EP0658231A1 - Water proofing liner - Google Patents

Abstract

There is described a water-proofing material (10) basically made from a plastic mass containing a liquid and particulate smectite clay, usually montmorillonite such as bentonite, which can be united with a carrier sheet (20). The plastic mass can contain aqueous and/or non-aqueous liquid which can be expelled after forming. The smectite clay can be a smectite liner intercalation complex and the mass is desirably formed by extrusion, in the latter case preferably during reaction of the clay and can have a density of at least 1000 kg/m-3 and can be 1 m or more wide.

Description

WATER PROOFING LINER

This invention relates to a waterproofing material suitable for waterproofing ponds, lakes, lagoons or comparable sites whereby water is retained, or wherein waste is deposited and the ground beneath has to be protected against leakage of aqueous or other liquid. The material can alεo be used in relation to water proofing structures, covering contaminated land to prevent flow of water into such contaminated land and lining trenches which separate contaminated areas from clear areas. The material can also be used as roofing material on flat or sloping roofs. Several materials have been proposed in the past which include a layer of swellable smectite such as montmorillonite and/or sponite incorporated within the material to act as the sealing agent. The montmorillonite has been carried by a support layer or base which has been provided in various ways. A support layer acts as protection but also gives additional strength within the material.

European patent number 59625 (CLEM) describes a waterproofing material which is a laminate comprising a fabric base, particles of montmorillonite adhered to the base and a scrim adhered over the montmorillonite particles to retain them on the base. The CLEM specification requires as an essential feature thereof that the base be capable of venting gas. Although venting of gas from beneath a contained body of water or other matter can be an advantage, it is a great disadvantage to incorporate such vendibility into the actual base. Although there are few sites where venting is necessary it is, when venting is needed, desirable to provide a separate venting layer quite separate from the waterproofing material overlapping the first sheet (10) . The sheet (10) haε a venting base (13) , a layer of montmorillonite (14) adhered to the base (13) and a scrim (15) on top of the montmorillonite. In similar manner sheet (12) has base (16) , montmorillonite (17) and scrim (18) . As will be seen from the drawing and the arrows (19) the layer of baεe (16) overlying the montmorillonite (14) provides a path, between the two layers of montmorillonite (14) and (17) which, becauεe it is designed to vent air can also allow liquid εuch as water to wick out along the path indicated. Thus, the incorporation of a venting base in the sheets (10) and (12) can have undesirable results.

Figure 2 shows how the construction described in European patent application 246 311 (McGROARTY) overcomes these problems. In the MCGROARTY construction a lower sheet (19) has a base (20) and montmorillonite (21) . An overlaid sheet (22) has base (23) and montmorillonite (24) . In McGROARTY the base (20) and (23) are of solid plasticε non-venting and impermeable material. Thus in the construction shown in figure 2 the baεe (23) forms a non- water transmissive layer between the two layers of montmorillonite (21) and (24) thus giving a very good seal. Thiε is a significant advantage over the prior art of figure 1.

Unfortunately, however, the McGROARTY construction doeε have several practical, other difficulties. Firstly, the bases (20) and (23) are made from a thick, impervious and essentially solid plastics material, described in the specification as HDPE.

Further, the specification describes the fact that granules of montmorillonite are adhered not only to the base but also to each other.

Waterproofing materials of thiε kind are uεually εupplied in rolls and have to be unrolled and placed to lie in the pond, lagoon or storage εpace. With the baεe (20) (23) made from high denεity polyethylene the McGROARTY material iε less flexible that when uεing a fabric (non-woven or woven) for the base. This means that the product is much more difficult to handle and the montmorillonite is likely to crack during folding and unfolding. Further, because of the nature of an HDPE plastic sheet the adhering of the montmorillonite to its surface is not eaεy. Quite large quantitieε of very strong glue have to be uεed. As mentioned, in the McGROARTY conεtruction the montmorillonite particleε or granuleε are applied in layerε which are adhered not only to the base but alεo to each other. Thiε makes the product even less flexible and more difficult to handle. Because of the high stiffness of the product McGROARTY has to dispense with any scrim such as the scrim (15) (18) and this means that if any montmorillonite iε loosened due to folding and unfolding it can easily become displaced leaving voids in the montmorillonite layer. The McGROARTY material is also very stiff and difficult to handle.

