca. MExternal forces, caused by particulates 2 and acting inwards to void 4 limit the inflating= process so that particulate 3 becomes a three-dimensional structure whose shape is similar to the shape of void 4. ' The inflating process is terminated when particulate 3 essentially occupies void 4, thus reducing the characteristic distance, », and increasing the pressure, P, under which aggregate 1 is effective. When several such inflatable parti culates are present in void 4, the filling of void 4 is more efficient.

According to a preferred embodiment of the present Invention, the average size of inflatable particulates is selected so that, when the inflatable particulates are in deflated state, at least one inflatable particulate or, more preferably, several inflatable . particulates, occupy void 4. In this embodiment, a typi cal size of the inflatable ~ particulates is from about 1 micrometer to about 1000 micrometers, preferably, 5-500 . micrometers.

Although more than one inflatable particulate may Occupy the same void, the inflatable particulates preferably are devoid of any flumid communication there ~~. . amongst, so that even when the inflatable particulates are Sin inflated state, the free- flowing nature of aggregate 1 is maintained. This may be accomplished, for example, oo if the inflatable particulates constitute a sufficiently smamll volume percentage of aggregate 1. Preferably, the Anflatable particulates constitute les-s than 1% of aggregate 1 by volume, more preferably about 0.2 %.

The voids between the hy~drophobic surfaces of particulates 2 form a network, at least partially interconnected, in which the largest voids deterrmine the entire s behavior of aggregate 1. Thus, the incorporation of even a low= percentage of inflatable particulates, results in aa small residual number of large intereconnected voids hence significantly improves the “resistance of aggregate 1 to pressure.

According to a preferred embodiment of the present inventi=on the swelling time of the inflatable particulates is sufficiently small (preferably unde-x 10 seconds) so that aggregate 1 quickly resposnses to any contact with water. The absorption capability of the inflatable particulates is preferably from about 100 to about 5000 by weight, more preferably from about 200 to about 2000. by weight . The freezing temperature of the inflatable particulates is preferably below about —20 °C (both in - inflated and in deflated states) sso that aggregate 1 maintains its free-flowing nature even at low temperatures. A _judicious selection of the material —from which the

BN inflatable particulates are made= may result in that cycles of absorgption-desorption - thereof can be is repeated endlessly. . Any material known capable of swelling when in contact withm a liquid can be used for the inflatable particulates, provided that the combination of the inflatable particulates and particulates 2 maintains the free-flowing nature eof aggregate 1.

Representative examples for suck materials include, but are not limited to, starch, clay, bentonite, water blockers of various types and the like. Additional c=haracteristics of interest for the inflatable particulates include, without limiting, th ermal isolation, liquid absorbency, sufficiently low freezing temperature, deflatings ability in dry environment and the like. . According to a preferred. embodiment of the present inventio-n, the inflatable particulates are made of a supest absorbent polymer (SAP), also kn-own as Polyols polymers.” SAPs are known im the art for many years. What meakes SAP water absorbent is the presence of a chemical such as sodium or potassiunm molecules that cross-links between the hydrocarbon chains of a polymer. These cross-links allow the polymer to form into a single sumper-molecule capable of holding sigraificant amounts : of water. The polymer is typical ly polyurethane, urethane or polypropylene, but other polymers may also be used. T here are hundreds types of SAPs, characterized by st varicous parameters, such as their water pick-up capabilities. the temperature at which water is absorbed and desorbed, abruptness of water release sand the like.

A representative example of a SAP include, without= limitations, sodium cross linkeed with polyacrylic acid. Similar SAPs include, but are not limited to,

LiquaiBlock™ 80, LiquiBlock™ 88, LiquiBlock™ At-03§, LiquiBlock™ 80HS,

LiquaiBlock™ 88Hs, LiquiBlock™ 144, LiquiBlock™ 14=4TRS, Norsocryl™ 8-35,

Norssocryl™ D-60, Norsocryl™ XFS, all of which are pu-rchasable from Emerging - Technologies, Inc., North Carolina, USA. These SAPs were experimentally found to be suitable for incorporating with the aggregate 1. Other SAPs are presently manufactured by, and are available from, Union Carbide , BASF Corporation and man—y other companies.

According to a preferred embodiment of the preserat invention the inflatable parti_culates may comprise an anti-caking agent to minimize liquid communication between adjacent inflatable particulates. For example, Norsocryl™ XFS and

LiqumiBlock™ 144TRS, above, include an anti-caking agent. :

Normally, without hydrophobic aggregates, large ameount of SAP is needed for wate=rproofing or blocking the passage of water. This makess the use of SAP, difficult and eexpensive. One of the advantages of this embodiment of the present invention is that sthe SAP is used only for the purpose of bridging betwesen capillaries, while most of the waterproofing is accomplished by the inherent hydrophobic properties of » aggregate 1. Thus, only a small amount of SAP is neeeded, as further detailed - herei-nabove.

In experiments made by the inventor of the present in—vention, it has been found ..- that "by adding an amount as small as 0.2% of Norsocrsyl S-35 with an average particulate size of 100-500 micrometers, absorption capabillity of more than 500 by weighht and swelling gelling time of about 6 seconds, ssignificantly reduced the capillary size of aggregate 1. In particular, it has been found that the above-mentioned probl em of the large capillaries between hydrophobic and nor-hydrophobic layers was almosst completely eliminated. The elimination or at least recluction of this problem is particoularly useful in waterproofing applications in which object (e.g., pipes, tanks, etc.) lies within a hydrophobic layer. In such cases, there is a large surface contact between hydrophobic and non-hydrophobic layers.

It is amticipated that many types of inflatable particulates will be developed during the lifes time of this patent, and it is therefore within the scope of the present invention to irclude all such inflatable particulates a-pr—iory.

Accorcling to a preferred embodiment of the praesent invention the hydrophobic s aggregate mexy be mixed with hydrophobic coatesd lightweight aggregates, for example, Pummis, Perlite, volcanic aggregate, crastmed foam concrete, etc. The lightweight aggregates serve for reducing the overall weight of the mixture. The reduced weighht is important, for example, when the mmixture is used for waterproofing roofs, flooring or any waterproofing done indoors.

For puarposes of better understanding the use of the free-flowing hydrophobic aggregate in waterproofing applications in accordance with preferred embodiments of . the present inmvention, reference is first made to a con~ventional (i.e., prior art) method of waterproofing as illustrated in Figures 2A-B.

Refermring now to the drawings, Figures 2A-B schematically illustrate prior-art methods of waterproofing a foundation of a structure 710 on a ground 12. In general, a foundation lemyer of pebbles 22, and sidewalls of pe=bbles 20 are provided as water channels to amllow for water flow adjacent to underground section 14 of structure 10.

Additionally, the foundation walls of underground section 14 may be covered with tar or a similar naterial, as an additional water protection . However, when the water table ishigh(eg., on rainy days or when a plumbing probleem occurs), side pressure 16 and - upward pres=sure 18 may nonetheless be applied to the foundation walls by the a. underground water, causing cracks and possibly penet-rating underground section 14. ) Accomrding to another aspect of the present= invention there is provided a method of waterproofing a portion of a structure beimg in contact with a ground. The method comporises the following method steps in whi ch in a first step a bed of a free- flowing hydmrophobic aggregate is provided, and im a second step the structure is positioned ower or in the bed. According to a preferred embodiment of the present invention an_y free-flowing hydrophobic aggregate may be used, such as, but not limited to, aggregate 1 mentioned hereinabove or anotther commercially available free- flowing hyd-rophobic aggregate (also known in thie literature as "magic sand"), manufactured, for example, by Clifford W. Estes Co. Inc., New Jersey, USA, and

Educational Innovations, Connecticut, USA. Yet, sadditional aggregates useable in context of thae present invention are described in U.S. Provisional Patent Application

Nos. 60/486,419 and 60/486,420, WO 03/044124- and U.S. Patent No. 4,474,852, all of © which are hereby incorporated by reference.

Referring further to the drawings, Figures 3A-C schematically illustrate . waterproofing of a foundation of a constructi-on, in accordance with a preferred 5s embodiment of the present invention. A bed 32 of free-flowing hydrophobic aggregate is applied over pebble layer 22, prefesrably remains as a drainage channel under bed 32. Bed 32 prevents water fro-m applying upward pressure onto underground section 14. The hydrophobic saggregate may be delivered to the construction site either in a free-flowing form, or encapsulated in one or protective encapsulations. One example of such protective encapsulation is a hydrophobic brick, as further detailed herein under (see Figure 4A and the description that follows). . Thus, according to a preferred embodiment of the present invention bed 32 may "comprise an arrangement of hydrophobic bricks. ’ Referring to Figure 3B, bed 32 is preferably protected by a structure 23, for example, a concrete structure or a polymeriac structure, to prevent erosion by } “underground water.

The thickness of bed 32 (designated d1 ima Figure 3B) is preferably from about 1 cm to about 15 cm, more preferably from abort 4 cm to about 10 cm. However, it will be appreciated that, depending on specific reeds, other values may similarly be used.

According to a preferred embodiment o f the present invention, wall 15 of underground section 14 can also be waterproofe=d by providing a sidewall 30 of the free-flowing hydrophobic aggregate (e.g., aggregate 1) adjacent to wall 15. Objects protruding from wall 15 (nails, metal wires, efc=.) which may penetrate through the hydrophobic aggregate and allow water to flo w thereupon from ground 12 into - underground section 14 are preferably removed fiom wall 18, prior to the construction ) of sidewall 30 but further work on walls is not necessary contrary to prior art method in which the walls have to be carefully prepared tc> accept waterproofing.

Wall 15 is preferably coated by a waterpr=aofing liquid or paste, e.g., tar layer 24. Tar layer 24 (or any alternative waterproofingz substrate covering wall 15) adheres the hydrophobic aggregate to wall 15 hence serwves as a vapor barrier, preventing a . formation of gap between sidewall 30 and wamll 15. One would appreciate the advantage of preventing the formation of such a gag because water may flow into the : gap from above.

With reference to Figure 3C, sidewall 30 of the hydrophobic aggregate is _ preferably preotected by a structure 36, which may oe, for example, one or more wood 5 . boards, polyrmneric (e.g., polystyrene) boards, plastics boards, metal boards, a brick wall or a concrete structure. Structure 36 is interposed etween sidewall 30 and ground 12 (or pebble layer 22) hence serves for protecting sid~ewall 30 from erosion, roots, rocks and the like. Preferably, structure 36 has a non-snmooth surface 37, facing ground 12 or pebble laser 22 for so as to enlarge the contact area between structure 36 and the ground.

The onstruction of sidewall 30 may be dorme by more than one way, as further detailed here=in below, both to a an existing structur—e, during repair procedure, andtoa new structuree, during its construction.

In exzisting structures, prior art methods typically include the use of foam or swollen mateerials injected along the existing walls into the interface between the wall and the groumnd surrounding the wall. In extreme Cases the area near the underground wall is exposed or vacuumed using heavy machinery, so as to allow access to the - external side of the wall. The wall is than waterpr=oofed by a sealing material, such as elastomeric concrete or various foams. These methods, however, are expensive, complicated , and fail to provide a long-term solution to the moisture problem.

According to a preferred embodiment of —the present invention, underground wall 15 cam be waterproofed by the following p-rocedure. First, a layer of ground adjacent to t=he external side of wall 15 is pulled ovat or vacuumed, leaving a gap of air, and second the gap is filled with the free-flowings hydrophobic aggregate. The free- flowing nature of the hydrophobic aggregate allows for a substantially complete filling of the gap, i_n contrast to any other foamy or swoll=en material which does not allow an airflow theree through, hence entrap air pockets ance cannot fill the entire gap.

In ne=w structures, structure 36 is preferabl=y constructed adjacent to wall 15, in a manner thmat a gap is formed between structure 36 and wall 15. Subsequently, the gapis filled with the free-flowing hydrophobic ageregate, preferably from the top side, as further detailed hereinabove.

Struecture 36 may be made in any way known in the art. Hence, in one embodiment, structure 36 may be an additional w~all, e.g., a brick-concrete wall. The advantage of this embodiment is that the additional wall ma aintains the hydrophobic aggregate in place for a prolonged period of time. Addi tional advantages of the additional wall include additional strength to the constrwction and an enhanced isolation (both thermal and acoustical).

In another embodiment, structure 36 may be made of tiles (e.g. plastic tiles) having tootheed edges, which fit into each other, tongue amnd groove fashion. This embodiment has the advantage of holding the hydrophobic as ggregate on a first side of structure 36 mand the ground on a second side of structure 3a6. The toothed edge tiles are further detailed herein under with reference to Figure 9.

In amother embodiment, also suitable for new stmructures, side wall 30 is constructed Level by level as follows. Hard boards or othe=r boards, such as, but not limited to, metal, wood and plastic boards) are temporarily positioned adjacent to wall 15, so that a first side of the hard boards is facing wall 15 (C again, leaving a sufficient gap there between) and a second side of the hard boards is feacing the ground. The gap is filled with the free-flowing hydrophobic aggregate and the ground is allowed to contact the second side of the hard boards. Subsequently, the hard boards are pulled out, preferalboly upwards, and the procedure is repeated for the next level, preferably ) using the same hard boards. In this embodiment, to protect the hydrophobic . aggregate, protecting structure 36 is preferably positioned permanently between the hydrophobic- aggregate and the ground. Alternatively, the h_ard boards may be used as protecting structure 36. The advantages of this embodime=nt are that (i) there is no "need to builcl an additional wall near wall 15 and (ii) the filling of the gap is simpler as to a relatively ssmall volume is filled at each level.

In amy of the above embodiments, the preferred thickness of sidewall 30 (designated ed? in Figure 3C) is from about 4 cm to about 10% cm. It is to be understood "that other va_lues may similarly be used, depending on the exxpected water pressure.

In ar additional embodiment, also suitable for news structures, side wall 30 comprises an arrangement of hydrophobic- bricks, each. comprising a protective encapsulation having a predetermined shape and encapsulating a free-flowing hydrophobics aggregate.

Figuwes 4A-B schematically illustrate a hydroplobic brick 40 having a - protective eracapsulation 41 and a hydrophobic brick wall 422. According to a preferred embodiment: of the present invention encapsulation 41 is mmade from a bio degradable

So oo material oer water degradable material, for example, recycled cardboard devoid of water protection and the like. In this embodiment, the construction of hydrophobic brick wall. 42 is by positioning bricks 40 one on top of the other, similarly to the construction of any other brick wall. In time, when ermcapsulation 41 degrades, the hydrophobic aggregates of adjacent hydrophobic bricks are partially mixed, so that a substantially waterproof sidewall is formed. Once completed, wall 42.is preferably watered imm order to facilitate the degrading of bricks.

Ome or more layers of bricks may be used. Prefasrably, the brick thickness, in the directi on of water protection, d3, is about 2-10 cm, preferably about 4 cm. It will be appreciated that other dimensions may similarly be use=d.

It -is known that structures in contact with the ground are dynamic, due to ground meovements or crack formations. Thus, accordirg to a preferred embodiment of the present invention, irrespectively of the method by which sidewall 30 (or brick wall 42) are constructed, a removable cover 38 is prefer—ably provided on the top side thereof, tow allow the refill of the gap, with time. Remo~vable cover 38 may be made from any water resistant material, such as, but not limi=ted to, waterproofed concrete stones.

Re=ferring further to the drawings, Figures S_A-B schematically illustrate methods Of waterproofing floors 60 of structure 10, in accordance with a preferred embodiment of the present invention.

Structure 10 includes several levels 70 and =side walls 52. Bed 32 of hydrophobic aggregate (e.g., aggregate 1) is applied wmnder floors 60 and prevents water fromn collecting under the floor. A typical thickness of bed 32 for this aspect of "the invention is about 1-10 cm, however, it will be appreciated that other values may similarly be used. Contact area 52' between wall 52 an-d bed 32 is preferably coated by a waterproofing liquid or paste which adheres the hyd-rophobic aggregate to wall 52 hence serves as a vapor barrier, as further detailed hereinabove. . A pipe 68 (e.g., water, sewage, gas, electricit-y, etc.), if existing, may be embedded. in bed 32, for example, under floor 60. The sadvantage of the hydrophobic aggregate is that it allows water to evaporate there thr-ough without becoming wet.

Thus, if, feor example, leakage occurs from pipe 68, once such leakage is repaired and excessive water is sponged or removed, the hydrophobicc aggregate remains dry, thus avoiding ssituations of wet floors, mildew and health rel ated implications of wetness.

This eadvantage is not found in prior art methods vevhere the water is trapped unde-r the floor for a long time. A particular advantage of th_e present embodiment is that dvae to the immproved isolating properties of the free-flowirg aggregate, no additional isolating materials are necessary for the pipes as is commosnly used for hot water pipes o=x the s like. Mn addition, the free-flowing aggregate protec=ts the pipes also from corrosiorm and wear.

Another advantage of using bed 32 under floor 60, is that such an environment keeps away insects and other organisms which caannot dig holes or tunnels, or «even surviv-e in the dry environment of the hydrophobic aggregate.

An additional advantage is the thermal ard acoustical isolation providesd by bed 322. Thus, for example, bed 32 is ideal as a b-ed for placing hot/cold water pdpes, : for which it will be appreciated that thermal isolatieon is of utmost important.

Reference is now made to Figures 6A - 6B —which schematically illustrate p-rior- art m_ethods of waterproofing a roof 50. Nuwumerous methods are known for waterproofing roofs. One such method is illustrate=d in Figure 6A, where a layer 54 of tar is applied to roof 50. Another method is illustrated in Figure 6B, where a layer of ordinary sand S8 and flooring 60 is applied ontow roof 50. Additionally, protective sheets 56, for example bituminous membranes, powlyvinyl chloride (PVC) or ethy~lene propyl ene diene monomer (EPDM) layers may be used under layer of sand 58.

Howewer, none of these are fully satisfactory, a_nd water problems from roofs, in . partictalar flat roofs, are common.

The present invention successfully and advantageously addresses the issu-e of waterpsroofing a roof. Figure 7 schematically illusxtrates structure 10 having a roo f 50 and sidewalls 52.

According to a preferred embodiment of the present invention, bed 32 of hydropehobic aggregate (e.g., aggregate 1) is applied onto roof 50 and remains - contairaed by sidewalls 52. Preferably, prior to the= application of bed 32, the con=tour of roof 50 may be treated by providing vapor barrier and inclined edges, as is well known in the art. Additionally, floor 60 may be applied over bed 32, thus preventing erosiors thereof. In this manner, a high-level water-proofing protection is achie=ved even om severe weather conditions such as hail. Tzhe thickness of bed 32 (designated d4 in Figure 7) is preferably about 5 cm. It will be appreciated that other values rmay similardy be used.

Co Ess

According to an additional aspect of the present invention, there is provided a method of waterproofing a reservoir, e.g., & water reservoir.

Referring further to the drawings, Figure 8 schematically illustrates a reservoir 80 having a base 82 and walls 88, which may be sloping walls or vertical walls. 5s According to a preferred embodiment of the present invention, the method comprises the following method steps in which in a first step a flooring bed 84 of a free-flowing hyd-rophobic aggregate (e.g., aggregate 1) is placed over base 82 o-f the reservoir. In a . second step, walls 90 (sloping walls or vertical, depending on thee shape of reservoir 80) of the hydrophobic aggregate are placed over walls 88. Flooring bed 84 and/or walls 90 are preferably covered by protective structure 86 and 92 _, respectively, so as to maintain free-flowing hydrophobic aggregate in place. Preferabely, & minimal depth of about 5-10 cm is maintained between structure 86 and basse 82 and between structure 92 and walls 88 for the hydrophobic aggregate. : Structure 86 (covering bed 84) preferably comprises a flexible layer, for exarmple, a geotechnic fabric, covered by a concrete slab, of prefemrably about S cm in thickness. Alternatively, the flexible layer of structure 86 may be covered by concrete tiles Still alternatively, a portion of the flexible layer of structure 86 may be covered by concrete tiles and another portion may be covered by a concrete slab. According to . a preferred embodiment of the present invention the concrete is povred on the flexible layer devoid of metal wiring, to prevent flowing of the hydrophob®c aggregate during "the ceonstruction of structure 86. Polymeric fibers may be added to #&he concrete mix to miniznize crack formations in the structure 86. The pouring of th e concrete may be done in any way known in the art, preferably by leaving a sufficient number of gaps to allow the concrete to expand during its curing process.