A further waterproofing barrier material is discloεed in Britiεh patent number 2 202 185 (NAUE) . In the NAUE specification a layer of montmorillonite iε εandwiched between a pair of layers of non-woven textile material, in which two layers are united by needling, the needles passing through the layer of montmorillonite and uniting all three layers. This product again haε diεadvantageε. Firεtly, both the non-woven layers of textile material are essentially gas venting. Therefore, when they are laid they have the εame diεadvantages as the CLEM construction. Further, because the montmorillonite is not adhered to the layers, as the material iε unfolded, folded and manhandled during installation, the montmorillonite can move relative to the two layerε leaving voids and/or more permeable thinner areas in the montmorillonite layer.

There is a further disadvantage in that all these earlier materials tend to use particulate montmorillonite which may be from 2 - 5, uεually about 3mm in εize. Although finer material can be poured to fill gaps between the larger granules, such granules tend to make up the bulk of the montmorillonite layer in the waterproofing material. As the water proofing material iε only relatively thin, for example containing only perhapε one or two layerε of montmorillonite granules, proble ε can ariεe in connection with foreign bodieε in the montmorillonite used. In its natural εtate montmorillonite iε found alongside shale and other impurities. Whilst the montmorillonite can be quite highly purified, it is not unusual for a low percentage of shale particles to remain in the final sized and graded montmorillonite. An unfortunate result of the use of relatively large granules of montmorillonite in the layer is that granules of impurities can also become incorporated in the material. The chemical nature of εhale and εome other impuritieε have the effect that not only are they not montmorillonite (and therefore do not swell upon contact with water) , but, when wetted, act as to inhibit swelling in adjacent montmorillonite granules. Thus, a single granule of shale in a layer of waterproofing material can form a small area (perhaps 10mm in diameter) which does not swell upon being contacted with water. Small εuch areas are generally water impermeable, but medium and larger εuch areas allow water to pasε through the εheet. When water preεεure iε high thiε flow can cause significant waεh out of adjacent montmorillonite leading to failure of the sealing system. Although the percentage of impuritieε iε εmall, and although the failure rate is εmall, when a large area iε εealed uεing sheet material incorporating such impurities it needs only a single leak for the whole system to have failed. A pond or lagoon which has a single leak is no pond or lagoon at all!

Particulate montmorillonite has also been mixed with various organic components to form a thick putty (εee US Patent Number 4 534 925) . Typical componentε are polypropene and polybutene. This material has been extruded in the form of rodε and sheets, usually being stored between layers of release paper. Such material has been used for εealing ground foundations and similar structures. It haε not, however, being extruded εo as to become united with a carrier sheet and be capable of use in large rollε for covering large areas. Indeed, the polypropene and polybutene used iε intended deliberately to give the extruded material a rubbery or formable conεiεtency enabling it to be moulded by hand around small areas such as chimneys, at joints in concrete panels or where drains penetrate foundations. These materials are alεo quite expense and prohibitively so for use in relation to large area sheets.

It iε an object of the present invention to provide a waterproofing material whereby the above described disadvantages are reduced or minimised.

Smectite includeε montmorillonite (dioctahedral) and εaponite (trioctahedral) clay mineralε and their chemical varietieε. They have commercially valuable εwelling and ion-exchange propertieε. The smectites have a layer of lattice structure, but differ from micaε in that the bondε between layers are weakened because of internal chemical εubstitutions. Montmorillonite consiεtε of layerε of negatively charged oxygen (0) atoms within which several types of positively-charged cations are fixed in specific positionε. In a two dimensional schematic diagram of the structure (figure 1) , four layerε of oxygen atoms can be seen to define upper and lower tetrahedral εheets containing tetravalent silicon (Si) and sometimes trivalent cations (3+) of aluminium (Al) and iron (Fe) . The apiceε of the tetrahedra point toward each other and oxygen atomε at the apices form part of the octahedral sheet that may contain trivalent cations (Al, Fe) , divalent cations (Fe, Mg) , both divalent (+2) and trivalent cations, or divalent and monovalent (+1) lithium (Li) cations. The presence of two tetrahedral sheets and one octahedral sheet is the basiε for claεεifying the montmorillonite structure as 2.1 (2x tetrahedral 1 x octahedral sheet structure) . The 2.1 structural units are separated by interlayerε of loosely held hydrated cations. These cations are present to balance the negatively charged structure.

If a particle of Montmorillonite is to expand it needs to take in water into its interlayers. Thiε mechanism is valency dependent. Ionic compounds are formed because a metal atom donates one or two electrons to a non-metal atom (or acid radical group) . For example, in table salt (sodium chloride) , the electron from the higheεt energy level in the εodium atom iε donated to the chlorine atom and they both form ionε a εodium one pluε cation and chloride one minuε anion. The higher the valency the εhorter the bond length the more stable is the montmorillonite, ie calcium two plus cationε will replace εodium one pluε cationε. In order for this replacement to take place the cation muεt get cloεe enough to the montmorillonite substrate, to do this other mechanisms must be considered.

If a particle of montmorillonite is dropped into a beaker of water itε interlayerε take in water, and gradually the clay spreads until eventually it is uniformly distributed. What causes montmorillonite molecules to behave this way? The anεwer depends on the fact that the molecules within the interlayers are in a state of random motion. Although they can move in any direction, the fact that initially (wetting of the particle) there are far more molecules in the immediate vicinity of the interlayers increaεeε the probability of their moving away from each other reεulting in expanεion. This process is diffuεion, and iε defined in this instance aε a movement of moleculeε from a region where they are at a comparatively high concentration (dry) to a region where they are at a lower concentration (hydration) giving a volume increaεe. Diffusion will always proceed whenever such a concentration gradient existε, and it will continue until eventually the moleculeε are uniformally distributed and lattice stabiliεation iε achieved, at which time equilibrium is said to be reached.

Osmosis for the present purpose can be regarded as a special case of diffusion; the diffusion of water from a weaker to a stronger concentration. A weak solution of table salt, for example, will contain relatively less salt and more water than a strong solution of salt. Thus the concentration gradient iε from the weak to the strong εolution. If two εuch solutions were in contact, the water molecules would move one way and the salt molecules the other until both were uniformly distributed (equilibrium) . If, however, the two solutions are separated by a membrane which allows water but not εalt to pass through, only water can diffuse. Such a membrane is said to be selectively permeable or "semi permeable" and the water movement is called osmoεiε, and iε defined in thiε inεtance aε the movement of a εolvent (water) across a selectively permeable interface (membrane) from a weak to a strong concentration of ions in εolution. Montmorillonite interlayers are water selective due to the attraction of dipolar water moleculeε to the highly charged clay particles.

As has been diεcussed above, the montmorillonite clay is made up of a plurality of structural plates each of which has four layerε of oxygen atoms. The outer layer of each plate has a generally tetrahedral format and presents a surface to the interlayer to which cations are looεely bonded. In εodium montmorillonite which is a popular and useful material the cations are εodium ions and are connected to the tetrahedral layers by relatively weak Van Der Waal bonds. The interlayers contain a certain amount of hydrating water molecules. When the montmorillonite is contacted with water more water enters the interlayer, being attracted to the charged cations in the interlayer and moving by diffuεion and capillary reaction εo aε to increaεe the thickneεε of the interlayer. If a body of montmorillonite iε confined between a pair of relatively immobile εurfaceε the pressure within it upon contact with water can become so high such as to prevent any further movement of water into the structure. This build up of a high preεεure layer which cannot abεorb any water makes montmorillonite an excellent water-proofing agent. It is widely used in civil engineering structures.