Structure 36 may also be made of a plurality of protective b=oards or any other method known in the art.

The method for placing walls 90 depends on the shape of walls 88 of reservoir 80. For vertical walls, walls 90 may be constructed similarly to —walls 30 or 42 as furthest detailed hereinabove.

For sloping walls, a sloping structure 92 is constructed. This may be done, for ‘exampole, by placing various stabilizing means, such as, but not limit-ed to, nets or nets covereed with cloth, and then pouring the free-flowing hydrophobi_c aggregate from above. A_s stated, the hydrophobic aggregate allowss air to flow there through without formation: of air pockets.

Fi_gure 9 schematically illustrates a representative example of stabilizing means, in the form of tiles 98 with toothed edges 99, which fit into each other, tongues 5s and groowwe fashion. Tiles 98 may be made from polyvinyl chloride, polycarbonate ox any other= suitable material capable of holding the hydrophobic aggregate. The siz-e and stren_gth of the tiles is preferably selected so ams to allow the installer to walk omr stand thesreon. Several elongators 97 (e.g., screws) are preferably attached to the tile=s so as to Create a sufficient gap between the tiles arad the ground. A typical length oof elongator=s 97 is 1-10 cm.

The procedure of constructing sloping structure 92 using tiles 98 is as followss.

A first lime of tiles is arranged on sloping wall 88 mear base 82, so that elongators 97 ~ keep tile=s 98 above the walls. The volume defined by elongators 97 is then filled with the hydr-ophobic aggregate. According to a preferred embodiment of the preset inventior tiles 98 may be manufactured from a trarsparent material so as to allow time installer to verify that the entire volume is filled, and to vibrate the tiles if necessarzy, - 50 as to boetter distribute the hydrophobic aggregates. Mechanic or sonic vibration mamy also be used. Once the first line is filled with the hydrophobic aggregate, a second lire is arrangzed adjacent to the first line, and the procsedure is repeated. According to a preferred embodiment of the present invention, once a line of tiles is filled, tie elongato=rs of the previous line are removed so as &o allow the hydrophobic aggregate © to fill the volume engaged by the elongators. : Once wall 88 is covered by tiles 98 and the hydrophobic aggregate, concrete cor another =suitable cover is preferably be applied on the other side of tiles 95. Toothe=d edges 99 serve for increasing the surface area of tiles 93 so as to maintain tke hydropheobic aggregate and the concrete in place a nd to allow spray shot crating if so desired. The upper line of tiles is preferably perrmanently attached to the ground —to serve as _a protective cover.

My ccording to a preferred embodiment of the present invention the tiles are arranged: in a manner that allows refilling of the free-flowing hydrophobic aggregate with tim_e. This can be done, for example, by leaving openings in the upper line eof : tiles or bey providing a removable cover thereupon, as further detailed hereinabove.

The compositions, particulates and free-flowing aggre-gate of the present invention can alseo be used in the area of agriculture or gardening where it is often desired to prepares an area for plants cultivating. It is known that only a relatively small part of wate=r used for irrigation finally arrives to the plants, whereby most of the water seeps throu_gh the earth or evaporates.

Accordingz to a preferred embodiment of the present iravention an area of interest can be prepared for plants cultivating by providing a bed of free-flowing hydrophobic aggmregate (e.g., aggregate 1) onto the area of intemrest and covering the bed by a layer oef soil. Additionally one or more water collec=tion channels can be positioned in, unader or above the soil for allowing conveyance om f water. The bed can be in a form of hydrophobic patches, made of a protective encapsulation and encapsulating thee aggregate. The patches are preferably arranaged such that one or more spaces are #ormed between adjacent patches, thereby allowZing excess water (e.g., rain water), to dr=ain of the area of interest.

Since the hydrophobic aggregate is dry and presents a lovov resistance for vapor, the bed can conduct a passage for vapor undemeath the trees or— plants. This effect is further enhanced by the sucking action of the roots. When water is evaporated under and through the hydrophobic bed and condenses again due tos temperature changes with time, the Shydrophobic bed traps the condensed water and prevents it from escaping again. ‘Thus, water percentage in the top soil layer rise-s. The effect of vapor and water trappimng can be increased by positioning a layer of supper absorbent polymer : on the hydropholbic bed so as to utilize a larger proportion of vapor. : According to a preferred embodiment of the present inve=ntion the layer of soil is surrounded bey a protective barrier, which itself can be mmade of hydrophobic aggregate as fumrther hereinabove. In this embodiment, the wevalls of the protective "barrier and the bed form an enclosed reservoir, preventing the condensed water from escaping therefreom. The height of the walls can vary as desired, depending on the amounts of condensed water, soil type and underground water le=vel.

One of oordinary skill in the art would appreciate that= the hydrophobic bed facilitates desal=ination of non-desalted water present thereumnder, because vapors, passing through the bed are substantially desalted, hence, upon econdensation the water is being desalinaated.

The hydrophobic bed can also be used in a preparation of a salt-fre=e area on a salty soil. In many places around the world, underground water level Ms high and water is salty. This presents a Teal challenge both for agriculture and construction applications. Thus, according tO a preferred embodiment of the present invention a salt-free area can be provided by providing a hydrophobic bed onto the are=a of interest and covering the bed by salt-free soil. The bed prevents the salt from penetrating therethrough and at the same time facilitates passage of (non-salty) water vapor, in the aforementioned desalination process. Optionally and preferably, to e=nhance the capturing of vapor passing through the hydrophobic bed, a layer of supest absorbent polymer can be used, to allow formation of gel, as further detailed above. It would be : appreciated that the use of hydrophobic bed of the present embodiment as a barrier : "against salts is advantageous ov er conventional methods in which barrie=r sheets are - used, because there are no joints or welded parts.

Bh According to a further aspect of the present invention there is provided a "15 method of protecting an object buried underground. In applications ira which the ) hydrophobic aggregate is used for protecting underground objects, it is particularly useful to mix two or more [ree-flowing hydrophobic aggregates. It is to be understood, however, that it is not intended to limit the scope of the present invention

BE to any number of hydrophobic aggregates (i.e., one, two, three or more Enaydrophobic aggregates can be used).

Thus, according to another aspect of the present invention, there is provided a hydrophobic composition for protecting an underground object, generally referred to herein as composition 110.

Referring now again to the drawings, Figure 10 is a schematic ilMustration of composition 110 which comprises a mix of at least two free-flowing Iydrophobic aggregate, each of which may posses one or more properties of aggregate 1.

Preferably, composition 110 comprises a thermally conductive #fice-flowing “hydrophobic aggregate 112 and a dielectric free-flowing hydrophobic aggregate 114. ) Aggregates 112 and 114 are mixed in a predetermined ratio which is selected so as to electrically isolate the underground object while allowing transportat=ion of heat therefrom. According to a prefexted embodiment of the present invention ecomposition 110 has a distinguishable color, preferably different than the color of the gr-ound.

. Before providing a further detailed description of methods of protecting underground objects, as delineated hereinabove and in accordance with the present embodiments, attention will be givem to the following advantages offered thereby.

First, being substantially dry, both aggregates prevent electrolytic processes (such as electrolytic corrosion) from occurring near the underground object. Even in cases where water vapors percolate through composition 110, these are not sufficient to initiate electrolytic corrosion.

Second, as hydrophobic aggwegate 114 is made of a dielectric material (i.e., has substantially no electrical conductivity), connection boxes, oil sensors or any other device filled with composition 110, can function without short circuits for a prolonged period of time. The free-flowing form of composition 110 facilitates the removal of the aggregates from the wires and/or the connection boxes, if such a removal is needed, e.g., for maintenance.

Third, the ohmic resistance of conductors being present in connection boxes, and of cables and wires carrying electrical current is known to release energy by generating a substantial amount of heat. The resulting temperature increase often

E . contributes to weakening of both the current carrier and its surrounding non- conducting elements. It is appreciated that lack of a proper heat transport mechanism may results in electrical discontinuities along the wires and cables, especially inside the connection boxes, where most of the heat is generated. Furthermore, in small connection boxes, the generated heat may cause fusion of several conducting elements thereby to create short circuits and «damage the systems depending on the underground } cable, The thermal conductance of aggregate 112 allow composition 110 to transport heat away from the current carxier (e.g., to the ground) thereby to keep the .25 underground connection boxes, cables and/or wires cool at all times and to maintain their functionality. ) Forth, various agents, and especially digesting agents, present in the ground in solid state are prevented from becoming liquefied and therefore from reaching and damaging the underground object.

Fifth, the free-flowing form of the aggregates of the present invention : minimizes axial stresses from actirag upon the underground object. In other words, . although being made of solid particulates, in terms of dynamical properties, the free- flowing hydrophobic aggregates are similar to a viscous fluid, which uniformly

: distribute=s the mechanical forces acting thereupon. The aggregates of the present invention thus absorb a considerable amount of &the mechanical forces and protects the . undergrotand object.

Si-xth, being substantially water-free, the hydrophobic aggregates do not freeze s and does not stick, hence facilitate an easy access to the underground object in co-1d regions, and improves resistance to frost.

Se=venth, as stated, in one embodiment composition 110 has a distinguishable color. “This embodiment can be beneficial 1y used when an identification of composition 110 is required. For example, for the purpose of warning agairst excavatio:n near the submerged object which is ceovered by composition 110.

Ei’ ghth, underground oil tanks often su_ffer from oil spills resulting from a leaking tzank or an overflow. To monitor smich leaks, one or more sensors mre positionecd near the underground oil tanks so as to generate a signal when the surroundi-ngs of the sensor become wet. These ssensors, however, often generate fal se alarm dues to the presence of, e.g., rain water. A_s stated, the composites of the prese=nt invention can have an increased attraction for o~il and oil related products. Thus, the aggregate=s of the present invention can be useed to selectively prevent water fro-m gy reaching t=he sensors, hence substantially reducin.g the false alarms. . According to a preferred embodiment of tthe present invention any free-flowirag hydrophobic aggregate may be used for aggregat es 112 and/or 114, provided they hae © the requir=ed properties, i.e., enhanced thermal co-nductance of aggregate 112, enhanced : electrical resistivity of aggregate 114 and enhanced water repulsion for both aggrega-te © © 112 and a_ggregate 114.

Time ability of any hydrophobic material teo repel water basically depends on thkhe surface te=nsion of the liquid being in contact with the hydrophobic material. In amy liquid, thes cohesive forces between molecules gpresent deep in the liquid are shared with all neeighboring atoms. The surface molecumles of the liquid have no neighborirag atoms of t=he same type above and exhibit stronge=r cohesive forces upon the molecules directly asssociated with them on the surface. From a macroscopic point of view, the enhanced intermolecular interaction at the surfZace of the liquid is observed as thie surface termision of the liquid.

Th_e cohesive forces between like mole=cules compete with extemal forces existing beetween the molecules of the liquid and. molecules of the material contactimg the liquid. When this material is hydrophobic, the cohesive forces significantly . dominate, the free surface of the liquid becormes film-like and the liquid is incapable of wetting the hydrophobic material.

Hence, depending on the maximal liquid pressure expected near the 5s underground object, aggregates 112 and M14 are preferably selected such that the cohesive forces are sufficient for preventing the liquid from wetting composition M10.

Any of the aforementioned hydrophobic aggregates, may be mixed in - composition 110, according to preferred e=mbodiments of the present inventiorn. In particular, the core material is preferably~ selected in accordance with the desired property of the free-flowing hydrophobic saggregate. For example, sea sand m_ay be used as the particulated core material for ®hermally conductive aggregate 112, while : coal ash may be used as the particulated comre material for dielectric aggregate 11<%.

According to a preferred embod iment of the present invention each of aggregates 112 and 114 of composition 110 may comprise differently sized “15 particulates characterized by several parzameters which influence the hydrophobic properties of composition 110. These pa rameters may includes the aforemen tioned size distribution, M, a contact angle, 0.

As stated capillary sizes may Wbe significantly reduced using inflatable particulates, which, in one embodiment can be integrated in, or attached to the particulates of aggregates 112 and/or 114 . Alternatively, inflatable particulatess cane . be in the form of free particulates (e.g., a gpowder). Referring now again to Figure 10, an inflatable particulate 116 is present in a void 118 between particulates of aggwregates 112 and 114, similarly to the way the i-nflatable particulate was incorporatesd with aggregate 1.

According to another aspect of the present invention there is provided a method of protecting an underground object (e.g., a tank, a cable, a wire, a metwork etc.). The method comprises the following method steps which are illustrated in the flowchart of Figure 11. In a first step of the method, designated by Block: 122 a hydrophobic composition (e.g., composition 110) is provided, and a secormd step, designated by Block 124 the object is surrounded by a layer of the hydrophobic composition in a manner that the layer— is interposed between the object and the ground. The second step my be performe=d in any way known in the art, for example, by forming a ditch in the ground, a.pplying a first layer of the hydrophobic composition in the ditch, placing the object on the first layer and covering the= object with an additional layer of the hydrophobic composition. The upper layer of the hydrophobic composition may be subsequently covered by a layer of grasund to prevent the composition from carried by the wind or the rain.

Figure 12a schematically illustrate an object 130 buried in ground 1332, and surrounded by a layer 134 of the hydrophobic composition, in accordance vith the present invention.

When the und _erground object is an oil tank, one or more sensors 129 ~may be positioned near the «object within layer 134 so as to monitor possible oil spills.

According to the presently preferred embodiment of the invention, the hydrophobic composition is selected so as to allow absorption or adsorption of oil therein, Imence to facilitate proper operation of sensors 129 with minimal false alarms. This can be done, for example, by selecting the core material so as to maximize the adsor=bing or absorbing capability of the aggregates. Representative example, for such core rmaterial includes, without lirmitation, granolas of cellulose which can provide abeout 1:1 absorption capability.

This embodiment is particularly useful, e.g., for prevention the generation of false leakage alarms aus further detailed hereinabove.

The problem of oil spills also exist in above ground oil tanks wimich are typically positioned within a dike to prevent oil spills from reaching the soil urader the dike. However, over the time, these dikes are filled with rain water, in which case the oil spills overflow fro=m the dike, hence contaminating the ground.

Reference in mow made to Figure 12b which is a schematic illustratio=n of an object 131 (e.g., an oil tank) positioned in a dike 135. According to a pmreferred embodiment of the preesent invention the surroundings of object 131 within dikee 135 is filled by a layer 133 «of hydrophobic particulates (e.g., aggregate 1, compositi=on 110, etc.). Preferably, the core material of the hydrophobic particulates is selected =so as to maximize the adsorbimg or absorbing capability of layer 133. Thus, while water drops 136 are repelled from layer 133, oil spills 137 are attracted thereby, hence causing the water to overflow frorm dike 135 and keeping the contaminating oil therein.

According to another aspect of the present invention there is prowided a method of manufactu-ring a hydrophobic composition for protecting an undem-ground object. The method ccomprises the following method steps which are illustratesd in the flowchart of Figure 13. In a first step of the method, designated by Block 142 a thermallss conductive free-flowing hydrophobic aggregate (e.g., aggregate 112) is provided, in a second step, designated by Block 144 a dielectric free-flowing hydrophobic aggregate (e.g., aggregate 114) is provide and in a third step, designated by Block: 146 the two aggregates are mixed. As furtiner detailed above, the mixing ratio of the two aggregates is selected so as to allow “both electrical isolation of the undergromund object and transportation of heat therefrom.

According to a preferred embodiment of the pressent invention the method may farther comprise an optional step, designated by Bl-ock 148, in which inflatable particulates (e.g., particulates 116) are mixed with the thermally conductive and the dielectric free-flowing hydrophobic aggregates, as further detailed hereinabove.

Optionally and preferably, the method may further comprise an additional step, designated by Block 150, in which the two aggregates and the inflatable particulates in the embodiment in which these particulates are incBuded) are mixed with one or more additive, such as, but not limited to, a coloring agent, a UV resistant agent, a bleaching agent and an abrasive agent, as detailed above.-

Additional objects, advantages and novel featuress of the present invention will become apparent to one ordinarily skilled in the art upon_ examination of the following examples, which are not intended to be limiting. Add=itionally, each of the various embodiments and aspects of the present invention as delineated hereinabove and as claimed in the claims section below finds experimental support in the following examples.

EXAMPLES

Reference is now made to the following exampiles, which together with the above descriptions illustrate the invention in a non limitingg fashion. : EXAMPLE 1

Preparation of a Hydrophobic Powder — Germeral Procedure

As is described hereinabove, the hydrophobic powder of the present invention includes orae or more selected impure elements that heave a hydrocarbon attached thereto a-nd optionally hydrophobic fumed silica. The composition of the hydrophobic powder &.s predetermined according to the desired application.

SE Tn cases where the selected hydrophobic powder does not imnclude hydrophobic fumed silica, the hydrophobic powder is preferably prepared by a surface reaction of s colloidal particles of one or more selected impure element (e.g, calcium carbonate, magnesium carbonate, calcium oxide, etc.) with a fatty acid havin _g at least 10 carbon atoms im its hydrocarbon chain, to thereby obtain a hydrophobic derivative of the element in a powder form. A representative example of such a hydrophobic powder is

Calciunn Stearate, which is a commercially available powder that is presently used in pharmaceuticals and plastics. However, such a hydrophobic poweder can be prepared, for exaznple, by contaminating calcium carbonate with impurities such as magnesium oxide, ron oxide, aluminium oxide, silica and sulfates, and thesreafter reacting the resulting impure calcium with stearic acid.

In cases where the hydrophobic powder further includes hydrophobic fumed silica, the resulting hydrophobic powder mixture is prepared by mixing predetermined amounts of each of the components until uniformity is attained. The mixing is typically continued for about 10 minutes.

A representative example of a hydrophobic powders acceording to the present inventi on include a mixture of Calcium Stearate having an avertage particles size of about 10 microns (obtained from Kfar-Gilaadi Quarries, Israel) and hydrophobic fumed silica having an average particles size not greater than 1 micron (Aerosil Fume . Silica, R-812, by Degussa, Germany). The calcium stearate andll the fumed silica are mixed for about 10 minutes and the resulting hydrophobic po~wder has an average : particlees size not greater than 10 microns.

EXAMPLE 2

Preparation of Hydrophobic Composites ~ General Procedure

Drying the core material: The core material (as is defined hereinabove) is dried et a temperature of at least 104 °C, until its moisture level is reduced to below 1 weight percentage. This procedure is carried out in a closed mixing vessel equipped with a suction port fitted with a valve enabling opening and clo sure. Alternatively, a pre-dr-ied core material is placed in the mixing vessel described above and is heated to a a temperature of at least 70 °C.

W/O 2005/005566 PCT/IL2004/000635

Coating the core material with an adhewent layer: Preliminary preparation of tte adherent layer mixture is carried out in a m3xing vessel at a temperature of 40-90 oaC, during about 10 minutes (the compositiora of the mixture is determined as is d_escribed hereinabove). The adherent mixture is then added hot as it is into the naixing vessel described hereinabove, which contains the dry core material. The ressulting mixture of the dry core material and time adherent layer mixture are thereafter meated and mixed, preferably at 30-60 rpm, such that the solvent is evaporated using . the suction system described above. Alternatively, this procedure is carried out vwvithout heating, by utilizing the self-heat of the core materials, which is formed during the drying process. This procedure continues until the solvent content reaches 0 % and typically lasts 10-45 minutes, dependings on the type of solvent used in the adherent layer mixture. The evaporated solvent (e.g., an organic solvent) can be recycled for repeated use, both in order to pprotect the environment and from an economic standpoint.