Often used as a substitute for sodium montmorillonite is calcium montmorillonite wherein the loosely held cations in the interlayer are mainly Ca 2+ rather than Na +. Because of their divalancy the calcium ions bind more εtrongly to the outer tetrahedral layerε than doeε εodium. In uεe calcium bentonite has a property that when initially wetted it will εwell and expand in the εame way as sodium montmorillonite. However, if the material should dry out, for example due to low rain fall or a falling water table calcium montmorillonite cannot shrink back to its original size upon loεε of water without cracking. After cracking and upon re-wetting the interlayer becomeε incapable of absorbing more water and therefore the clay can not re-wet so as to reform the water proof barrier. Thuε, a calcium bentonite water proofing material should only be uεed in caseε where permanent wetness is to be encountered. It iε possible to treat calcium bentonite with a strong sodium containing solution so aε to displace a certain percentage of the calcium ions from the interlayer and replace them with sodium so aε to give the calcium montmorillonite propertieε closer to sodium montmorillonite. However, this material is not as good aε pure εodium montmorillonite, and tendε to εuffer from the same problems as calcium montmorillonite.

All εodium containing montmorilloniteε do have a problem when the water which comeε into contact with them is contaminated by salts, particularly sea water or other εalts which render the ground water ioniεed and highly active. In ground water calcium is invariable present in quantity from soil and minerals. When such ionic calcium comeε into contact with montmorillonite it invariably tends to migrate into the interlayers. Once in the interlayer the double valency of the Ca+ cationε makeε the calcium selectively adhere to the four sideε of the tetredral layerε displacing εodium. Such contamination can quite quickly result in complete stripping of sodium from the interlayer, so converting the montmorillonite from the sodium to the calcium form with the disadvantage which has been outlined above. This particular proceεs makes it generally unwise to use even sodium montmorillonite in a situation where the ground water can become rapidly ionised or contaminated by leachateε or the like. In particular, fertiliεers are a particularly notorious cauεe of ground water ionisation and can cauεe sodium montmorillonite break down. It is an object of the present invention to provide an improved εmectite clay.

In a paper entitled "Preparation of Montmorillonite Polyacrylate Intercalation Compounds and the Water Abεorbing Property" by Ogawa et al published in Clay Science Number 7, 243 251 (1989) , the authors have described the introduction of a acryla ide into montmorillonite and the polymerisation of the acrylamide to form a polyacrylamide intercalation compound. The enhanced water-absorbing propertieε of the compound are noted.

It iε to be appreciated, of courεe, that the processes carried out in the Ogawa paper were esεentially laboratory proceεεeε involving εmall amountε of material. No techniqueε were described for making any useful product and there was not discusεion of the advantages of high density εuch compoundε as waterproofing agents.

The present invention is additionally concerned with smectite liner intercalation complex (herein after referred to as a - ι

"SLIC") materials having improved properties.

Desirably the smectite containing layer is εandwiched between εaid support sheet and a cover sheet.

Reinforcement can be provided in the middle of the smectite containing layer.

The reinforcement can be secured to the cover sheet and/or the support sheet.

The invention also provides a method of making a waterproofing material including mixing particular smectite with at least one other subεtance to form a plastic mass, forming that mass into a layer and uniting it with a support sheet.

The laminate of the smectite layer and the support εheet can be treated after union to cauεe the layer to looεe a degree of plaεticity to enable it to be handled and εtored without undergoing further deformation.

Deεirably the εmectite is mixed primarily with water to form a paεte or a putty like plaεtic maεε which can be extruded rolled or otherwiεe formed into a continuouε layer. - . -

After forming the layer can be subjected to a drying step to remove excess water to convert the smectite layer into a more dimensionally εtable configuration unlikely to deform further during transportation and storage and further to increase the swellability of the smectite upon contact with water in use.

Additives which modify the behaviour the smectite under certain specified conditions such aε salt water, or presence of strong leachates, radiation hydrocarbons or organic chemicals can be added at the mixing stage to be operative when the smectite is in use.

Union of the layer of smectite containing layer with the support sheet can be by adhesive, but desirably no adhesive is used, the mixture of smectite (and other substance(ε) ) being such aε to allow pressure force the plastic mass into the intersticeε of the cover εheet (which iε desirably of a textile nature) phyεically to unite the two. Similar connection can be effected between the layer and the cover εheet.

Inεtead of water, or in addition to water, organic materialε such aε methanol, ethanol and other alcoholε, glycerine, diesel and other oils and fats can be used. Theεe materials do have the advantage that it is not necessary to drive off water εo aε to increase the swellability of the smectite layer, but they also have the disadvantageε that they do need a drying εtep εo that the material is not subject to further deformation under its own weight during storage and transportation and many organic materialε are uεually far more expenεive then water.

Alcoholε, particularly methyl alcohol do, however, have particular advantageε. Whilst alcohols are generally expensive, they are also usually far more volatile than water. Thus, a plaεtic maεε made using methyl alcohol can, after having been formed into a cohesive continuous layer be dried using far less heat than would be necesεary to drive out the water from a similar mass. In addition to this however, the alcohol driven off can be condensed and reused thus offsetting the cost thereof.

The montmorillonite meεh εize can be anything from 50 mesh or smaller, desirably, however the size is a maximum of 100. In practice a mesh size of 200 haε been found useful although variations downwards from about 100 mesh do work although with leεs desirable qualities. Finer esheε are perfectly acceptable, but tend to be unnecessary. The smectite used iε desirably sodium montmorillonite although calcium montmorillonite ( modified by treatment sodium hydroxide) can be used. As the montmorillonite is usually broken down εignificantly during mixing to micro εizeε, initial grain εize iε not critical.

The fabrics used as support and/or cover layer can be conventional woven or non-woven textiles such aε nylon or polypropylene or polyester. They should be non-venting (that is to say they do not allow gas or liquid to paεε along the structure in use to any significant degree) . The fabrics are desirably woven and this degree of non-venting can be achieved by ensuring that the fabric is of relatively open mesh and fairly thin, a significant portion thereof being embedded in and physically uniting with the outer layer of the montmorillonite layer.

The invention includes of course, a waterproofing εheet made by the methods aforeεaid.

The invention also provides apparatus for making a waterproofing material including a conveyor, meanε for feeding a support to the conveyor, meanε for applying a plaεtic smectite-containing mass onto the support, and means for forming said plaεtic masε into a uniform continuous layer.

Means can be provided for sizing the laminate in thickneεε and/or in width.

Deεirably the apparatuε includes means for conditioning the laminate after formation to render it stable in use and storage. Said means can include an oven for evaporating substances, from the laminate. Means for supplying the plastic mass to the conveyor can include one or more nozzles, and/or an extrusion head.

Means can also be provided for εupplying a cover εheet to a εurface of the layer remote from the εupport εheet.

Meanε can alεo be provided for feeding a reinforcement to be embedded within the εmectite containing layer.

Meanε can be provided for uniting εaid reinforcement with one or both of the cover and εupport εheetε; for example by heat εealing.

The invention method also provideε a method of waterproofing a εtructure to prevent ingreεs and/or egresε of aqueouε fluids including the steps of providing a plurality of sheets each in the form of a laminate of a support sheet and a layer of cohesive smectite, formed from a plastic mass, laying the sheetε to cover the surface of εaid article in overlapping relationεhip and protecting εaid εheetε againεt accidental damage in uεe.