In cases where other additives are added to the hydrophobic composite (e.g. coloring agents, abrasive powder, UV resistance agents etc., as is detailed

Inereinabove), the additive is added to the mizing vessel at this stage and mixing is continued, preferably at 30-60 rpm, for additional 5 minutes, to obtain uniformity. “The added materials should be dried, so as to have a moisture content of less than 1 %.

Coating the core material coated with he adherent layer with a hydrophobic mowder: The hydrophobic powder is prepared as described hereinabove in a separate wessel. The resulting hydrophobic mixture off choice, as is detailed hereinabove, is zadded into the core material mixture. Upon acldition of the hydrophobic mixture, the '. =suction port is closed in order to prevent loss Of the hydrophobic material. Mixing is econtinued for about 10 minutes, until the pow~der cloud completely disappears. The "resulting mixture is then cured for between 2<% hours and 30 days, depending on the sselected hydrophobic mixture, so as to produce the final hydrophobic composite.

The total time of the process between obtaining the dried core material and «obtaining the core material coated by the hydrophobic powder ranges between 25 and «60 minutes.

EXAMPLE 3 . Preparation of Hydrophobic Composites in a Cold Process — General PProcedure

The core material is dried as is described hereinabove to reamch moisture content less than 1 %. The dried core mater-ial may be stored in a closed dry place to be used for coating when cold, without any need of re-heating.

An adherent layer mixture, which preferably comprises in this preocedure 7% polyurethane and 93 % ethyl acetate, is prepared as described above and i_s then added . to the dried core material. The quantity of the obtained adherent layer in. this process typically ranges between 3 and 7 weight percentages of the dry core material weight.

The resulting mixture is mixed at room tenperature, for about 10 minutes, until the ethyl acetate is vaporized down to a level of O %. The evaporated ethyl acetate may be recycled up to about 80 % of its content.

A hydrophobic coat mixture of choice is then added as is describe=d above and the resulting mixture is mixed for about 5 mimutes.

The final product is obtained after curving between 24 hours and 30 days.

EXAMPLE 4

Preparation of Hydrophobic Sand

Sand, such as, for example, quartz sand having particles size of 600-800 microns, was dried as is described hereinabove.

In a separate vessel, an adherent mixture containing 9 weight percentages of the polyurethane Alkydal F 48, 55 % ira benzene-xylel (obtained rom Bayer,

Germany), 5 weight percentages of commercial liquid asphalt (Premier 14230, obtained from Paz-Kar, Israel) and 86 weight percentages of toluene (obtained fromm Frutarom,

Israel) was mixed, at 70 °C, for about 10 mimutes and was thereafter added to the hot . sand. Mixing was continued for about 15 minutes, at 50 rpm, during which the toluene content was reduced to 0 %.

A hydrophobic powder comprised of between 14:1 and 3:1 Calcium Stearate (obtained from Kfar-Gilaadi Quarries, Israel) and hydrophobic fumed sil=ica (Aerosil

Fume Silica, R-812, by Degussa, Germany) was prepared in a separate vessel by mixing the components for about 10 minut«es and was thereafter added to the hot -fmixing vessel containing the sand coated by the adherent layer. The suctieon port was closed and mixing was continued for about 10 minutes at 50 pm. The product was then cured for 3 Qdays.

EXAMPLE § s Preparatiorm of Hydrophobic Sand Enhanced With a Surf-eit of Free Particles

In a seamcch for hydrophobic sand having improved resistance to dynamic water, it was found thant using an increased amount of the adherent la-yer, (e.g., up to 2 weight percentages of the dry aggregate) as compared with the amount indicated in the presently known procedures for preparing hydrophobic compeaosites (see, for example,

U.S. Patent Nos. 4,474,852), results in enhanced resistance of the hydrophobic sand to dynamic wear, due to addition of small hydrophobic particles —to the hydrophobic sand.

This erxhanced resistance occurs as a result of the Following: when a water wave hits the hydrophobic sand, it pushes the grains somewovhat apart and when the wave retreats a momentary under-pressure is created, which pulls out the lightweight granules first. This “migration” of the lightweight particles is only carried out due to dynamic motion and the particles move towards the dynanmic disturbance, so as to form a thin crust of hydrophobic particles forming an additional protection layer. On account of the strong hydrophobic property of the crust, the retreating water does not pull away this crust and the next wave will then encounter a double hydrophobic defense line.

It was found that such lightweight particles may toe achieved by using an excessive ameount of the adherent layer. In this man=ner, the adherent layer ~ components, which do not adjoin the sand, form free, light pearticles having a size of I~ 50 microns. “These particles become hydrophobic in the se=cond stage, together with the sand granuales, and as they are much lighter in weight thean the sand granules, they are attracted first to the momentary under-pressure followings the wave and thus form the described ecrust.

A deta=iled exemplary procedure of preparing such hyecirophobic sand, improved with free parti cles, is as follows: .

Quartz= sand, obtained from a quarry, having particless size of 600-800 microns, was dried as iss described hereinabove.

In a separate vessel, an adherent mixture containing 15 weight percentages of the polyurettmane Alkydal F 48, 55 % in benzene-xyle_l (obtained from Bayer,

So So

Germanwy), 5 weight percentages of commercial liquid asphalt (Premier 1430, obtained from Pazz-Kar, Israel) and 80 weight percentagess of toluene (obtained from Frutamom, :

Israel) was mixed, at 70 °C, for about 10 minutes and was thereafter added to the hot sand. Mixing was continued for about 15 minutes, at 50 rpm, during whicha the toluene content was reduced to 0 %. The armount of the resulting adherent Layer deposite d on the sand was 2 weight percentages of the dry sand.

A hydrophobic powder comprised of 14:1 Calcium Stearate (obtained from

Kfar-Gillaadi Quarries, Israel) and hydrophobic fumed silica (Aerosil Fume Silica, R- 812, by- Degussa, Germany) was prepared #An a separate vessel by mixing the componeents for about 10 minutes and was themreafter added to the hot mixing vessel . containimng the sand coated by the adherent laswer. The suction port was closed and mixing wwas continued for about 10 minutes at 5#0 rpm. The product was then cured for 30 days.

EXAMPLE™ 6

A Hydrophobict ty Test

When hydrophobic sand is serially rmanufactured, on-going tests of the hydroph-obic quality of the finished product are required. The presently kmown methodss measure the contact angle or the surface energy of the produced hydroplaobic sand. HC owever, although when properly applieed these two methods are accurate and . Ce reliable, they require expensive and delicate equipment such as a microscopre, a : computer and optical equipment and therefore these methods are suited for the laboratomry but not for ready and rapid productior-line application.

Since the required test is comparativwe and intended to compare sirmilar productieon batches in regard to their hydrophobic characteristics, an easy, tdme- consuming and cost-effective test method is required and has been designed, as follows: 2M glass beaker is filled with water up to “half its height approximately. A small funnel (“sand glass”) is placed above the water ssurface. The glass beaker is placed on an electr-onic balance and the balance is zeroed. Hydrophobic sand is then addesd to the funne=l until the sand lump falls into the watesr. The balance indicates the weight of the hydrophobic sand for comparison.

. The underlying principle of th is designed test is as follows: Since the sand is hydrophobic, it changes the surface tension of the water so that the sand floats on top of the water. The weight of the hxydrophobic sand is practically balanced by the surface tension. Hydrophobic sand- atiempts to reach the minimum contact area possible with the water so that the samd grains cling to one another and the sand lump directs itself towards the beaker center. The small funnel is constructed such that the streaming of the sand is practically constant and the closeness of the nozzle to the water warrants a practical “floating of the sand and hardly transfers any kinetic energy which could drop down the sand lump prematurely.

In order to compare various ssand samples under identical conditions, as far as possible, the following rules should twe observed:

The water must come from th_e same source, and should preferably be distilled; : The water temperature must te identical in all sample tests;

Testing must begin when time water is in static conditions, preferably in an enclosed space;

All other test data must be ideentical (beaker, funnel, sand, etc.);

A number of tests must be camied out in parallel, observing the statistical sampling rules.

The test can be carried out a=utomatically by inserting an electric stopper at the ot 20 funnel nozzle, and a detector that inclicates the exact moment when the sand lump falls and then halts the sand flow by meas of a shutdown valve.

EXAMPLE 7 .

Corrosivity Test

In order to verify the protection capability of the hydrophobic sand of the present invention against corrosior of iron, the following corrosivity test has been performed:

Into a container filled with ssea-sand, three standard polygonal reinforcing iron construction bars of 10 mm diameteer were inserted. The three bars were of identical © 30 length and weight. The first bar was dressed with concrete throughout its length in a diameter of about 10 cm, apart from the tip of the bar, which was left exposed for electric connection. Based on thes assumption that corrosion level within cast and impacted concrete would be minim al, this bar was intended to serve as control against the twa other bars and is referred to hereinafter as control bar. The second bar was left in its matural state and sunk into the sea sand as is, apart from its tip which was left expose=d for electric connection, and is referred to hereinafter as natural bar. The third bar wzas sunk in sea sand surrounded throughout its length with the hydrophobic sand 5s ofthe present invention (prepared as descr-ibed in Example 4) in a diameter of aboumt com, apart from the its tip which was left exposed for electric connection, and is referrexd to hereinafter as hydrophobic bar.

The second (natural) and third (hydrophobic) bars were electrically connected to the concrete-encrusted bar (control) throvagh 100 ohm resistors. 10 The sea sand was wetted with watesr including 8 % sodium chloride, added in order to accelerate the corrosion process. “The sand wetting was carried out once in a - fortni-ght in order to allow natural drying-up by evaporation.

The electric potentials between the =second natural bar (natural) and the controel, as well as between the third bar (hydrophobic) and the control bar, were measured every day. The presently obtained data show that the potential difference between the . naturel bar and the control bar stabilized at a fixed level (about 100 millivolt) thus confirming an on-going corrosion processs in the natural bar, whereas the potential difference between the hydrophobic bar and the control bar remained throughout at zero level, confirming that no corrosion wwas taking place and that the sand indeed proteccts the iron bar against corrosion.

Pulling out the bars afier six months showed no corrosion signs on the hydroophobic bar while the natural bar lost 2.5 % of its original weight.

In order to obtain interim data prior to the above laboratory test, uncoated metal paper clips were inserted into a box <ontaining on one-half ordinary sand and On the other half the hydrophobic sand of the present invention, such that one-half of the clips were immersed in the ordinary sand a nd the other half in the hydrophobic sand «of . the peresent invention (prepared as described in Example 4). The experiment was carrie=d out with 10 identical boxes of such clips. _ In an additional experiment, 10+ pairs of ordinary AAA batteries were submerged in garden soil, whereby one battery of each pair was submerged in the hydrophobic sand of the present invention.

The paper clip boxes were wetted with salt water for about two weeks, where as the bwattery pairs were left buried for ab out two months in the change of seasoms between winter and spring, so that the soil was wetted both with rainwater and with : artificial irrigation, as is the rule for ordinary garden soil.

After two weeks all the paper-clip boxes opened showed an identical result of corrosion and rust in the half of the paper clip b-uried in the ordinary sand whereas the s other half of the paper clip boxes, buried in the hydrophobic sand of the present invention remained intact without signs of corrosion. :

All the batteries buried in regular garden earth showed signs of corrosion at various levels and no electric voltage was measured in these batteries, whereas no sign of corrosion was observed in any battery buried in the hydrophobic sand of the present . 10 invention and the voltage in those batteries was dindeed preserved. : EXAMPLE- 8

Wear Tes

Most of the presently known sealants are usually tested to withstand static water, i.e., water devoid of kinetic energy. At this situation, sealant wear occurs as a result of the reaction between the water and thes material, liquid adsorption, expansion or contraction and as a result of the proliferation of various organisms in the standing water, which also accelerates the wear process Of the sealant.

However, under real conditions, the seal_ant must also stand up against dynamic water, since in most cases water do possess kiretic energy. In every case of wetting, natural or artificial, one can see a vertical or horizontal water motion resembling a : wave. Just as a sea wave that slams onto the beach and causes a breakup of soil and erosion together with its retreat, in wetting, the water wave accelerates the wear of the sealant and such wear is much faster than the w ear caused by static water.

Most of the water motion wear is caussed in nature due to solids transported with the water such as sand, various aggregates etc. Therefore, in order to simulate natural wear, a wearing material such as iron ox<ide powder (Fe;O3) should be added to the water.

Hence, due to lack of data regarding thes effect of real water wear, comparative tests have been conducted, in order to deterrmined the lifetime of the hydrophobic } sands of the present invention, compared with other known sealants, and the required "thickness of the hydrophobic sands of the present invention.

Hence, two sets of tests were carried out: In the first set tests have been conducted in order to compare between layers of pol=ystyrene, PVC, bituminous sheet, the hydrophobic sand of the present invention (see, JExample 4) and the hydrophobic sand improve=d with free particles of the present invention (see, Example 5). In the 5s second set, fi~ve samples of the hydrophobic sand improved with free particles of the present inven-tion (Example 5) having varying thickn_ess between 1 cm and 5 cm were tested for their water wear.

The tests were carried out as follows: A transgparent glass beaker equipped with a screw-dowmn metal lid was provided. Into the met al lid a layer of sponge on which the tested sealant was laid was inserted, so that the ssample extended over the edge of "the glass beaker. Water including 10 % iron powdemr was admitted to the beaker so as to fill one quearter of its area. The lid was screwed d_own on top of the beaker with the sealant samp-le serving as gasket. The closed beakem was placed inverted, with the lid down, so tha-t the water covered the sample.

Five beakers, each comprising a different seealant or the same sealant having "varying thicl<ness, were placed together on a rotary ®umntable driven at an intermediate speed of up to 45 rpm. Since these tests were conmparative, the beakers were driven together, thes water thereby performing a relative circumferential motion around each’ beaker. Beaakers are taken down when the water penetrate the sealant surface and reach the do~wnwards pressing sponge. The total rostation time of each beaker is noted down, consiedering that one water rotation in the gla=ss simulates one wetting cycle or a . single wave_ Since the PVC sheet wear lifetime is Bknown, a coefficient is determined : for the num ber of wettings per day so that the tesst time can be compared based on sealant lifeti-me in months.

The data obtained indicate that the beaker containing polystyrene was taken down after =4 days and further indicate that no watzer has been penetrated the sealant surface in the beakers containing the hydrophobic ssands of the present invention after . two months.

EXAMPLE 9

Dmyrability of Hydrophobic Composites wwnder External Pressure

The capability of hydrophobic aggregatess to withstand water pressure is proportional to the contact angle cosine and is inversely proportional to the capillary radius or the inter-granule clearance radius. Hence, in order to obtain a hydrophobic aggregate that is capable of withstanding high waterr pressure without being cracked or loosing its hydrophobicity, an aggregate having small particle size (such that the inter- : granule clearance radius is minimal) coated by a hydrophobic layer with high contact angle should be used.

In order to measure the capability of hycirophobic aggregates to withstand transitory and continuous pressure, the following te=st has been designed:

A wide and deep pail is perforated at its Woottom with holes that are covered - with a porous cloth, passing water but not sand. The pail is filled with hydrophobic © 10. sand. . The nozzle of a long syringe is cut off, so as to provide a uniform cylinder.

The syringe cross-sectional area is chosen to be 1 cm? for convenience. Rubber bands : are stretched on the syringe external surface, so as to roughen it, and the external surface of the syringe is further covered by a bi-tomenic paste (or any other gluing agent that is not water-based), so as to attach hy=drophobic sand thereto and thereby prevent water passage from the syringe into the hyedrophobic sand.

The syringe is inserted into the hydrophobic sand in the pail, so as to make the distance from the cut-off nozzle to the pail botton serve as the thickness of the tested layer. The syringe is anchored to the pail walls on two sides, such that the syringe ; 20 distance from any wall is larger than the thicknesss of the tested layer, to prevent water from "taking the shorter path". : The piston handle top is widened to enalble it to take weights, and the thus modified piston is accurately weighed. . The syringe is then half-filled with water and the piston is carefully inserted thereto. k By placing weights on the piston top it is possible to measure the pressure in : the long run, as well as to establish the burst-out p-ressure.

Such a test allows performing comparativee tests of the capability to withstand water pressure of various hydrophobic aggresgates, assuming the aggregate is incompressible. This assumption must be cearefully verified for each type of hydrophobic aggregate tested.

As a representative example, the test deszcribed above was performed with a hydrophobic sand prepared as described hereimnabove, having a particles size of between 300 and 600 microns and a hydrophobic powder that forms with water a contact angle of 130 °C.

A weight of 3 kg (including the piston se1f-weight) was placed on the piston for 48 hours. The water head remained unchange=d during this time period. The load was thereafter gradually increased until burst-out Occurred at 4.6 kg.

EXAMPLE 10

Determination of the Adhererat Layer Amount

The core materials that are usable in the h=ydrophobic composites of the present invention are granulated or particulate material s each characterized by a different shape, surface area, absorbency, surface texture and various other mechanical and chemical characteristics. Therefore, different cores materials absorb different quantities of the adherent layer of the present invention unti’1 they become fully coated.

It is therefore desirable to calculate the quantity of the adherent layer required to coat a specific core material, both from an «economic standpoint and in order to ‘produce hydrophobic composites improved Toy “free particles”, which require excessive amount of the adherent layer, as is detamiled hereinabove (see, Example 5).

In order to determine the amount of an eadherent layer that is required to fully coat a certain core material, the following test ha_s been designed:

First, the tested core material is sieved to remove small particles. Measured samples of the remaining material are thereamfter accurately weighed. The core material is then coated by an adherent layer and a hydrophobic powder, as is described hereinabove, whereby the amount of the adheremnt layer is much higher than in typical procedures and the amount of the hydrophobic powder is standard and is accurately weighed. As is described hereinabove (in Example 5), such high amounts of the . adherent layer result in hydrophobic sand having a surfeit of free particles.

The resulting hydrophobic composite is then cured and is thereafter passed again through the same sieve as before to remowe the free particles formed. Measured volumes of samples of the sieved hydrophobic composites are accurately weighed.

The weight of the hydrophobic powder added. is subtracted from the weight of the hydrophobic composite and the resulting weighnt is divided by the initial weight of the sample. The obtained ratio expresses the relative amount of the adherent layer in the . composite.

F-ollowing is a representative example of the described test: oo Common building sand was sieved through a 200 micron rnesh sieve to remove small particles. Three samples, S00 cm?’ each, were weighed, y-ielding the following results: Sample 1 = 812 grams; Sample 2 = 836 grams; Sample 3 = 821 grams; Mean weight == 823 grams.

The sieved sand was thereafter coated by 20 grams of aadherent layer and 1.5 grams of hydrophobic powder per each 823 gram quantity of the mmixture.

After curing, the sand was re-sieved using the same sieves as before to remove free particles.

AAgain, three samples of the hydrophobic sand were veveighed, yielding the followirmg results: Sample 1 = 818 grams; Sample 2 = 839.3 grams; Sample 3 = 832.1 grams; Mean weight = 829.8 grams. oo

Subtraction of the hydrophobic powder amount (1.5), a ratio of (829.8 — 1.5)/823 = 0.64 % was obtained, expressing the amount of adher—ent layer deposited on the core= material in the process. : EXAMPLE 11 . Prepa=ration of Hydrophobic Composites Using a Water-Base-d Adherent Layer —

General Procedure

TFydrophobic composites having a core material and a hydrophobic material bonded thereto via a water-based adherent layer, according to asthe present invention, are geneerally prepared as follows: _Drying the core material: The core material (as is defined hereinabove) is dried atic a temperature of at least 90 °C, until its moisture level is reduced to below 1 weight percentage. This procedure is carried out in a closed mixing vessel equipped with a ssuction port fitted with a valve enabling opening and closure. Alternatively, a pre-drie=d core material is placed in an open fire furnace and is Iaeated to a temperature of at leeast 70 °C.