The invention further provideε a method of εealing a site including providing at that site apparatuε as aforesaid, transporting smectite and other subεtance(ε) to the εite, making the material of the invention at the εite and laying the material of the invention directly at the site after manufacture. The invention alεo provideε roofing material in the form of a εupport sheet in combination with a layer of swellable εmectite formed from a plastic maεε.

The invention εtill further provides a roof incorporating as part of its water proofing layer, a layer of εwellable smecite clay formed from a plastic masε.

The layer can be part of the material as aforesaid or can be of other convenient construction.

The invention εtill further provides a seal for a pipe or other plumbing fittingε incorporating or consisting of a body formed from a plastic mass of smectite.

The smectite can be in the form of a sealing ring or annulus or can be provided as a continuous length for wrapping around joints. The sealing material can be made by the aforesaid methods of forming a plaεtic maεε and extruding, cutting or moulding therefrom. The smectite can be formed in other ways, for example by dry powder moulding to form a cohesive mass. The sealing material can be provided with a surface layer, for example by having a surrounding sheath of net or like support material. Internal reinforcement can be incorporated if neceεsary and such internal reinforcement can, if desired, be connected to outer support layer(ε) on the body of montmorillonite. The sealing body of montmorillonite can be wholly or partial surrounded by an impermeable or partly permeable sheet. Such sheet can be arranged to allow water to enter therein but not to leave so as to swell the montmorillonite within the sheath and to urge part of the sheath into sealing engagement with its surroundings. Such an arrangement can prevent extrusion of the

The invention provides as a εecond feature thereof a waterproofing material in the form of a body of material formed from a plaεtic maεε, wherein εaid plaεtic mass contains a smectite/liner intercalation complex.

The liner can cloεely bind sodium cations to the outer layers of plates of the smectite structure therefore reducing the possibility of their replacement by calcium cations.

Alternatively the lining can replace the sodium cations leaving a generally neutral face which can abεorb water by capillary action, but which iε generally neutral and therefore does not attract calcium cations.

The liner used will normally be an organic compound compatible with the outer layers of the smectite plateε. Suitable compound can be εugarε such as fructose, glucose, dextrose and the like which have comparable molecular εhapeε and will complex with the tetrahedral layers on the outside of the plate. A further and desired liner iε an acrylate. The material can be added aε the polyacrylate or an acrylation proceεε can be carried out in contact with the clay.

Another possible liner is alkylammonium tri ethyl alkyl ammonium.

The acrylate can have the formula shown in figure 2.

Although the sodium salt of polyacrylate iε εhown other cation

formε can be uεed.

In the εodium cation form the acrylate can replace the εodium cationε which normally coat the outer layerε of the smectite plates.

The acrylate polymer can be doped with various deεirable material to alter variouε propertieε of the clay.

One particular doping agent iε glycerol. The introduction of glycerol can increase the flexibility of the clay so that a length of the clay can be bent easily without breaking.

Methanol can also be introduced as a uεeful material for increasing the flexibility and reducing the εtiffness of the mixture thuε aεεiεting in itε procesεing. The invention further provideε a method of treating a εmectite clay to form a leach-resistant clay including the step of reacting it with a liner capable of complexing with faceε of the clay εtructural plateε adjacent the interlayerε to form a coating which resists replacement of sodium cations.

The liner can be polyacrylate.

The liner can be alkylammonium timetheyl alkylammonium.

The liner can be mixed with the clay as a monomer or in the polymer form and in the firεt caεe can polymeriεe within the clay.

The invention includeε a εmectite clay made by the method aforeεaid.

The invention alεo provideε a εmectite clay having interlayerε provided with an organic liner preventing replacement of εodium cations and capable of absorbing water and εwelling.