Coating the core material with a water-based adherent layer: Preliminary preparamtion of an adherent layer mixture containing a water-b-ased gluing agent and : water, Jin a ratio of 1: to 99:1, preferably 1:2, is carried out im a mixing vessel at a temperature of 40-90 °C, during about 10 minutes. The adlaerent mixture is then added not as it is into the mixing vessel described hereinabove, which contains the dry core material. The resulting mixtusce of the dry core material and the adhesrent layer mixture is mixed, preferably at 340-60 rpm, and is optionally further heeated, and thereafter tumble-dried using the immternal heat formed during the reaction, optionally in combination with an external he=at and/or a blower, aimed at increasing the drying rate. This procedure continues until the water content reaches 0 % and typwically lasts - 30 minutes.

In cases where other additi~ves are added to the hydrophobic composite (e.g. coloring agents, abrasive powder, UV resistance agents etc, as is detailed hereinabove), the additive is adde«d to the mixing vessel at this stage and mixing is continued, preferably at 30-60 rpmm, for additional 5 minutes, to obtain uniformity.

The added materials should be drie=d, so as to have a moisture content of less than 1 %. : Coating the core material coated with the water-based adherent Bayer with a hydrophobic material: A selected. hydrophobic material, as is detailed hereinabove, is added into the core material mixtare. Upon addition of the hydrophobic mmaterial, the suction port is closed in order t-o prevent loss of the hydrophobic mamterial. The resulting mixture is then cured for between 24 hours and 7 days, depernding on the selected hydrophobic material, thes temperature and the humidity, so as to produce the final hydrophobic composite.

EXAMPLE 12

Preparation of Hydrophobic Sand having a Water-based Adherent Layer

As representative exampMes of water-based adherent layers, whhich can be efficiently used to bind hydrophobic material to a core material, Bi—tumen-Latex binders and Bitumen-Polymer birders were selected. These binders are commercially available water-based gluing eagents, which are known and typically sold as waterproofing pastes. A numbesr of bitumen gluing agents are presently available, which differ one from the other “by various physical and chemical properties such as . temperature endurance, stability in acidic or alkali environment, ease owf application and the like.

Representative examples of hydrophobic sand having a water-beased adherent layer, and coated by a Calcium Stearate hydrophobic powder, prepared. as described above, were prepared according to the procedures described above, using as the adherent layer a mixture of the following gluing agents and water: Bitumflex (by

Bitum, 4 Ayezira str., Haifa Israel), andl Elastopaz (by Pazkar, Alon Tavor, Afula,

Israel). - The hydrophobicity of the resul-ting composites was tested as is described hereinabove, using a contact angel test. A contact angle of 140° was observed, thus clearly indicating that all the water-based. adherent layer-containing composites can be effectively used in various applications. The high performance achieved with these hydrophobic composites is presumably attributed to the superior tacking force thereof : upon drying. The superior performammce of these water-based adherent layers is . "further attributed to their anionic characteristic, which provides for enhanced entrapment of air, which, as is discusse=d hereinabove, is highly advantageous. It is assumed that the anionic nature forces the Calcium Stearate particles to vertically adhere to the surface, thus achievin g a cage-like structure which enables air entrapment.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in thes context of a single embodiment, may also be provided separately or in any suitable seibcombination.

Although the invention has Wbeen described in conjunction with specific . embodiments thereof, it is evident that many alternatives, modifications and variations- will be apparent to those skilled in the art. Accordingly, it is intended to embrace alk such alternatives, modifications and ‘variations that fall within the spirit and broad + scope of the appended claims. All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference ) into the specification, to the same extent as if each individual publication, patent omr patent application was specifically and . individually indicated to be incorporated hereirn by reference. In addition, citation or i«dentification of any reference in this applicatior shall not be construed as an admissiomn that such reference is available as prior art to the present invention.

Claims (1)

1. © WHAT IS CLAIMED IS:

   1. A hydrophobic composite Comprising a core material coated by a hydrophobic powder, said hydrophobic povevder includes at least one impure elerment havingz a hydrocarbon chain attached thereto .

   2. The hydrophobic composite Of claim 1, wherein said hydrocarbon chain comprises at least 10 carbon atoms.

   3. The hydrophobic composite ef claim 1, wherein said hydrocarbon chain is covanlently attached to said at least one im pure element. 4, The hydrophobic composite of claim 3, wherein said hydrocarbora is a residu_e of a fatty acid having at least 12 car¥oon atoms.

   5. The hydrophobic composite of claim 4, wherein said fatty acid is selecteed from the group consisting of stearic acid, lauric acid, myristic acid, palamitic . “acid, Oleic acid, linolenic acid and arachidomnic acid.

   6. The hydrophobic composite of claim 1, wherein said elememt is select=ed from the group consisting of a metallic element, a semi-metallic element and . a transsition metallic element.

   7. The hydrophobic composite of claim 1, wherein said at least one ) eleme=nt is selected from the group consistimg of magnesium, calcium, aluminum, zinc, sodiumm, barium, zirconium; manganese, titanium, vanadium, chromium, irorax and comb inations thereof.

   8. The hydrophobic compositte of claim 1, wherein said hydrophobic powd_er has an average particle size ranging between 0.02 micron and 50 microns .

   9. The hydrophobic composiste of claim 1, wherein said hydrophobic powd_er has a surface area ranging between_ 1 m* gram and 60 m?/gram.

   82 i

   10. The hydrophobic composite of claim 1, characterized as beings inactive toward alkaline reaggents.

   11. The hydrophobic composite of claim 1, being capable of p reventing water adherence th-ereto and water penetration therein under an external pressure of up to about 4.5 atmosypheres.

   12. The= hydrophobic composite of claim 1, characterized by beirg durable to dynamic water \ovear for at least 2 months.

   13. The hydrophobic composite of claim 1, wherein said hy=drophobic ‘powder is bonded to said core material via an adherent layer.

   14. Thee hydrophobic composite of claim 1, wherein said core material is selected from the _group consisting of a particulate material and a granulate material.

   15. Th_e hydrophobic composite of claim 1, wherein said core material is selected from time group consisting of sand, gravel, slag, porcelanit, dolomite, porcelain, basalt, quartz sand, coal ash, chalk, zeolite, montmorillonite, agapultite, flint, bentonite, —perlite, mica, wood chips, nut shells, sawdust and coembinations thereof.

   16. Thae hydrophobic composite of claim 14, wherein said core rmaterial has an average particle size ranging between 25 millimeters and 5 microns.

   17. Tie hydrophobic composite of claim 15, wherein said core= material is quartz sand. g 18. Thine hydrophobic composite of claim 13, wherein said adherent layer is a water-based adherent layer.

   19. Thhe hydrophobic composite of claim 18, wherein said water-based adherent layer comprises a water-based gluing agent.

   20. The hydrophobic composite of claim 13, wherein said adhesrent layer comprises a film-forming agent. : 21. The hydrophobic coxmposite of claim 20, wherein said filrm forming . agent is a film forming polyurethane=. © 22. The hydrophobic commposite of claim 20, wherein said adimerent layer } further comprises a gluing agent. " 23. The hydrophobic cormposite of claim 20, wherein said gluinag agent isa volatile hydrocarbon having at least: 12 carbon atoms.

   24. The hydrophobic composite of claim 23, wherein said gluing agent is selected from the group consisting of liquid asphalt, paraffin wax, beeswax, lanolin wax, linseed oil and combinations thereof. :

   25. The hydrophobic c-omposite of claim 22, wherein said sgluing agent constitutes between about 0.1 and sxbout 50 weight percentages of said adh_erent layer. : 26. The hydrophobic composite of claim 1, wherein said hydrophobic . powder further comprises hydrophobic fumed silica. . 27. The hydrophobic composite of claim 26, wherein said hydrophobic fumed silica constitutes between 1 and 99 weight percentages of said hydrophobic . powder,

   28. The hydrophobic composite of claim 13, wherein said a-dherent layer constitutes between about 0.5 arad about 7 weight percentages of the hydrophobic composite. }

   29. The hydrophobic composite of claim 1, wherein said hydrophobic powder constitutes between ab out 0.1 and about 5 weight percermtages of the hydrophobic composite. }

   34 i

   30. The hydrophobic composites of claim 26, wherein said hydrophobic powder constitutes between sbout 0.1 and about 5 weight percentages Of the hydrophobic composite.

   31. The hydrophobic composite of claim 1, further comprising at least one additive selected from the group consisting of a coloring agent, a UV resistant agent, a bleaching agent and an abrasive agent.

   32. The hydrophobic composites of claim 31, wherein said colorings agent constitutes between about 0.1 and about 2 weight percentages of the hydrogphobic . composite. : 33. The hydrophobic composite of claim 31, wherein said UV re=sistant agent and said bleaching agent each constit-utes between about 0.01 and about 2 —weight percentages of the hydrophobic composite.

   34. The hydrophobic composite of claim 31, wherein said abrasive agent constitutes between about 0.1 and about ©.5 weight percentages of the hydro phobic composite. :

   35. A method of preparing a hydrophobic composite, the rnethod comprising coating a core material with a hydrophobic powder, said hydro-phobic powder includes at least one impure elerment having a hydrocarbon chain attached thereto, to thereby provide the hydrophobic composite.

   36. The method of claim 35, further comprising, prior to said c=oating, - applying onto said core material an adherent layer, said adherent layer bondimg said hydrophobic powder to said core material.

   37. The method of claim 36, wherein said adherent layer comprises a film- forming agent and said step of applying onto said core material an adherermt layer comprises admixing said core material with an adherent mixture containing sai _d film- forming agent and a volatile solvent, whil« removing all of said volatile solvernit from

   85 ’ i the mixture of said core material and =said adherent mixture, to thereby provide said "core material having applied thereon said adherent layer.

   38. The method of claim 36, wherein said adherent layer comprises a . water-based gluing agent and said step of applying onto said core material an adherent layer comprises admixing said core material with an aqueous adherent mixture containing said water-based gluing ageent and an aqueous solvent, while removing all of said aqueous solvent from said mixture of said core material and said adherent mixture, to thereby provide said core= material having applied thereon said adherent layer.

   39. The method of claim 38, wherein a concentration of said water-based gluing agent in said aqueous adherent mixture ranges between about 1 weight percentage and about 99 weight percemtages.

   40. The method of claim 35, further comprising drying said core material prior to said coating. 41, The method of claims 35, further comprising drying said core material prior to said admixing.

   42. The method of claim 35, further comprising, after said coating, curing said hydrophobic composite. : 43. The method of claim 42, wherein said curing is performed for a time . period ranging between 1 and 30 days.

   44. The method of claim 37, wherein said removing said volatile solvent is performed by evaporative heating. 45, The method of claim 37, wherein said removing said volatile solvent is performed at room temperature.

   WYO 2005/005566 PCT/IL2004/000635

   46. The method of claim 37, wherein said volatile solvent is an organic solvent having a boiling temperature ranging between about 80 °C and 200 °C.

   47. The method of claim 38, wherein said aqueous solvent is water.

   48. The method of claim 38, wheredin removing said aqueous solwsent is performed by tumble drying. 49, The method of claim 35, further comprising, prior to said ceoating, admixing said core material with an additive selected from the group consistirag of a coloring agent, a UV resistant agent, a bleaching agent and an abrasive agent.

   50. The method of claim 37, further comprising, prior to said coating, admixing said core material having thereon said adherent layer with an additive selected from the group consisting of a coloering agent, a UV resistant agent, a bleaching agent and an abrasive agent.

   . 51. The method of claim 38, further comprising, prior to said Coating, admixing said core material having thereon =said adherent layer with an aadditive selected from the group comsisting of a coloring agent, a UV resistant a_gent, a bleaching agent and an abrasive agent. 52, The method of claim 35, whereira said core material is selected from the group consisting of a particulate material and a granulate material. 53, The method of claim 52, wherein said core material is selected £5rom the group consisting of sand, gravel, slag, porcelamit, dolomite, porcelain, basalt, quartz sand, coal ash, chalk, zeolite, montmorillonite, agapultite, flint, bentonite, perlite, “mica, wood chips, nut shells, sawdust and combinations thereof.

   54. The method of claim 52, wher ein said core material has an average particle size ranging between 25 millimeters aned 5 microns.

   55. The method of claim 53, wherein said core material is quartz sand.

   $6. The method of claim 37, wherein said film forming agent is a film forming polyurethane.

   57. The method of claim 37, wherein said emdherent mixture further comprises a gluing agent.

   58. The method of claim 57, wherein said gl ving agent is a volatile hydrocarbon having at least 12 carbon atoms.

   59. The method of claim 58, wherein said gluing agent is selected from the group consisting of liquid asphalt, paraffin wax, beeswax, lanolin wax, linseed oil and combinations thereof.

   60. The method of claim 35, wherein said hyc3rophobic powder has an average particle size ranging between 0.02 micron and 50 microns.

   61. The method of claim 35, wherein said hy=drophobic powder has a surface area ranging between 1 m?/gram and 60 m?¥ gram. : 62. The method of claim 35, wherein said hycirophobic powder further comprises hydrophobic fumed silica. : 63. The method of claim 62, wherein said Iaydrophobic fumed silica constitutes between 1 and 99 weight percentages of said hydrophobic powder.

   64. The method of claim 37, wherein said eadherent layer constitutes between about 0.5 and about 7 weight percentages of said hydrophobic composite.

   65. The method of claim 35, wherein said hydro-phobic powder constitutes between about 0.1 and about 5 weight percentages of said hydrophobic composite.

   66. A hydrophobic particulate comprising a particulated core mu aterial coated by a hydrophobic powder, said hydrophobic powder comprises at least one : impure element having a hydrocarbon. chain attached thereto.

   67. The hydrophobic particulate of claim 66, wherein said hydro carbon chain comprises at least 10 carbon atoms. :

   68. The hydrophobic particulate of claim 66, wherein said hydro carbon "chain is covalently attached to said at least one impure element.

   69. The hydrophobic parti culate of claim 68, wherein said hydrocart>on is a residue of a fatty acid having at least 12 carbon atoms.

   70. The hydrophobic particulate of claim 69, wherein said fatty acid is selected from the group consisting of stearic acid, lauric acid, myristic acid, palmitic acid, oleic acid, linolenic acid and arachidonic acid.

   71. The hydrophobic particulate of claim 66, wherein said at le ast one element is selected from the group consisting of a metallic element, a semi-Enetallic element, a transition metallic element and combinations thereof. : 72. The hydrophobic particulate of claim 66, wherein said at least one element is selected from the group consisting of magnesium, calcium, aluminumn, zinc,

   a . sodium, barium, zirconium, manganese, titanium, vanadium, chromium, ir~on and combinations thereof.

   73. The hydrophobic particulate of claim 66, wherein said hydreophobic powder has an average particle size ranging between 0.02 micron and 50 micros.

   74. The hydrophobic particulate of claim 66, wherein said hydreophobic "powder has a surface area ranging bestween 1 m*/gram and 60 m?*/gram, :

   75. The hydrophobic particulate of claim 66, characterized as being } inactive toward =alkaline reagents.

   76. The hydrophobic particulate of claim 66, being capeable of preventing water adherence thereto and water penetration therein under an exter—nal pressure of up to about 4.5 atmospheres. :

   77. “The hydrophobic particulate of claim 66, characterized by being durable to dynammic water wear for at least 2 months.

   . 78. ~The hydrophobic particulate of claim 66, wherein said hydrophobic powder is bondled to said particulated core material via an adherent Rayer.

   79. The hydrophobic particulate of claim 66, wherein sa id particulated core material is seslected from the group consisting of sand, gravel, slag, porcelanit, dolomite, porcelain, basalt, quartz sand, coal ash, chalk, zeolitee, montmorillonite, agapultite, flint, bentonite, perlite, mica, wood chips, nut shells, sawdust and combinations @hereof.

   80. The hydrophobic particulate of claim 66, wherein s=aid particulated core : material has am average particle size ranging between 25 millimeters and 5 microns.

   81. The hydrophobic particulate of claim 79, wherein saaid particulated core material is quartz sand.

   82. The hydrophobic particulate of claim 78, wherein s aid adherent layer is a water-based. adherent layer.

   83. The hydrophobic particulate of claim 82, where=in said water-based - adherent laye-r comprises a water-based gluing agent.

   84. The hydrophobic particulate of claim 78, whereira said adherent layer comprises a film-forming agent.

   ”

   85. The hydropEaobic particulate of claim 84, wherein said film forming agent is a film forming polyurethane.

   86. The hydrophobic particulate of claim 84, wherein said adherent layer "further comprises a gluing magent.

   87. The hydrophobic particulate of claim 84, wherein said gluing agent is a volatile hydrocarbon havin _g at least 12 carbon atoms.

   88. The hydrophobic particulate of claim 87, wherein said. gluing agent is selected from the group c-onsisting of liquid asphalt, paraffin wax, t>eeswax, lanolin : wax, linseed oil and combi nations thereof.

   89. The hydrophobic particulate of claim 86, wherein samid gluing agent Pp constitutes between about €.1 and about 50 weight percentages of said adherent layer.

   90. The hydrophobic particulate of claim 66, wherein seaid hydrophobic : powder further comprises Ihydrophobic fumed silica.

   91. The hydrophobic particulate of claim 90, wherein s=aid hydrophobic fumed silica constitutes beetween 1 and 99 weight percentages of saaid hydrophobic powder.

   92. The hydrophobic particulate of claim 78, wherein saied adherent layer constitutes between about 0.5 and about 7 weight percentages of athe hydrophobic particulate.

   93. The hydrophobic particulate of claim 66, wherein szaid hydrophobic powder constitutes betweeen about 0.1 and about 5 weight perscentages of the ; hydrophobic particulate.

   94. The hydrophobic particulate of claim 90, wherein said hydrophobic powder constitutes between about 0.1 and about 5 weight percentages of the hydrophobic particulate.

   95. The hydrophobic particulate of claim 66, further comprising at least one additive sel ected from the group consisting of a coloring agent, a UV resistant agent, a bleachirag agent and an abrasive agent.

   96. T he hydrophobic particulate of claim 95, wherein said coloring agent constitutes betw=een about 0.1 and about 2 weight percentages of thae bydrophobic particulate.

   97. T he hydrophobic particulate of claim 95, wherein said UV resistant : agent and said bleaching agent each constitutes between about 0.01 and about 2 weight percentages of tkhe hydrophobic particulate.

   98. The hydrophobic particulate of claim 95, wherein said abrasive agent constitutes between about 0.1 and about 0.5 weight percentages of tiaec hydrophobic particulate.

   99. Aa method of preparing a hydrophobic particulates, the method comprising coating a particulated core material with a hydrophobic powder, said hydrophobic po~wder comprises at least one impure element having a hydrocarbon chain attached thereto, to thereby provide the hydrophobic particulate.

   100. The method of claim 99, further comprising, prior to said coating, applying onto saaid particulated core material an adherent layer, said adherent layer bonding said hyc3rophobic powder to said particulated core material.

   101. The method of claim 100, wherein said adherent layer comprises a film-forming ageent and said step of applying onto said particulated core material an adherent layer comprises admixing said particulated core material with an adherent mixture containing said film-forming agent and a volatile solvent, whille removing all

   ~ 92 } ] of said volatile solvent from the mixture of said particulated core materiaal and said adherent mixture, to thereby provide said particulated core material havisng applied thereon said adherent layer.

   102. The method of claim 36, wherein said adherent layer comprises a water-based gluing agent and said step of applying onto said core material Zan adherent layer comprises admixing said core material with an aqueous adhere=nt mixture containing said water-based gluing agent and an aqueous solvent, while removing all of said aqueous solvent fromm the mixture of said core material and sa_id aqueous adherent mixture, to thereby provide said core material having applied thereon said adherent layer.

   103. The method o f claim 102, wherein a concentration of said water-based gluing agent in said adheren_t mixture ranges between about 1 weight perscentage and about 99 weight percentages

   104. The method ©f claim 99, further comprising drying said particulated core material prior to said co ating.

   105. The method of claim 101, further comprising drying said particulated core material prior to said admixing.

   106. The method Of claim 99, further comprising, after said coating, curing said hydrophobic particulates.

   107. The method ef claim 106, wherein said curing is performed for a time * period ranging between 1 amd 30 days.

   108. The method of claim 101, wherein said removing of said volatile solvent is performed by evaporative heating.

   109. The method of claim 101, wherein said removing of said volatile solvent is performed at roorm temperature.

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   110. The method of claim 101, wheresin said volatile solvent is an organic solvent having a boiling temperature ranging bet-ween about 80 °C and 200 °C.

   111. The method of claim 102, whereim said aqueous solvent is water.

   112. The method of claim 102, wherein said removing of said water is performed by tumble drying.

   113. The method of claim 99, further comprising, prior to said coating, admixing said particulated core material witlm an additive selected from the gZroup consisting of a coloring agent, a UV resistant a gent, a bleaching agent and an abraasive agent. ‘ }

   114. The method of claim 101, further comprising, prior to said cosating, admixing said particulated core material having thereon said adherent layer wi th an

   . additive selected from the group consisting of a coloring agent, a UV resistant ag ent, a bleaching agent and an abrasive agent.

   115. The method of claim 99, wherein said particulated core material is selected from the group consisting of sarad, gravel, slag, porcelanit, dolOmite, - porcelain, basalt, quartz sand, coal ash, chalk, zeolite, montmorillonite, agapwultite, flint, bentonite, perlite, mica, wood chips, mut shells, sawdust and combin ations thereof.

   116. The method of claim 99, wherein said particulated core material has an average particle size ranging between 25 milliameters and 5 microns.

   117. The method of claim 115, wkaerein said particulated core material is quartz sand.

   118. The method of claim 101, wherein said film forming agent is a film forming polyurethane.

   1719. The method of claim 101, wherein said adherent mixture further comprise=s a gluing agent. 1 20. The method of claim 119, wherein said gluing agent is a volatile hydrocarbon having at least 12 carbon atoms.

   1.21. The method of claim 120, wherein said gluing agent is selected from the group consisting of liquid asphalt, paraffin wax, Eeeswax, lanolin wax, linseed oil and commbinations thereof. ®722. The method of claim 99, wherein s-aid hydrophobic powder has an average particle size ranging between 0.02 micron an-d 50 microns. —123. The method of claim 99, wherein said hydrophobic powder has a surface area ranging between 1 m?/gram and 60 m%/g-ram.

   124. Thc method of claim 99, wherein said hydrophobic powder further comprisses hydrophobic fumed silica. : 125. The method of claim 124, whereira said hydrophobic fumed silica constit_ates between 1 and 99 weight percentages of ssaid hydrophobic powder.

   126. The method of claim 101, whereir said adherent layer constitutes betwee=n about 0.5 and about 7 weight percentages of said hydrophobic particulate.

   127. The method of claim 99, wherein saiid hydrophobic powder constitutes betwee=n about 0.1 and about S weight percentages o f said hydrophobic particulate.

   128. A free-flowing hydrophobic aggregate capable of repealing a predete=rmined maximal pressure of liquid, the free-flowing hydrophobic aggregate comprising a plurality of differently sized particulzates, wherein at least one of a size distribmution of said particulates, a contact angle between the liquid and said particulates and a characteristic distance between aadjacent particulates is selected so that when a layer of the free-flowing hydrophobic aggregate is in contact with a liquid having a pressure lower than or equal to the predetermined maximal pressures, percolation of the liquid through the free-flowing hydrophobic aggregate is prevented. ) 129. The free-flowing hydrophobic aggregate of claim 123, wherein the liquid is water.

   130. The free-flowing hydrophobic aggregate of claim 128, wherein said layer has a thickness from about 1 cm to about 10cm and further wherein thme predetermined maximal pressure is equivalent to a column of water having a height above 30 cm.

   131. The free-flowing hydrophobic aggregate of claim 128, wherein said layer has a thickness from about 1cm to about 10cm and further wherein the predetermined maximal pressure is equivalent to a column of water having a heighht above 100 cm.

   132. The free-flowing hydrophobic aggregate of claim 128, wherein said size distribution is characterized by a variance ranging from 1 micrometer to 1400 micrometer,

   133. The free-flowing hydrophobic aggregate of claim 128, wherein sazid : size distribution is selected so that a maximal diameter of capillaries formed between oo said particulates is suitable for repealing the predetermined maximal pressure of the liquid.

   134. The free-flowing hydrophobic aggregate of claim 128, wherein sa-id size distribution is selected so that a maximal diameter of capillaries formed between said particulates is from 1 nanometer to SO0 nanometers.

   135. The free-flowing hydrophobic aggregate of claim 128, furth er comprising inflatable particulates size wise compatible with capillaries formesd between said particulates and capable of absorbing the liquid.

   136. The free-flowing hydrophobic aggregate of claim 135, wherein an absorption capability of said inflat-able particulates is from about 100 to about 5000 by weight.

   137. The free-flowing hydrophobic aggregate of claim 135, wherein a freezing temperature of said inflatable particulates below about -20 degrees _ centigrade, both in an inflated state and in a deflated state of said inflatable "particulates.

   138. The free-flowing Faydrophobic aggregate of claim 135, wherein said inflatable particulates, when in a deflated state, constitute less than 2 percent of the } free-flowing hydrophobic aggregate by volume.

   139. The free-flowing hydrophobic aggregate of claim 135, wherein a diameter of said inflatable particulates is from about 1 micrometer to about 1000 micrometers.

   140. The free-flowing hydrophobic aggregate of claim 135, wherein said inflatable particulates comprise a ssuper absorbent polymer.

   141. The free-flowing hhydrophobic aggregate of claim 135, wherein said inflatable particulates comprises s-odium being cross linked with polyacrylic acid.

   142. The free-flowing Mhydrophobic aggregate of claim 135, wherein said inflatable particulates comprises a nti-caking agent.

   143. The free-flowing hydrophobic aggregate of claim 128, wherein said size distribution is selected so that the free-flowing hydrophobic aggregate is characterized by a predetermined sspecific weight. -

   144. The free-flowing hydrophobic aggregate of claim 128, wherein said size distribution is selected so that the free-flowing hydrophobic aggregate is characterized by a minimal water absorption capability.

   145. The free-flowing hydrophobic aggregate of claim 128, wherein said size distribution is selected so that the free-—flowing hydrophobic aggregate is " characteriz=ed by predetermined thermal properties . 1465. The free-flowing hydrophobic agmeregate of claim 145, wherein said predetermined thermal properties are selected freom the group consisting of thermal conductivity, specific heat capacity and latent heat. :

   147. The free-flowing hydrophobic aggregate of claim 128, wherein said size distribution is selected so that the free—flowing hydrophobic aggregate is characterized by predetermined acoustical isolaticomn ability. 14-8. The free-flowing hydrophobic aggregate of claim 128, wherein said size distri bution is selected so that the free-flowi_ng hydrophobic aggregate is capable of allowirg evaporation of the liquid. 1489. The free-flowing hydrophobic agzgregate of claim 128, wherein said size distri_bution is proportional to the predetermimned maximal pressure.

   150. The free-flowing hydrophobic aggeregate of claim 128, wherein a cosine of said contact angle is proportional to the predetermined maximal pressure, said contact angle is measured from a tangent to a surface defined by the free-flowing hydrophosbic aggregate. oo 1551. The free-flowing hydrophobic aggregate of claim 128, wherein said . characterdistic distance is inversely proportiomnal to the predetermined maximal pressure. 1552. The free-flowing hydrophobic aggregate of claim 128, wherein said plurality of differently sized particulates comprisses a particulated core material coated by a hydr—ophobic material selected so as to provide said contact angle.

   153. The free-flowing hyzdrophobic aggregate of claim 152, wherein said hydrophobic material is a hydrophobic powder.

   154. The free-flowing hydrophobic aggregate of claim 153, wherein said hydrophobic powder comprises at- least one impure element having a hydrocarbon chain attached thereto.

   155. The free-flowing hydrophobic aggregate of claim 154, wherein said hydrocarbon chain is covalently attached to said at least one impure element.

   156. The free-flowing Imydrophobic aggregate of claim 155, wherein said hydrocarbon is a residue of a fatty acid.

   157. The free-flowing Inydrophobic aggregate of claim 152, wherein said hydrophobic material is bonded to said particulated core material via an adherent layer.

   158. The free-flowing Thydrophobic aggregate of claim 152, wherein saidl hydrophobic powder comprises iraflatable particulates capable of absorbing the liquid.

   159. The free-flowing hydrophobic aggregate of claim 158, wherein a diameter of said inflatable particulates is from about 1 micrometer to about 100 micrometers.

   160. The free-flowing hydrophobic aggregate of claim 158, wherein amn absorption capability of said inflatable particulates is from about 100 to about 5000 by weight. oo 161. The free-flowing: hydrophobic aggregate of claim 158, wherein a freezing temperature of said inflatable particulates is below about -20 degree=s ‘ © centigrade, both in an inflateed state and in a deflated state of said inflatable particulates.

   162. The free-flowing hydrophobic aggregate off claim 158, wherein said inflatable particulates, when in a deflated state, constitute less than 1 percent of the free-flowimg hydrophobic aggregate by volume.

   163. The free-flowing hydrophobic aggregate of claim 158, wherein said : inflatable particulates comprise a super absorbent polymer.

   164. The free-flowing hydrophobic aggregate of claim 158, wherein said inflatable particulates comprises sodium being cross linked with polyacrylic acid.

   165. The free-flowing hydrophobic aggregate o»f claim 158, wherein said inflatable particulates comprises anti-caking agent.

   166. The free-flowing hydrophobic aggregate of claim 152, wherein said particulated core material is selected from the group consisting of sand, gravel, slag, porcelanit, dolomite, porcelain, basalt, quartz sand, coal ash, chalk, zeolite, montmor-illonite, agapultite, flint, bentonite, perlite, mica, wood chips, nut shells, sawdust zand combinations thereof. Lo 1657. The free-flowing hydrophobic aggregate of claim 157, wherein said adherent layer is a water-based adherent layer.

   168. The free-flowing hydrophobic aggregate eof claim 167, wherein said water-based adherent layer comprises a water-based gluing agent.

   169. The free-flowing hydrophobic aggregate «of claim 157, wherein said adherent layer comprises a film-forming agent. 1-70. The free-flowing hydrophobic aggregate -of claim 169, wherein said adherent layer further comprises a gluing agent.

   171. The free-flowing hydrophobic aggregate of claim 152, wherein said hydrophobic powder further comprises hydrophobic fumed silica.

   172. The free-flowing hydrophobic aggregate of clmaim 152, further comp ising at least one additive selected from the group consisting cf a coloring agent, aUV resistant agent, a bleaching agent and an abrasive agent.

   173. A hydrophobic brick comprising a protective encampsulation having a predetermined shape, and a free-flowing hydrophobic aggregate be=ing encapsulated in . said gprotective encapsulation. RE 174. The hydrophobic brick of claim 173, wheredin said protective encapsulation is made from a degradable material.

   175. The hydrophobic brick of claim 173, wherein said free-flowing hydrophobic aggregate comprises a plurality of differently size=d particulates, and further wherein at least one of a size distribution of said particulates, a contact angle . between a liquid and said particulates and a characteristic distanece between adjacent particulates is selected so that when the free-flowing hydrophobic aggregate is in contact with a liquid having a pressure lower than or equal to a predetermined maximal pressure, percolation of the liquid through the free-flowing hydrophobic aggmegate is prevented.

   176. The hydrophobic brick of claim 175, wherein saied size distribution is sele=cted so that a maximal diameter of capillaries formed between said particulates is . . suit able for repealing the liquid.

   177. The hydrophobic brick of claim 175, further comprising inflatable s particulates size wise compatible with capillaries formed between. said particulates and cap able of absorbing the liquid.

   178. The hydrophobic brick of claim 177, whezrein said inflatable particulates, when in a deflated state, constitute less than 2 percemnt of the free-flowing hydrophobic aggregate by volume. }

   179. Th. e hydrophobic brick of claim 177, wwherein said inflatable particulates comp-Tise a super absorbent polymer.

   180. Time hydrophobic brick of claim 177, —wherein said inflatable particulates compsrises sodium being cross linked with polyacrylic acid.

   181. Thue hydrophobic brick of claim 177, wherein said inflatable particulates comprises anti-caking agent.

   182. The hydrophobic brick of claim 175, wherein said size distribution is selected so tha® the free-flowing hydrophobic aggregate is characterized by a predetermined specific weight. E 183. Thhe hydrophobic brick of claim 175, wherein said size distribution is selected so that the free-flowing hydrophobic aggregate is cTharacterized by a minimal "absorption capabwility.

   184. The hydrophobic brick of claim 175, wherefin said size distribution is "selected so theat the free-flowing hydrophobic aggregsate is characterized by predetermined tlaermal properties.

   185. The hydrophobic brick of claim 175, wheredin said size distribution is selected so thaat the free-flowing hydrophobic aggregeate is characterized by predetermined aecoustical isolation ability.

   186. The hydrophobic brick of claim 175, wherein said size distribution is "selected so tha-t the free-flowing hydrophobic aggregate is capable of allowing evaporation of 1 quid. :

   187. The hydrophobic brick of claim 173, wherein said free-flowing hydrophobic aggregate comprises a articulated core materizal coated by a hydrophobic material.

   188. The hydrophobic brick of claim 187, wheredin hydrophobic material is a hydrophobic powder.

   189. The hydrophobic brick of claim 188, where=in said hydrophobic powder comprises at Meast one impure element having a hydrocarbon chain attached thereto. : 190. The hydrophobic brick of claim 189, wherein said hydrocarbon chain is covalently attached to said at least one impure element.

   191. The hydrophobic brick of claim 190, wimerein said hydrocarbon is a residue of a £atty acid.

   192. The hydrophobic brick of claim 187, wherein said hydrophobic

   . material is bonded to said particulated core material via ar adherent layer. ’ 193. The hydrophobic brick of claim 187, wherein said hydrophobic powder comprises iraflatable particulates capable of absorbing 1-5iquid when being in contact therewith.

   194. The hydrophobic brick of claim 193, wherein said inflatable particulates, when in a deflated state, constitute less than 2 percent of the free-flowing ‘hydrophobic= aggregate by volume.

   195. The hydrophobic brick of claim 193, wherein said inflatable particulates ecomprise a super absorbent polymer.

   196. The hydrophobic brick of claim 19 3, wherein said inflatable particulates acomprises sodium being cross linked with polyacrylic acid.

   197. The hydrophobic brick of claim 19%3, wherein said inflatable

   . particulates «Comprises anti-caking agent.

   198. The hydrophobic brick of claim 1-87, wherein said particulated core mater—ial is selected from the group consisting of sand, gravel, slag, porcelanit, dolomite, porcelain, basalt, quartz sand, coal assh, chalk, zeolite, montmorillonite, agapualtite, flint, bentonite, perlite, mica, woocl chips, nut shells, sawdust and combinations thereof.

   199. The hydrophobic brick of claim 192, wherein said adherent layer is a watemr-based adherent layer. :

   200. The hydrophobic brick of claim 199, wherein said water-based adherent layer= comprises a water-based gluing agent.

   201. The hydrophobic brick of claim 192, wherein said adherent layer comprises a film-forming agent.

   202. The hydrophobic brick of claim 201, wherein said adherent layer © furtlqer comprises a gluing agent.

   203. The hydrophobic brick of claim 187, wherein said hydrophobic powder furtbher comprises hydrophobic fumed silica. s 204, The hydrophobic brick of claimn 187, wherein said free-flowing hydrophobic aggregate further comprises at least one additive selected from the group conssisting of a coloring agent, a UV resistant agent, a bleaching agent and an abrasive agemnt.

   205. A method of waterproofing a po-rtion of a structure being in contact witha a ground, comprising: providing a bed of a free-flowing hydroplnobic aggregate; and positioning said structure over or in said “bed of said free-flowing hydrophobic aggregate,

   206. The method of claim 205, further czomprising protecting said be d of free-flowing h_ydrophobic aggregate by enclosing said bed in a protective structure-.

   207. The method of claim 205, wherein said bed of said free-flo-wing . hydrophobic aggregate comprises an arrangement o f hydrophobic bricks, each being a protective enecapsulation having a predetermined sshape and encapsulating said free N flowing hydrophobic aggregate.

   208. The method of claim 207, whereim said protective encapsulati on is " madefroma degradable material.

   209. The method of claim 205, whereim a thickness of said bed of” free- flowing hydr-ophobic aggregate is between 1 and 15S cm.

   210. The method of claim 205, wherein a thickness of said bed of free- flowing hydrophobic aggregate is between 4 and 190 cm.

   211. The method of claim 205, further comprising mixing said free-fl owing hydrophobic aggregate with lightweight aggregatess.

   912. The method of claim 205, wherein said free-flowing hydrosphobic : aggregate comprises a plurality of differently sized particulates, and further wherein at : least one of a size distribution of said particulates, a contact angle between a liquaid and said particulates and a characteristic distance betveveen adjacent particulates is se€lected so that whemn the free-flowing hydrophobic aggreg=ate is in contact with a liquid having a pressure lower than or equal to a predetermined maximal pressure, percolatior of the ’ liquid throu gh the free-flowing hydrophobic aggregate is prevented. : 213_ The method of claim 212, wherein said liquid is water. 214_ The method of claim 212, whereimn said size distribution is selected so that a maximal diameter of capillaries formed be=tween said particulates is suit=able for repealing tie liquid.

   2715. The method of claim 212, further comperising inflatable particulates size wise cormpatible with capillaries formed between s aid particulates and capable of absorbingg the fluid. 2 16. The method of claim 215, wherein sai-d inflatable particulates, when in a deflateed state, constitute less than 2 percent of the free-flowing hydrophobic aggregate by volume.

   17. The method of claim 215, wherein sai_d inflatable particulates comprise a super aabsorbent polymer.

   18. The method of claim 215, wherein said inflatable particulates : comprisses sodium being cross linked with polyacryliec acid.

   319. The method of claim 215, wherein said inflatable particulates comprises anti-caking agent.

   220. The method of claim 212, wherein s=aid size distribution is selected so that thee free-flowing hydrophobic aggregate is characterized by a predetermined specific weight. :

   221. The method of claim 212, wherein ssaid size distribution is selected so that thes free-flowing hydrophobic aggregate is characterized by a minimal absorption capability.

   222. The method of claim 212, wherein ssaid size distribution is selected so that the= free-flowing hydrophobic aggregate is characterized by predetermined thermal oo properties.

   223. The method of claim 212, wherein =said size distribution is selected so that the free-flowing hydrophobic aggregate iss characterized by predetermined acoustical isolation ability.

   224. The method of claim 212, wherein said size distribution is selected so that the free-flowing hydrophobic aggregate is capable of allowing evaporation of liquid. ~

   225. The method of claim 205, wherein said free-flowing hydrophobic aggregate comprises a particulated core material coated by a hydrophobic material.

   926. The method of claim 225, wherein said hydrophobic material is a hydrophobic powder.

   227. The method of claim 226, wherein said hydrophobic powder cormprises atleast one impure element having a hydrocarbon chain attached thereto.

   228. The method of claim 227, wherein said hydrocarbon chain is covalently attached to said at least one impure element.

   229. The method of claim 228, wherein said hydrocarbon is a residue of a fatty acid. ’ 230. The method of claim 227, wherein said hydrophobic powder is Tbonded to said particulated core material via an adherent layer. - 231. The method of claim 227, wherein said hydrophobic powder cormprises inflatable particulates capable of absorbing fluid when being in contact therewith.

   232. The method of claim 231, wherein said inflatable particulates, vwhen in . a deflated state, constitute less than 2 percent of the free-flowing hydrosphobic aggregate by volume. ’ 233. The method of claim 231, wherein said inflatable particulates comprise a super absorbent polymer.

   234. The -method of claim 231, wherein said inflatable particulates comprises sodium be=ing cross linked with polyacrylic acid.

   235. The method of claim 231, wherein said inflatable particumlates comprises anti-cakirmg agent.

   236. The method of claim 226, wherein said particulated core material is selected from the group consisting of sand, gravel, slag, porcelanit, dolosmite, porcelain, basalt, quartz sand, coal ash, chalk, zeolite, montmorillonite, agapwltite, flint, bentonite, perlite, mica, wood chips, nut shells, sawdust and combinations thereof.

   237. The -method of claim 230, wherein said adherent layer is a water—based adherent layer.

   238. The method of claim 237, wherein said water-based adherent layer comprises a water-based gluing agent.

   239. The method of claim 230, wherein said adherent layer comprises a film-forming agent . -

   240. The method of claim 239, wherein said adherent layer Further comprises a gluing agent.

   241. The method of claim 227, wherein said hydrophobic powder —further comprises hydrophmobic fumed silica.

   242. The= method of claim 226, wherein said free-flowing hydro—phobic aggregate further ccomprises at least one additive selected from the group consissting of a coloring agent, a UV resistant agent, a bleaching agent and an abrasive agent.

   243. A method of waterproofing an uanderground wall of a structwure, comprising providing at least one sidewall of a fizee-flowing hydrophobic aggressate adjacent to the underground wall of the structure.

   244. The method of claim 243, further comprising protecting said side=wall of free-flowing hydrophobic aggregate by enclo sing said sidewall in a protective straacture.

   245. The method of claim 243, further ccomprising refilling said sidewall of free-flowing hydrophobic aggregate, with time.

   246. The method of claim 243, whereim said sidewall of said free-flo—wing hy~drophobic aggregate comprises an arrangement of hydrophobic bricks, each be-ing a : protective encapsulation having a predetermined . shape and encapsulating said free- flowing hydrophobic aggregate.

   247. The method of claim 246, whereein said protective encapsulati on is made from a degradable material.

   248. The method of claim 243, further acomprising coating said underground wall of said structure with a waterproofing =substance selected from the _group consisting of a liquid and a paste.

   249. The method of claim 243, whereir the structure is an existing strumcture, amd said method is applied as a repair method.

   250. The method of claim 243, whereimn the structure is a new structur—e, and said method is applied during construction.

   251. The method of claim 243, wheerein said free-flowing hydrogphobic aggregate comprises a plurality of differently siz=ed particulates, and further whesrein at least one of a size distribution of said particulatess, a contact angle between a liquid and s aid particulates and a characteristic distance be~tween adjacent particulates is se=lected

   .. so that when the free— flowing hydrophobic aggregate is in contact with 2a liquid having .- a pressure lower than or equal to a predetermined maximal pressure, per—colation of the liquid through the fre-e-flowing hydrophobic aggregate is prevented. 1252. The mmethod of claim 251, wherein said liquid is water.

   253. The method of claim 251, wherein said size distributiomn is selected so that a maximal diam_eter of capillaries formed between said particulate=s is suitable for repealing the liquid.

   254. The method of claim 251, further comprising inflatable —particulates size wise compatible wilith capillaries formed between said particulates and capable of absorbing the fluid.

   255. The mmethod of claim 254, wherein said inflatable parti-culates, when in a deflated state, c-onstitute less than 2 percent of the free-flowing hydrophobic - aggregate by volum_e.

   256. The —method of claim 254, wherein said inflatable parti- culates comprise . asuper absorbent peolymer.

   257. The method of claim 254, wherein said inflateable particulates comprises sodium boeing cross linked with polyacrylic acid.

   258. The method of claim 254, wherein said inflatable particulates comprises anti-cakiing agent.

   259. The= method of claim 251, wherein said size distribut=ion is selected so that the free-flow—ing hydrophobic aggregate is characterized by a predetermined specific weight.

   260. The mesthod of claim 251, wherein said size distribution is selected so that the free-flowing hydrophobic aggregate is characterized by a minimal absorption capability.

   261. The meethod of claim 251, wherein said size distrilbution is selected so that the free-flowing Inydrophobic aggregate is characterized by predetermined thermal properties.

   262. The method of claim 251, wherein said size distri_bution is selected so that the free-flowing hydrophobic aggregate is characterizecld by predetermined acoustical isolation allbility.

   263. The method of claim 251, wherein said size distribution is selected so that the free-flowing hydrophobic aggregate is capable of alloswing evaporation of liquid. : 264. The mmethod of claim 243, wherein said free-flowing hydrophobic aggregate compriscs a particulated core material coated by a hydrophobic material.

   265. The mmethod of claim 264, wherein said hydrosphobic material is a

   . hydrophobic powder.

   266. The rmethod of claim 265, wherein said hydropho=bic powder comprises at least one impure element having a hydrocarbon chain attached_ thereto.

   267. The method of claim 266, wherein said hydrocart>on chain is covalently attached to said at least one impure element.

   268. The -method of claim 267, wherein said hydrocamrbon is a residue of a fatty acid.

   269. The -method of claim 266, wherein said hydropheobic powder is bonded to said particulated core material via an adherent layer.

   nm 2-70. The method of claim 266, wherein said hydrophobic powder comprises inflatables particulates capable of absorbing fluid when being in contact therewith. 2-71. The method of claim 270, wherein said inflatable particulates, when in a deflatexd state, constitute less than 2 percent of the free-flowing hydrophobic aggregates by volume. : 2-72. The method of claim 270, wherein said inflamtable particulates comprise a super absorbent polymer. 2-73. The method of claim 270, wherein said inflatable particulates comprise=s sodium being cross linked with polyacrylic acid. 2-74. The method of claim 270, wherein saaid inflatable particulates comprise=s anti-caking agent. 2=75. The method of claim 265, wherein said pamrticulated core material is selected from the group consisting of sand, gravel, slag, porcelanit, dolomite, porcelainm, basalt, quartz. sand, coal ash, chalk, zeolite, montmorillonite, agapultite, flint, beratonite, perlite, mica, wood chips, nut shells, sawdust and combinations thereof. 2776. The method of claim 269, wherein said adhesrent layer is a water-based adherent “layer. : 2777. The method of claim 276, wherein said water-based adherent layer comprises=s a water-based gluing agent. 2778. The method of claim 269, wherein said aclherent layer comprises a film-fornming agent.

   279. The method of claim 278, wherein sail adherent layer further comprises a gluing agent.

   oo WO 20057005566 PCT/IL2004/000635 2630. The method of claim 266, wherein =said hydrophobic powder further comprise=s hydrophobic fumed silica. 2:81. The method of claim 265, whereim said free-flowing hydrophobic aggregatee further comprises at least one additive selected from the group consisting of a colorin_g agent, a UV resistant agent, a bleaching agzent and an abrasive agent. - 2282. A method of waterproofing a floor o=f a structure, comprising providing a bed of a free-flowing hydrophobic aggregate onto said structure and positioning the floor of the structure over said bed of said free-flowing hydrophobic aggregate.

   283. The method of claim 282, wherein a_ thickness of said bed of said free- flowing hydrophobic aggregate is between 1 and 15 om. ’ 84. The method of claim 282, wherein za thickness of said bed of said free- flowing : hydrophobic aggregate is between 4 and 7 «cm.

   —35. The method of claim 282, further comprising protecting said bed of said free-flowing hydrophobic aggregate by en closing said bed in a protective structur-e.

   286. The method of claim 282, wherein said bed of said free-flowing hydrophobic aggregate comprises an arrangement «of hydrophobic bricks, each being a protective encapsulation having a predetermined shape and encapsulating said free- flowing hydrophobic aggregate. . 287. The method of claim 286, wherein said protective encapsulation is made from a degradable material.

   288. The method of claim 282, further comprising embedding a pipe in said bed of said free-flowing hydrophobic aggregate.

   WED) 2005/005566 PCT/IL20 04/000635 : 289. The method of claim 282, further comprising mixing said free—flowing hy=drophobic aggregate with lightweight aggregat-es.

   200. The method of claim 282, wherein said free-flowing hyd=rophobic aggregate comprises a plurality of differently sizzed particulates, and further w=herein at le=ast one of a size distribution of said particulates, a contact angle between a 15 quid and said particulates and a characteristic distance bestween adjacent particulates iss selected se that when the free-flowing hydrophobic aggresgate is in contact with a liquid having a pressure lower than or equal to a predetermine=d maximal pressure, percolat—ion of the IR quid through the free-flowing hydrophobic aggregate is prevented.

   201. The method of claim 290, wherein said liquid is water.

   292. The method of claim 290, wher ein said size distribution is s=elected so that a maximal diameter of capillaries formed between said particulates is suitable for mepealing the liquid.

   203. The method of claim 290, furthesr comprising inflatable particulates size —wise compatible with capillaries formed between said particulates and ecapable of —absorbing the fluid.

   204. The method of claim 293, wherein said inflatable particulates, when in a deflated state, constitute less than 2 percent of the free-flowing hydrophobic aggregate by volume.

   295. The method of claim 293, whenrein said inflatable particulates comprise a super absorbent polymer.

   296. The method of claim 293, wherein said inflatable particulates comprises sodium being cross linked with polyacrylic acid.

   207. The method of claim 293. wherein said inflatable particulates comprises anti-caking agent.

   298. The method of claim 290, wherein said size distribution is selected so that the free-flowing hydrophobic aggregate is characterized by a predetermined specific weight.

   299. The method of claim 290, wherein said size distribution is selected so that the free-flowing hydrophobic aggregate is characterized by a minimal absorption capability.

   300. The method of claim 290, wherein said size distribution is selected so that the free-flowing hydrophobic aggregate is characterized by predetermined thermal properties.

   301. The method of claim 290, wherein said size distribution is selected so that the free-flowing hydrophobic aggregate is characterized by predetermined acoustical isolation ability.

   302. The method of claim 290, wherein said size distribution is selected so that the free-flowing hydrophobic aggregate is capable of allowing evaporation of liquid. } 303. The method of claim 282, wherein said free-flowing hydrophobic aggregate comprises a particulated core material coated by a hydrophobic material.

   304. The method of claim 303, wherein said hydrophobic material is a hydrophobic powder.

   305. The method of claim 304, wherein said hydrophobic powder comprises at least one impure element having a hydrocarbon chain attached thereto. . 306. The method of claim 305, wherein said hydrocarbon chain is covalently attached to said at least one impure element. :

   307. The method of claim 306, wherein said hydrocarbon is a residue of a fatty acid.

   308. The method of claim 3 05, wherein said hydrophobic powder is bomded #0 said particulated core material via an adherent layer. . 309. The method of claim 3 05, wherein said hydrophobic powder comprises "inflatable particulates capable of absoxbing fluid when being in contact therewith. - 310. The method of claim 309, wherein said inflatable particulates, whnen in © a deflated state, constitute less than 2 percent of the free-flowing hydrophobic aggregate by volume,

   311. The method of claim 309, wherein said inflatable particulates conaprise a super absorbent polymer.

   312. The method of claim 309, wherein said inflatable particulates comprises sodium being cross linked with polyacrylic acid.

   313. The method of claim 309, wherein said inflatable particulates comprises anti-caking agent.

   314. The method of claim 304, wherein said particulated core matemrial is selected from the group consisting of sand, gravel, slag, porcelanit, dolomite, porcelain, basalt, quartz sand, coal ash, chalk, zeolite, montmorillonite, agap-ultite, flint, bentonite, perlite, mica, wood chips, nut shells, sawdust and combin_ ations thereof.

   315. The method of claim 308, wherein said adherent layer is a water—based adherent layer.

   316. The method of claim 315, wherein said water-based adherent layer comprises a water-based gluing agen t.

   317. The method of claim 308, wherein said adherent layer © omprises a film-formingy agent.

   318. The method of claim 317, wherein said adherent laZyer further comprises a gluing agent.

   319. The method of claim 304, wherein said hydrophobic povevder further comprises hydrophobic fumed silica.

   320. The method of claim 304, wherein said free-flowing hydrophobic aggregate farther comprises at least one additive selected from the group consisting of a coloring a gent, a UV resistant agent, a bleaching agent and an gbrasive agzent. 321_ A method of waterproofing a roof of a structure, the oof having sidewalls, the method comprising: applying a bed of a free-flowing hydrophobic aggregate on said roo=f; and covering said bed of said free-flowing hydrophobic aggregate, to protect said bed. : 322_ The method of claim 321, wherein said covering comprise-s applying a floor over said bed of said free-flowing hydrophobic aggregate. 323 . The method of claim 321, wherein said bed of said free-flowing hydrophob® c aggregate comprises an arrangement of hydrophobic bricks, «each being a ) protective encapsulation having a predetermined shape and encapsulating said free- flowing hy<lrophobic aggregate. 324-. The method of claim 323, wherein said protective encapsulation is made from a degradable material. ; 325. The method of claim 321, wherein a thickness of said bed of said free- flowing hyedrophobic aggregate is between 1 and 15 cm.

   326. The method of claim 321, wherein a thicknesss of said bed of said free- flowing hydrophobic aggregate is between 4 and 7 cm.

   327. The method of claim 321, further comprisinzg mixing said free-flowing hydrophobic aggregate with lightweight aggregates.

   328. The method of claim 321, wherein said free-flowing hydrophobic aggregate comprises a plurality of differently sized particul ates, and further wherein at least one of ea size distribution of said particulates, a contact= angle between a liquid and said particulates and a characteristic distance between adjacent particulates is selected so that wher the free-flowing hydrophobic aggregate is in contact with a liquid having a pressure lowwer than or equal to a predetermined maximal pressure, percolation of the liquid througzh the free-flowing hydrophobic aggregate is pmrevented.

   LL. 329. The method of claim 328, wherein said liquaid is water.

   330. The method of claim 328, wherein said siz=e distribution is selected so that a maxirmnal diameter of capillaries formed between said particulates is suitable for repealing th e liquid.

   331. The method of claim 328, further comprisimg inflatable particulates size wise compatible with capillaries formed between said particulates and capable of absorbing the fluid. 332 The method of claim 331, wherein said in#flatable particulates, when in a deflated state, constitute less than 2 percent of thee free-flowing hydrophobic aggregate bey volume.

   333. The method of claim 331, wherein said in#flatable particulates comprise a super abs-orbent polymer.

   334.. The method of claim 331, wherein said inflatable particulates comprises sodium being cross linked with polyacrylic acied.

   335. The method of claimm 331, wherein said inflatable particulates : comprises anti-caking agent.

   . 336. The method of claim 328, wherein said size distribution is selected s=0 that the free-flowing hydrophobic aggregate is characterized by a predetermine -d specific weight. "337. The method of claim 3728, wherein said size distribution is selected S50 that the free-flowing hydrophobic aggregate is characterized by a minimal absorption capability.

   338. The method of claim 3 28, wherein said size distribution is selected =s0 that the free-flowing hydrophobic aggregate is characterized by predetermined thernmal properties. :

   330. The method of claim 28, wherein said size distribution is selected so

   . that the free-flowing hydrophobic aggregate is characterized by predetermin_ed "acoustical isolation ability.

   340. The method of claim 328, wherein said size distribution is selected so that the free-flowing hydrophobic azggregate is capable of allowing evaporation of liquid.

   341. The method of claim 321, wherein said free-flowing hydrophobic aggregate comprises a particulated co re material coated by a hydrophobic material.

   342. The method of claim 341, wherein said hydrophobic material iss a hydrophobic powder.

   343. The method of claim 342, wherein said hydrophobic powder comprises at least one impure element having a hydrocarbon chain attached thereto.

   344. The method of claim 342, wherein said hydro- carbon chain is covalently attached to sai d at least one impure element. : 345. The method of claim 344, wherein said hydrocarbon is a residue of a © fatty acid. _— 346. The method of claim 343, wherein said hydrophobic powder is bonded B to said partictalated core material via an adherent layer.

   347. The method of claim 343, wherein said hydrophobic powder comprises

   ". inflatable particulates capable of absorbing fluid when beingg in contact therewith. : 348. The method of claim 347, wherein said inflatable particulates, when in a deflated state, constitute less than 2 percent of the free-flowing hydrophobic aggregate by volume.

   349. The method of claim 347, wherein said inflatable particulates comprise a super absor-bent polymer. . 350. The method of claim 347, wherein ssaid inflatable particulates comprises sodium being cross linked with polyacrylic acid- : 351. The method of claim 347, wherein said inflatable particulates : comprises arti-caking agent.

   352. The method of claim 342, wherein said particulated core material is selected froem the group consisting of sand, gravel, slag, porcelanit, dolomite, porcelain, basalt, quartz sand, coal ash, chalk, zeolite, montmorillonite, agapultite, flint, bentomite, perlite, mica, wood chips, nut shells, sawdust and combinations thereof.

   353. The method of claim 346, wherein said adherent layer is a water-based adherent layer.

   © WO 2005/005566 PCT/IL2004/000635 354, The method of claim 353, wherein said water-based adherent layer cosmprises a water-based gluing agent.

   355. The method of claim 346, wherein said adhe=rent layer comprises a film-forming agent.

   356. The method of claim 355, wherein said adherent layer further comprises a gluing agent.

   357. The method of claim 342, wherein said hydrophobic powder further comprises hydrophobic fumed silica.

   358. The method of claim 342, wherein said free-flowing hydrophobic aggregate further comprises at least one additive selected fronm the group consisting of a coloring agent, a UV resistant agent, a bleaching agent and ar abrasive agent.

   359. A method of waterproofing a reservoir, the metinod comprising: placing a flooring bed of a free-flowing hydrophobic eaggregate over a base of thae reservoir; and placing walls of said free-flowing hydrophobic aggresgate over walls of the reservoir; w~herein at least one of said flooring bed and said walls of said free-flowing hydrophobic aggregate are covered by a protective structure d esigned and constructed ’ to maintain said free-flowing hydrophobic aggregate in place.

   360. The method of claim 359, wherein a thickness. of said flooring bed of free-flowing hydrophobic aggregate is between 4 and 15 cm.

   361. The method of claim 359, further comprising mnixing said free-flowing h=ydrophobic aggregate with lightweight aggregates.

   " 362. The method of claim 359, wherein said protective structure is selected "from the group corsisting of tiles, geotechnic fabric, concrete, plastic and combination thereof. : 363. The method of claim 359, wherein at least one= of said flooring bed and said sidewalls of ssaid free-flowing hydrophobic aggregate comprises an arrangement of hydrophobic br-icks, each being a protective encapsulatioom having a predetermined shape and encapsulating said free-flowing hydrophobic aggregate.

   364. The= method of claim 363, wherein said protective encapsulation is made from a degradable material.

   365. The= method of claim 359, wherein said fi—ee-flowing hydrophobic aggregate comprisees a plurality of differently sized particulate=s, and further wherein at

   . least one of a size distribution of said particulates, a contact aragle between a liquid and said particulates ard a characteristic distance between adjacert particulates is selected so that when the free-flowing hydrophobic aggregate is in cormtact with a liquid having a pressure lower th_an or equal to a predetermined maximal pressure, percolation of the . liquid through the Sfree-flowing hydrophobic aggregate is preve=nted.

   366. The method of claim 365, wherein said liquid iss water.

   367. The method of claim 365, wherein said size distribution is selected so that a maximal diammeter of capillaries formed between said paarticulates is suitable for repealing the liquid...

   368. The method of claim 365, wherein said free-flowing hydrophobic aggregate further comprises inflatable particulates size wise compatible with : capillaries formed tetween said particulates and capable of abssorbing the fluid.

   369. The -1nethod of claim 368, wherein said inflatable particulates, when in a deflated state, coonstitute less than 2 percent of the frese-flowing hydrophobic aggregate by volum-e.

   VO 2005/005566 PCT/IL2004/000635

   370. The method of claim 368, wherein said inflatable particulates comprise a super absorbent polymer. . 371. The method of claim 368, wherein said inflatable particulates <omprises sodium being cross linked with polyacrylic aci-d.

   372. The method of claim 368, wherein said inflatable particulates «comprises anti-caking agent. . 373. The method of claim 361, wherein said ssize distribution is selected so -that the free-flowing hydrophobic aggregate is chara cterized by a predetermined . specific weight. : 374. The method of claim 361, wherein said ssize distribution is selected so

   ©. that the free-flowing hydrophobic aggregate is charactemrized by a minimal absorption : capability.

   375. The method of claim 359, wherein said free-flowing hydrophobic ) aggregate comprises a particulated core material coated bya hydrophobic material. - 376. The method of claim 375, wherein said hydrophobic material is a hydrophobic powder.

   377. The method of claim 376, wherein said ha ydrophobic powder comprises at least one impure element having a hydrocarbon chain attached thereto.

   378. The method of claim 377, wherein said h-ydrocarbon chain is covalently attached to said at least one impure element.

   379. The method of claim 378, wherein said hydrocarbon is a residue of a fatty acid.

   3 80. The method of claim 377, wherein sa-id hydrophobic powder is bonded to said p=articulated core material via an adherent layer.

   3.81. The method of claim 377, wherein said hydrophobic powder comprises © inflatablee particulates capable of absorbing fluid when being in contact therewith.

   . 3g2. The method of claim 381, wherein said inflatable particulates, when in a deflat ed state, constitute less than 2 percent eof the free-flowing hydrophobic aggregate by volume.

   83. The method of claim 381, wherein said inflatable particulates comprise a super absorbent polymer.

   384. The method of claim 381, whemein said inflatable particulates compris-es sodium being cross linked with polyacrylic acid. =385. The method of claim 381, whezein said inflatable particulates compris-es anti-caking agent.

   386. The method of claim 376, wherein said particulated core material is selected from the group consisting of sand, gravel, slag, porcelanit, dolomite, porcelain, basalt, quartz sand, coal ash, chalk, zeolite, montmorillonite, agapultite, flint, bentonite, perlite, mica, wood chips, nut shells, sawdust and combinations thereof.

   387. The method of claim 380, wherein said adherent layer is a water-based adherentt layer. =388. The method of claim 387, wherein said water-based adherent layer compris: €s a water-based gluing agent. : 389. The method of claim 380, wherein said adherent layer comprises a film-formmning agent.

   © WO 2005/005566 PCT/IL2004/€000635

   390. The method of claim 389, where-in said adherent layer further " comporises a gluing agent.

   39]. The method of claim 376, wherein said hydrophobic powder fur—ther comprises hydrophobic fumed silica. p 362. The method of claim 376, whereirm said free-flowing hydrophobic aggreegate further comprises at least one additive sele=cted from the group consistirag of a coloring agent, a UV resistant agent, a bleaching agzent and an abrasive agent.

   393. A method of protecting an object Wouried underground, the mesthod - compprising providing a free-flowing hydrophobic- aggregate and surrounding= the objesct by a layer of said free-flowing hydrophobic aggregate in a manner such_ that . said layer of said free-flowing hydrophobic aggregat-e is interposed between the object

   ". and athe ground.

   394. The method of claim 393, whereim said free-flowing hydrophobic aggregate comprises a plurality of differently sized particulates, and further wherein at least= one of a size distribution of said particulates, a econtact angle between a liquid and said particulates and a characteristic distance between adjacent particulates is seleected so that when the free-flowing hydrophobic aggregates is in contact with a liquid heaving a pre=ssure lower than or equal to a predetermined maaximal pressure, percolation of the liquid through the free-flowing hydrophobic aggregate is prevented.

   395. The method of claim 394, wherein saiid liquid is water.

   396. The method of claim 394, wherein s aid size distribution is selecte=d so that a maximal diameter of capillaries formed betwezen said particulates is suitabMe for repe=aling the liquid.

   397. The method of claim 394, further comprising inflatable particulates size. wises compatible with capillaries formed between said particulates and capab-le of abscotbing the fluid.

   " 398. The method of claim 397, wherein said imflatable particulates, when in a deflated stzate, constitute less than 2 percent of the free-flowing hydrophobic : aggregate by wolume, oC 399. The method of claim 397, wherein said imflatable particulates comprise a super absortoent polymer.

   400. The method of claim 397, wherein said inflatable particulates comprises soc3ium being cross linked with polyacrylic acid.

   401. The method of claim 397, wherein. said inflatable particulates comprises an#ti-caking agent. } 402, The method of claim 394, wherein said size distribution is selected so that the free=-flowing hydrophobic aggregate is characterized by a predetermined specific weigzht. 403, The method of claim 394, wherein said size distribution is selected so . that the free- flowing hydrophobic aggregate is characterized by a minimal absorption capability.

   404. The method of claim 394, wherein said size distribution is selected 50 that the free-—flowing hydrophobic aggregate is characterized by predetermined thermal properties.

   405. The method of claim 394, wherein said size distribution is selected so that the fre=e-flowing hydrophobic aggregate is chmaracterized by predetermined acoustical isclation ability. oo 406. The method of claim 394, wherein said. size distribution is selected so that the free=-flowing hydrophobic aggregate is capabole of allowing evaporation of liquid.

   - 407. The method of claim 393, wherein said free-flowing hydrophobi«c aggregate comprises a particulated core material coated by a hydrophobic material. . 408. The method of claim 407, wherein said hydrophobic material is a "hydrophobic powder. 409, The method of claim 408, wherein said hydrophobic powder comprises at least one impure element having a hydrocarbon. chain attached thereto.

   410. The method of claim 409, wherein said hydrocarbon chain is covalently attached to said at least one impure element.

   411. The method of claim 410, wherein said hydrocarbon is a residue of a fatty acid. . 412. The method of claim 409, wherein said hydrophobic powder is bonded to said particulated core material via an adherent Rayer.

   413. The method of claim 409, wherein said hydrophobic powder comprises inflatable particulates capable of absorbing fluid wvhen being in contact therewith.

   414. The method of claim 413, wherein said inflatable particulates, when Jn a deflated state, constitute less than 2 percemt of the free-flowing hydrophobic aggregate by volume.

   415. The method of claim 413, wherein said inflatable particulates comprisse a super absorbent polymer.

   416. The method of claim 413, wrherein said inflatable particulates comprises sodium being cross linked with polyacarylic acid.

   417. The method of claim 413, wherein said inflatable particulatees comprises anti-caking agent.

   418. The method of claim 408, whereira said particulated core material is selected from the group consisting of sand, gravel, slag, porcelanit, dolomite, porcelain, basalt, quartz sand, coal ash, chalk, zeolite, montmorillonite, agapultite, flint, bentonite, perlite, mica, wood chips, nut shells, sawdust and combinations thereof. Bh 419. The method of claim 412, wherein said adherent layer is a water-based adherent layer.

   420. The method of claim 419, where-in said water-based adherent layer comprises a water-based gluing agent.

   421. The method of claim 412, wherein said adherent layer comprises a film-forming agent. :

   422. The method of claim 421, wimerein said adherent layer further comprises a gluing agent.

   423. The method of claim 408, wherein said hydrophobic powder further : "comprises hydrophobic fumed silica.

   424. The method of claim 408, whemrein said free-flowing hydrophobic . aggregate further comprises at least one additive selected from the group consisting of a coloring agent, a UV resistant agent, a bleachings, agent and an abrasive agent.

   425. A hydrophobic composition for protecting an underground object, comprising a thermally conductive free-flowEng hydrophobic aggregate and a dielectric free-flowing hydrophobic aggregate, said thermally conductive free-flowing hydrophobic aggregate and said dielectric free-fRowing hydrophobic aggregate being mixed in a predetermined ratio selected so as to- electrically isolate the underground object while allowing transportation of heat therefrom.

   426. The hydrophobic co position of claim 425, wherein the underground object is selected from the group consisting of an underground electrical cable, an underground electrical wire, ara underground communication cable and an underground communication wire.

   427. The hydrophobic co-mposition of claim 425, wherein at least one of said } thermally conductive free-flowing hydrophobic aggregate and said dielectric free- flowing hydrophobic aggregate comprises a particulated core materi al coated by a . hydrophobic material. } 428. The hydrophobic composition of claim 427, wherein sa id hydrophobic "material is a hydrophobic powder. Co 429. The hydrophobic composition of claim 428, wherein said hydrophobic powder has a distinguishable color. x 430. The hydrophobic ceomposition of claim 428, wherein s aid particulated "core material is further coated by am coloring coat. . 431. The hydrophobic composition of claim 430, wherein said coloring coat } is water resistant.

   432. The hydrophobic composition of claim 425, further comprising © inflatable particulates size wis.e compatible with capillaries formed between particulates of said thermally commductive free-flowing hydrophobic a _ggregate and/or said dielectric free-flowing hydrosphobic aggregate, said inflatable particulates being capable of absorbing fluid.

   433. The hydrophobic ecomposition of claim 432, whereira an absorption capability of said inflatable particialates is from about 100 to about 500 QO by weight.

   a 434. The hydrophobsic composition of claim 432, wherein a freezing temperature of said inflatable goarticulates below about —20 degrees centigrade, both im an inflated state and in a deflated state of said inflatable particulates.

   435. The hydrophobic composition of claim 432, wherein said inflatabl.e particulates, when in a deflated state, constitute less than 2 percent of the free-flowin_g hydrophobic aggregate by volume.

   436. The hydrophobic composition of claim 432, wherein a diameter of said inflatable particulates is from about 1 micrometer to about 1000 micrometers.

   437. The hydrophobic composition of claim 432, wherein said inflatable particulates comprise a super absorbent polymer. \

   438. The hydropho bic composition of claim 432, wherein said inflatable particulates comprises sodium being cross linked with polyacrylic acid.

   439. The hydropho bic composition of claim 432, wherein said inflatab le particulates comprises anti-ca:king agent.

   440. The hydropho®bic composition of claim 428, wherein said hydrophob=ic powder comprises at least ore impure element having a hydrocarbon chain attache=d : thereto.

   441. The hydrophobic composition of claim 440, wherein said hydrocarbOn : chain is covalently attached te said at least one impure element.

   442. The hydrophobic composition of claim 441, wherein said hydrocarbcon is a residue of a fatty acid.

   443. The hydrophobic composition of claim 428, wherein said hydrophot=ic powder is bonded to said particulated core material via an adherent layer.

   444. The hydrophobic composition of claim 443, wherein said adherent _ layer is a water-based adherent layer. . 445. The hydrophobic composition of claim 444, wherein. said water-based _ adherent layer comprises a water-based gluing agent.

   446. The hydrophobic composition of claim 443, wherein said adherent . layer comprises a filim-forming agent. , 447. The hydrophobic composition of claim 446, wherein said adherent . layer further comprisses a gluing agent.

   448. The hydrophobic composition of claim 428, wherein said hydrophobic powder further comprises hydrophobic fumed silica.

   449. The Thydrophobic composition of claim 428, further comprising at least .» one additive selected from the group consisting of a UV resistant agent, a bleaching : agent and an abrasiwe agent.

   450. The hydrophobic composition of claim 428, wheresin said particulated core material is selected from the group consisting of sand, grav-el, slag, porcelanit, dolomite, porcelaim, basalt, quartz sand, coal ash, chalk, zeolite, montmorillonite,

   . agapultite, flint, bentonite, perlite, mica, wood chips, nut shells, sawdust and combinations thereof.

   451. The hydrophobic composition of claim 425, wherein at least one of said thermally conductive free-flowing hydrophobic aggregate and said dielectric free- flowing hydrophobic aggregate comprises a plurality of differently” sized particulates.

   452. The hydrophobic composition of claim 451, wherein at least one of a size distribution of said differently sized particulates, a contact aragle between a liquid and said differently sized particulates and a characteristic distance between adjacent particulates is sel ected so that when a layer of the hydrophobic composition is in contact with a liquid havimg a pressure lower than or equal to a predetermined maximal pressure, percolation of said liquid through the hydrophobic composition is prevented.

   453. The hydrophobic composition of claim 452, wherein said liquid is water. ’ ) 454. The hydropheobic composition of claim 452, wherein said layer has a thickness from about 1 cm to about 10 cm and further wherein said predetermined maximal pressure is equival<ent to a column of water having a height above 30 cm.

   455. The hydrophobic composition of claim 452, wherein said size distribution is characterized by a variance ranging from 1 micrometer to 1400 micrometer.

   456. The hydrophobic composition of claim 452, wherein said size distribution is selected so tthat a maximal diameter of capillaries formed between said particulates is suitable for repealing the predetermined maximal pressure of the liquid. co 457. The hydrophobic composition of claim 452, wherein said size distribution is selected so €£hat a maximal diameter of capillaries formed between said particulates is from 1 nanommeter to 500 nanometers.

   458. A method o f protecting an underground object, the method comprising: providing a hydro-phobic composition having a thermally conductive free- flowing hydrophobic aggregate and a dielectric free-flowing hydrophobic aggregate; and surrounding the object by a layer of said hydrophobic composition in a manner such that said layer of sai«] hydrophobic composition is interposed between the object and the ground; said thermally conductive free-flowing hydrophobic aggregate and said dielectric free-flowing hy=drophobic aggregate being mixed in a predetermined ratio selected so as to electrically isolate the underground object while allowing transportation of heat therefrom.

   459. The method of claim 458, wherein the underground eobject is selected from the group consisting of an underground electrical cable, an underground electrical wire, an underground communication cable and an underground communication wire.

   460. The method of claim 458, wherein at least one eof said thermally : conductive free-flowing hydrophobic aggregate and said dielectric free-flowing hydrophobic aggregate comprises a particulated core material coated_ by a hydrophobic material. -

   461. The method of claim 460, wherein said hydrophobic material is a . hydrophobic powder.

   462. The method of claim 461, wherein said hydrophobic powder has a distinguishable color.

   463. The method of claim 461, wherein said particulateed core material is : Lo further coated by a coloring coat.

   464. The method of claim 463, wherein said coloring coa=t is water resistant.

   465. The method of claim 458, wherein said hydrophobic composition further comprises inflatable particulates, size wise compatible with capillaries formed between particulates of said thermally conductive free-flowing hyclrophobic aggregate and/or said dielectric free-flowing hydrophobic aggregate, said inmflatable particulates being capable of absorbing fluid.

   466. The method of claim 465, wherein an absorptiomn capability of said inflatable particulates is from about 100 to about S000 by weight.

   Be 133 - 467_. The method of claim 465, wherein a freezing temperature of said EE inflatable particulates below about ~20 degrees centigr=ade, both in an inflated state and in a deflated state of said inflatable particulates. 4653. The method of claim 465, wherein said imflatable particulates, when in a deflatedi state, constitute less than 2 percent of fhe free-flowing hydrophobic aggregate by volume. 46:9. The method of claim 465, wherein =a diameter of said inflatable particulatees is from about 1 micrometer to about 1000 nicrometers.

   470. The method of claim 465, wherein said inflatable particulates comprise a super allbsorbent polymer. : 4-71. The method of claim 465, wherein said inflatable particulates } i comprises sodium being cross linked with polyacrylic =acid. 4:72. The method of claim 465, wherein said inflatable particulates comprisecs anti-caking agent. ~473. The method of claim 461, wherein saicl hydrophobic powder comprises at least @one impure element having a hydrocarbon chamin attached thereto. «474. The method of claim 473, wherein sail hydrocarbon chain is covalently attache to said at least one impure element.

   475. The method of claim 474, wherein s=aid hydrocarbon is a residue of a oe fatty acid.

   476. The method of claim 461, wherein samid hydrophobic powder is bonded to said particulated core material via an adherent layeer.

   477. The method of clainm 476, wherein said adherent layeris a water-base=d

   +. adherent layer.

   478. The method of clairm 477, wherein said water-based adherent layer comprises a water-based gluing agerat. oo 479. The method of claim 476, wherein said adherent layer comprises & filin-forming agent.

   480. The method of claim 479, wherein said adherent layer further comprises a gluing agent.

   481. The method of claim 461, wherein said hydrophobic powder further comprises hydrophobic fumed silica.

   . 482. The method of claim. 461, wherein said hydrophobic composition "further comprises at least one additive selected from the group consisting of a UV © resistant agent, a bleaching agent and an abrasive agent. oo 483. The method of claim 461, wherein said particulated core material is "selected from the group consisting of sand, gravel, slag, porcelanit, dolomite, . porcelain, basalt, quartz sand, coal ash, chalk, zeolite, montmorillonite, agapultite, "flint, bentonite, perlite, mica, wood «hips, nut shells, sawdust and combinations thereof.

   484. The method of claim 4#58, wherein at least one of said thermally conductive free-flowing hydrophobic aggregate and said dielectric free-flowing hydrophobic aggregate comprises a plurality of differently sized particulates.

   485. The method of claim 484, wherein at least one of a size distribution of said differently sized particulates, a contact angle between a liquid and said differently sized particulates and a characteristic distance between adjacent particulates is selected so that when a layer of said hydrophobic composition is in contact with a liquid having a pressure lower than or equal to 2 predetermined maximeal pressure, percolation of said liquid through said hydrophobic composition is prevented.

   486. The method of claim 485, wherein said liquidll is water.

   487. The method of claim 485, wherein said layer has a thickness from _ about 1 cm to about 10 cm and further wherein said predet-ermined maximal pressure is equuivalent to a column of water having a height above 30 cm.

   488. The method of claim 485, wherein ssaid size distribution is "characterized by a variance ranging from 1 micrometer to 14300 micrometer.

   489. The method of claim 485, wherein said sizes distribution is selected so that a maximal diameter of capillaries formed between said. particulates is suitable for repealing the predetermined maximal pressure of the liquid.

   490. The method of claim 485, wherein said sizes distribution is selected so that a maximal diameter of capillaries formed between said particulates is from 1

   . nanometer to 500 nanometers.

   491. A method of manufacturing a hydrophobic «composition for protecting an underground object, the method comprising providing a thermally conductive free-flowing hydrophobic aggregate; providing a dielectric free-flowing hydrophobic aggregate; and : mixing said thermally conductive free-flowing hydrophobic aggregate and said dielectric free-flowing hydrophobic aggregate in a predeternmined ratio; said predetermined ratio being selected so as to allow electrical isolation of the ~ underground object and transportation of heat therefrom.

   492. The method of claim 491, wherein the underground object is selected froma the group consisting of an underground electrical cable, an underground electrical wire, an underground communication cable and an underground comanunication wire.

   493. “The method of claim 491, wherein at least one o f said thermally . conductive fre-e-flowing hydrophobic aggregate and said dielectric free-flowing hydrophobic agzgregate comprises a particulated core material coated by a hydrophobic material.

   494. The method of claim 493, wherein said hydrophotoic material is a : hydrophobic poswder.

   495. ~The method of claim 494, wherein said hydrophobic powder has a distinguishable color.

   496. "The method of claim 494, wherein said particulated core material is "further coated bey a coloring coat.’ g 497. Whe method of claim 496, wherein said coloring coat is- water resistant.

   498. Whe method of claim 491, further comprising mixingg said thermally conductive frees-flowing hydrophobic aggregate and said dielectmic free-flowing hydrophobic ag=gregate with inflatable particulates being size wise compatible with capillaries formed between particulates of said thermally conductive free-flowing hydrophobic aggregate and/or said dielectric free-flowing hydrophobi«c aggregate, said . inflatable particulates being capable of absorbing fluid.

   499. The method of claim 498, wherein an absorption campability of said inflatable particcalates is from about 100 to about 5000 by weight.

   500. The method of claim 498, wherein a freezing temperature of said . inflatable particmuilates below about —20 degrees centigrade, both in zn inflated state and in a deflated® state of said inflatable particulates.

   501. The method of claim 498, wherein said inflatable particulates, when in a deflated states, constitute less than 2 percent of the free-flowirag hydrophobic aggregate by vol ume.

   Wa 2005/005566 PCT/IL2004/000635

   502. The method of claim 498, wherein =a diameter of said inflatable . paxticulates is from about 1 micrometer to about 1000 nnicrometers.

   503. The method of claim 498, wherein said inflatable particulates comprise > a super absorbent polymer.

   504. The method of claim 498, wherein said inflatable particulates comprises sodium being cross linked with polyacrylic acid.

   505. The method of claim 498, whereimn said inflatable particulates comprises anti-caking agent.

   506. The method of claim 494, wherein said _ hydrophobic powder comprises at least one impure element having a hydrocarbon chaim attached thereto.

   507. The method of claim 506, wherein said “hydrocarbon chain is covalently at tached to said at least one impure element.

   508. The method of claim 507, wherein saiad hydrocarbon is a residue of a ) fa tty acid.

   509. The method of claim 494, wherein said hydrophobic powder is bonded tor said particulated core material via an adherent layer.

   510. The method of claim 509, wherein said adherent layer is a water-based aclherent layer.

   511. The method of claim 510, wherein s=aid water-based adherent layer comprises a water-based gluing agent.

   512. The method of claim 509, wherein s=id adherent layer comprises a film-forming agent.

   513. - The method of claim 512, wherein said adherent layer further comprises a gluing agent. ) 514. The method of claim 494, wherein said hydrophobic powder further comprises hydrophobic fumed silica.

   515. The method of claim 494, further comprising mixing said thermally ‘conductive free-flowing hydrophobic aggregate and said dielectric free-flowing hydrophobic aggregate with at least one additive selected from the group consisting of a UV resistant agent, a bleaching agent and an abrasive agent.

   516. The method of claim 494, wherein said particulated core material is selected from the group consisting of sand, gravel, slag, porcelanit, dolomite, porcelain, basalt, quartz sand, coal ash, chalk, zeolite, montmorillonite, agapultite, - flint, bentonite, perlite, mica, wood chips, nut shells, sawclust and combinations thereof. E 517. ~The method of claim 491, wherein at least one of said thermally ) - conductive frese-flowing hydrophobic aggregate and said ielectric free-flowing "+ hydrophobic ag=gregate comprises a plurality of differently sized particulates.

   518. The method of claim 517, wherein at least one o fa size distribution of said differently sized particulates, a contact angle between a liqumid and said differently sized particulates and a characteristic distance between adjacent particulates is selected so that when a 1 ayer of the hydrophobic composition is in contact with a liquid having a pressure lowest than or equal to a predetermined maximal pr-essure, percolation of + said liquid through the hydrophobic composition is prevented.

   519. The method of claim 518, wherein said liquid is water.

   520. The method of claim 518, wherein said layer kas a thickness from about 1 cm to aboout 10 cm and further wherein said predetermiraed maximal pressure is equivalent to as column of water having a height above 30 cm. :

   521. The method of claim 518, wherein said size distribution is characterized by a variance ranging from 1 micronmeter to 1400 micrometer.

   522. The method of claim 518, whereimm said size distribution is selected so that a maximal diameter of capillaries formed bet-ween said particulates is suitable for repealing the predetermined maximal pressure of the liquid.

   523. The method of claim 518, whereir said size distribution is selected so that a maximal diameter of capillaries formed Wbetween said particulates is from 1 nanometer to 500 nanometers.

   524. A method of preparing an area for plants cultivating, comprising providing a bed of a free-flowing hydrophobic aggregate onto the area and covering said bed of a free-flowing hydrophobic aggregates by a layer of soil, thereby preparing an area for plants cultivating,

   525. The method of claim 524, whesrcin said bed of said free-flowing hydrophobic aggregate comprises an arrangemen-t of hydrophobic patches, each being a protective encapsulation having a predetermined shape and encapsulating said free- ‘ flowing hydrophobic aggregate.

   526. The method of claim 525, wherein said protective encapsulation is made from a degradable material.

   527. The method of claim 525, wherein said hydrophobic patches are : arranged such that at least one space is formed be-tween adjacent hydrophobic patches.

   528. The method of claim 524, whereir said further comprising mixing said free-flowing hydrophobic aggregate with lightweri ght aggregates.

   529. The method of claim 524, further comprising covering said bed of said free-flowing hydrophobic aggregate by a super at>sorbent polymer.

   530. The method of claim 524, further comprising positioning at least one water collection channel for allowing conveyance of watem into said soil.

   531. The method of claim 524, further compris3ing surrounding said layer of soil by a protective barrier.

   532. The method of claim 531, wherein said protective barrier comprises said free-floswing hydrophobic aggregate. : CT) 533_ The method of claim 524, wherein said bed of free-flowing hydrophobi c aggregate is designed and constructed to Facilitate desalination of non- : desalted water present thereunder, said desalination beeing effected by passage of desalted vapors of said non-desalted water through szid bed of said free-flowing hydrophobic aggregate. : 534_ The method of claim 524, wherein sadid free-flowing hydrophobic aggregate comprises a plurality of differently sized particulates, and further wherein at least one of a size distribution of said particulates, a conteact angle between a liquid and said particualates and a characteristic distance between acjacent particulates is selected so that whe=n the free-flowing hydrophobic aggregate is in contact with a liquid having

   . a pressure Bower than or equal to a predetermined maximal pressure, percolation of the liquid throvagh the free-flowing hydrophobic aggregate is prevented.

   535. The method of claim 534, further comprissing inflatable particulates size wise compwatible with capillaries formed between saidl particulates and capable of "absorbing the fluid. - 536s. The method of claim 535, wherein said imnflatable particulates, when in a deflated state, constitute less than 2 percent of tthe free-flowing hydrophobic aggregate by volume.

   537. The method of claim 535, wherein said irflatable particulates comprise a super abssorbent polymer.

   538. The method of claim 535, wherein said inflatable particulates ~ comprises sodium being cross linked with polyacrylic acid.

   539. The method of claim 535, wherein said inflatable particulates

   ". comprises anti-caking agent.

   540. The method of cla-im 534, wherein said size distribution is selected sso that the free-flowing hydrophobwic aggregate is characterized by a predetermine=d specific weight. . . 3 . .

   541. The method of claim 534, wherein said size distribution is selected s0 that the free-flowing hydrophobic aggregate is characterized by a minimal absorptioen capability.

   542. The method of cla_im 534, wherein said size distribution is selected so E that the free-flowing hydrophobic aggregate is characterized by predetermined thermzal : properties. ~ ‘ 543. The method of clasim 534, wherein said size distribution is selected so that the free-flowing hydrophobiic aggregate is capable of allowing evaporation of liquid.

   544. A method of preparing a salt-free area on a salty soil, comprisirmg providing a bed of a free-flowing hydrophobic aggregate onto the salty soil amd covering said bed of said free-flowing hydrophobic aggregate by non-salty soil, thereby preparing the salt-free are=a.

   545. The method of clam 544, wherein said further comprising mixing sar.d - free-flowing hydrophobic aggregate with lightweight aggregates.

   546. The method of clai-m 544, further comprising covering said bed of free=- flowing hydrophobic aggregate by= a super absorbent polymer.

   547. The method of claim 544, wherein said ‘bed of free-flowing hydrophobic aggregate is designed and constructed to facilitate desalination of non- "desalted water present thereunder, said desalinatior being effected by passage of desalted vapors of said non-desalted water througlm said bed of said free-flowing: - hydrophob-ic aggregate.

   548. The method of claim 544, wherein said free-flowing hydrophobic aggregate comprises a plurality of differently sized pemrticulates, and further wherein at- least one of a size distribution of said particulates, a contact angle between a liquid andl said particulates and a characteristic distance betweera adjacent particulates is selected so that when the free-flowing hydrophobic aggregate is in contact with a liquid having= a pressure lower than or equal to a predetermined masximal pressure, percolation of thes liquid through the free-flowing hydrophobic aggregates is prevented.

   540. The method of claim 548, further comprising inflatable particulates size wise compatible with capillaries formed between said particulates and capable off absorbing the fluid. 550). The method of claim 549, wherein sai.d inflatable particulates, when irm a deflated state, constitute less than 2 percent o f the free-flowing hydrophobic aggregate Iby volume.

   55M. The method of claim 549, wherein saied inflatable particulates comprise a super absorbent polymer.

   552. The method of claim 549, wheresin said inflatable particulates comprises sodium being cross linked with polyacrylic= acid.

   553. The method of claim 549, wherein said inflatable particulates comprises anti-caking agent.

   RU

   554. Thme method of claim 548, wherein said size distribution is selected so that the free-flowing hydrophobic aggregate is characterized by a predeterminmed specific weight. : 555. Thee method of claim 548, wherein said size distribution is selected so "that the free-flowing hydrophobic aggregate is characterized by a minimal absorption capability.

   556. The method of claim 548, wherein said size distribution is selected sso : that the free-flowimng hydrophobic aggregate is characterized by predetermined thermazal properties.

   557. The= method of claim 548, wherein said size distribution is selected s © } that the free-flowing hydrophobic aggregate is capable of allowing evaporation c»f liquid.

   558. A h_ydrophobic composite comprising a core material coated by =a hydrophobic material, said hydrophobic material being bonded to said core materia’ : via a water-based actherent layer. .

   559. The hydrophobic composite of claim 558, wherein said water-based. } adherent layer comprises a water-based gluing agent.

   560. The Eydrophobic composite of claim 559, wherein said water-based gluing agent is a bittmmen-latex paste.

   561. The lmydrophobic composite of claim 558, wherein said hydrophobic material is selected from the group consisting of a hydrophobic powder comprising at least one impure elemment having a hydrocarbon chain attached thereto, hydrophobic fumed silica, molten goolypropylene, and any mixture thereof.

   562. The hwdrophobic composite of claim 561, wherein said hydrocarbon chain comprises at least 10 carbon atoms.

   563. Thee hydrophobic composite of claim 5651, wherein said hydrocarbon chain is covalently attached to said at least one impure el_ement.

   564. Th_e hydrophobic composite of claim 563%, wherein said hydrocarbon is a residue of a fatt~y acid having at least 12 carbon atoms.

   565. Time hydrophobic composite of claim 5654, wherein said fatty acid is selected from the= group consisting of stearic acid, lauric acid, myristic acid, palmitic acid, oleic acid, 1&nolenic acid and arachidonic acid. : 566. The hydrophobic composite of claim 61, wherein said element is selected from thes group consisting of a metallic element, a semi-metallic element and : ~ atransition metal lic element.

   567. The hydrophobic composite of claim 5-61, wherein said at least one element is selected from the group consisting of magnessium, calcium, aluminum, zinc, sodium, barium, zirconium, manganese, titanium, vemnadium, chromium, iron and combinations the=reof.

   568. Thhe hydrophobic composite of claim 5 61, wherein said hydrophobic powder has an average particle size ranging between 0.02 micron and 50 microns.

   569. The hydrophobic composite of claim 5561, wherein said hydrophobic powder has a sur-face area ranging between 1 m?/gram a nd 60 m’/gram.

   570. Thhe hydrophobic composite of claim 5588, wherein said core material is selected from thes group consisting of a particulate matewrial and a granulate material. SA 571. The hydrophobic composite of claim 5538, wherein said core material is selected from the group consisting of sand, gravel, slag, porcelanit, dolomite, porcelain, basalt, quartz sand, coal ash, chalk, zeolit-e, montmorillonite, agapultite, : flint, bentonite, perlite, mica, wood chips, nut shells, sawdust and combinations thereof.

   572. The hydrophobic composite of claim 5 70, wherein said core material © hasan average particle size ranging between 25 millimesters and 5 microns.

   573. The hydrophobic composite of claim 57 1, wherein said core material is quartz sand.

   574. The hydrophobic composite of claim =561, wherein said hydrophobic materi=al comprises a mixture of said hydrophobic powcder and said hydrophobic fumed

   575. The hydrophobic composite of claim =574, wherein said hydrophobic fumed silica constitutes between 1 and 99 weight percentages of said hydrophobic : powde=r. '

   576. The hydrophobic composite of claim 5 58, wherein said adherent layer : constit-utes between about 0.5 and about 7 weight percentages of the hydrophobic © compomsite. . 577. The hydrophobic composite of claim 558, wherein said hydrophobic materisal constitutes between about 0.1 and about 5 weight percentages of the "hydrophobic composite.

   578. The hydrophobic composite of claim 558, further comprising at least one adllditive selected from the group consisting of a coloring agent, a UV resistant agent, ableaching agent and an abrasive agent.

   579. A method of preparing the hydrophob-ic composite of claim 558, the method comprising: } admixing a core material and an aqueous adhesrent mixture including a water- based geluing agent and an aqueous solvent; removing said aqueous solvent to thereby to theereby provide said core material havingz applied thereon said water-based adherent layer; and co ating said core material having apgplied thereon said water-based adherent layer with. said hydrophobic material, thereby “providing said hydrophobic composite. 580). The method of claim 579, wherein a concentration of said water-based gluing ageent in said aqueous adherent mircture ranges between about I weight percentage= and about 99 weight percentages. 581 . The method of claims 100, furttmer comprising drying said core material prior to saicl admixing,

   582. The method of claims 100, furthest comprising drying said core material having applied thereon said water-based adhererat layer prior to said coating.

   583. The method of claim 579, further- comprising, after said coating, curing said hydroplmobic composite.

   a. 584. The method of claim 583, wherein said curing is performed for a time period ranging between 1 and 30 days.

   585. The method of claim 579, wherein removing said aqueous solvent is : performed by tumble drying.

   586. The method of claim 579, further— comprising, prior to said coating, admixing said core material having thereon said water-based adherent layer with an : : additive selecte=d from the group consisting of a coloring agent, a UV resistant agent, a bleaching agenwt and an abrasive agent.

   587. Whe method of claim 579, wherein =said core material is selected from the group consisting of a particulate material and a granulate material.

   588. The method of claim 587, wherein s aid core material is selected from the group consi sting of sand, gravel, slag, porceL anit, dolomite, porcelain, basalt,

   quartz san d, coal ash, chalk, zeolite, montmorillonite, agapumltite, flint, bentonite, perlite, mica, wood chips, nut shells, sawdust and combinations thereof.

   589. The method of claim 587, wherein said core material has an average particle siz=e ranging between 25 millimeters and 5 microns. 590). The method of claim 588, wherein said core mate=rial is quartz sand. 59-1. The method of claim 579, wherein said water—-based adherent layer constitutess between about 0.5 and about 7 weight percentage s of said hydrophobic composite=. 59-2. The method of claim 579, wherein said hydrophobic material constitutes between about 0.1 and about 5 weight percentage=s of said hydrophobic composite=. ) 593, A plant cultivating method, comprising: To preoviding a bed of a free-flowing hydrophobic aggregate an area, . covering said bed of a free-flowing hydrophobic aggregaate by a layer of soil; plaanting a plant in said layer of soil; and apeplying aqueous liquid under said bed of a free-flowing hydrophobic aggregate= thereby cultivating the plant. : 554, The method of claim 593, wherein said aqueous liquid is salty water. 5095. The method of claim 593, wherein said bec of said free-flowing hydropho-bic aggregate comprises an arrangement of hydrophobic patches, each being a protective encapsulation having a predetermined shape and encapsulating said free- flowing lmydrophobic aggregate. :

   566. The method of claim 595, wherein said prot-ective encapsulation is made fromm a degradable material.

   © WO 2005/0055566 PCT/IL2004/0 ©0635

   507. The method of claim 595, wher—ein said hydrophobic patches are arranged suech that at least one space is formed between adjacent hydrophobic patcines.

   SO8.. The method of claim 593, wherein said further comprising mixing said "free-flowing hydrophobic aggregate with lightweight aggregates. 599_ The method of claim 593, further comprising covering said bed of ~ said free-flowing hydrophobic aggregate by a super ab sorbent polymer. 600 . The method of claim 593, further— comprising positioning at leas& one water colle=ction channel for allowing conveyance= of water under said bed of said free- flowing hyedrophobic aggregate. : 601 . The method of claim 593, further comprising surrounding said lay=er of soil by a protective barrier.

   602. The method of claim 601, wherein said protective barrier comprises said free-fl owing hydrophobic aggregate. :

   60%. The method of claim 593, vevherein said bed of free-floswing hydrophob ic aggregate is designed and constructed to facilitate desalination of non- desalted water present thereunder, said desaliraation being effected by passagse of desalted v-apors of said non-desalted water thr—ough said bed of said free-flowing hydrophobic aggregate. 602%. The method of claim 593, whesrein said free-flowing hydrophobic aggregate ecomprises a plurality of differently sizeed particulates, and further wherein at least one o=f a size distribution of said particulates, a contact angle between a liqui_d and said particulates and a characteristic distance bet-ween adjacent particulates is seMected so that wheen the free-flowing hydrophobic aggre=gate is in contact with a liquid heaving a pressure lower than or equal to a predeterminec maximal pressure, percolation -of the liquid thro ugh the free-flowing hydrophobic aggr-egate is prevented.

   605. The method of claim 604, further comprising inflatable particulates size "wise compatible with capillaries formed between said particulates and capable of absorbing the fluid. ~ 606. The method of claim 603, wherein said inflatable particulates, when in © a deflated state, constitumte less than 2 percent of the free-flowing hydrophobic : aggregate by volume.

   607. The method of claim 605, wherein said inflatable particulates comprise a super absorbent polymer. : 608. The metheod of claim 605, wherein said inflatable particulates comprises sodium being cross linked with polyacrylic acid. : 609. The meth od of claim 605, wherein said inflatable particulates - comprises anti-caking age=nt.

   610. The method of claim 604, wherein said size distribution is selected so» ) that the free-flowing hy=drophobic aggregate is characterized by a predetermined . specific weight.

   611. The method of claim 604, wherein said size distribution is selected so» that the free-flowing hyd-Tophobic aggregate is characterized by a minimal absorptiora \ capability.

   612. The method of claim 604, wherein said size distribution is selected so ’ that the free-flowing hydrophobic aggregate is characterized by predetermined thermall properties.

   613. The method of claim 604, wherein said size distribution is selected sO that the free-flowing hysdrophobic aggregate is capable of allowing evaporation o=f : liquid.

   a 150

   614. A method of storing a container— containing an oily substance, the methoed comprising positioning the container in 2 dike and surrounding the container by a layer of a free-flowing hydrophobic aggregate in a manner such that said layer of” - said froee-flowing hydrophobic aggregate is intergposed between the container and the grounad.

   615. The method of claim 614, whe=rein said free-flowing hydrophobic aggregate is selected so as to allow absorption of the oily substance.

   616. The method of claim 614, whereima the oily substance is petrol.

   617. The method of claim 615, fursther comprising positioning sensors sensitive to the oily substance in said dike ancl covering said sensors by said free- flowi-ng hydrophobic aggregate, so as to prevent “water from reaching said sensors.

   618. The method of claim 614, wheercin said free-flowing hydrophobic aggresgate comprises a particulated core material coated by a hydrophobic material.

   619. The method of claim 618, whesrein said hydrophobic material is a hydrophobic powder.

   620. The method of claim 619, wherein said hydrophobic powder comprises at lesast one impure element having a hydrocarbosn chain attached thereto.

   621. The method of claim 620, wherein said hydrocarbon chain is covalentky attacThed to said at least one impure element.

   622. The method of claim 621, whereein said hydrocarbon is a residue of a fatty— acid.

   623. The method of claim 620, where=in said hydrophobic powder is bonded to sawid particulated core material via an adheren_t layer.

   624. The method of claim 620, wherein said hy=drophobic powder comprises inflatamble particulates capable of absorbing fluid when bei ng in contact therewith.

   625. The method of claim 619, wherein said —particulated core material is selectesd from the group consisting of sand, gravel, .slag, porcelanit, dolomite, porceliain, basalt, quartz sand, coal ash, chalk, zeolite, montmorillonite, agapultite, "flint, bentonite, perlite, mica, wood chips, nut shells, sawdust and combinations thereosf. : 626. The method of claim 619, wherein said hydrophobic powder further comprises hydrophobic fumed silica.

   627. The method of claim 619, wherein sai-d free-flowing hydrophobic aggregate further comprises at least one additive selected from the group consisting of a coloring agent, a UV resistant agent, a bleaching agent aand an abrasive agent.