A further problem of smectite clay when used as a waterproofing material, is that its function is very dependent on the amount of montmorillonite uεed. For example when a body of a montmorillonite is constrained between two surfaces, such as the concrete of a εtructure and the ground, when contacted by water it swells and forms the aforesaid high pressure layer which prevents ingreεε of water to the εtructure and therefore effectively waterproofε it. To increaεe the waterproofing efficiency of the clay body, larger quantities of montmorillonite can be used. However, higher quantities of montmorillonite mean thicker sheetε of material which are more difficult to handle and which are heavier have more tranεportation costs and are bulky. In sheets which consiεtε principally of particulate montmorillonite there can be significant difficulty in getting a large quantity into a small area. Sheet material uεed for waterproofing in ground εituation or for roofε, wallε and the like tend to have relatively low densities. This is because they are generally made from particulate montmorillonite adhered to a supporting εheet aε of plaεticε material or textile material and εecured thereto by a variety of means ranging from adhesive to needling to sewing or by embedment in a mesh of fibres.

It iε a further object of the preεent invention to provide an improved εmectite waterproofing material.

The invention provideε a εmectite clay waterproofing material having a denεity greater than 1000 kg. m³.

The waterproofing material can be a sheet at least a metre wide and desirably up to four metres wide or more. The invention further provides a waterproofing material including smectite clay in combination with an organic material forming a liner on itε interlayerε and having a denεity greater than 1000 kg m³.

The material can be formed by rolling, extruεion or the like.

Deεirably the material iε extruded.

The invention additionally provides a method of forming a SLIC wherein alcohol is used to facilitate introduction of the liner into the smectite interlayer and to remove exceεε liner.

N.B Introduction and removal εeem contradictory? If excess acrylate is removed, where does it go to?

The alcohol can be methyl alcohol, ethyl alcohol or any higher fluid alcohol.

The invention also provideε a method of forming a SLIC including expoεing the forming complex to suction remove gas whilst reaction is proceeding.

The gas will usually be air but may be air together with by¬ product gas form the reaction.

Desirably the degassed material is subsequently subjected to pressure .

The invention also provides a method of forming a SLIC including expoεing the forming complex to preεεure during reaction to increase the density of the product.

Deεirably the pressure is uεed after a suction treatment which has removed excesε air and poεεible other gases. The pressure step can, therefore, reduce the number of voids in the product as well aε urging the moleculeε of the product cloεer together to enhance the reaction to produce a denεer product.

Deεirably the denεity of the product iε greater than 1000 kilogrammeε per cubic metre.

The preεεure can be applied by extruεion or by passing the forming material through rollers, or by any other convenient meanε.

We have also found that the temperature at which the reaction between the smectite and the liner takes place is important. The invention therefore, further provides a method of forming a SLIC wherein the reaction is constrained to proceed at such a rate as to ensure that the temperature of the forming product varies between 15 and 30°C. Desirably the temperature is maintained in a range from 20 to 25°C. Where the product iε subjected to presεure aε aforeεaid it iε deεirable that the pressure is applied when the temperature is within the rangeε aforeεaid.

A further disadvantage of existing smectite-based waterproofing materials iε that upon exposure to water they tend to swell (this is the very factor which gives them there waterproofing propertieε in that they produce an area of εuch high pressure of additional water can not penetrate) . However, the pressurerise can tend to be very high and, therefore a very significant overlay of either a heavy earth layer (for example one to two metres) or up to 3" or more of concrete are necessary in order that the expansion preεεure of the εmectite cannot cauεe movement or diεplacement of any εtructure.

Accordingly the invention provides, as a further feature a SLIC having a significantly reduced expansion pressure compared with known smectite based waterproofing material.

The expansion presεure can be aε low aε 10mm of concrete aε carried out in the test later defined herein.

As a further feature the invention provides a barrier against aggressive ionic fluid, the barrier being in the form of a constrained layer of a SLIC, wherein interlayers of the smectite have been treated with said liner to form the complex, the interlayer being capable of absorbing water to swell the complex to a barrier presεure and εaid liner preventing ion exchange between said fluid and the smectite.

The fluid will normally be aqueous and can be highly ionised fluid such as leachate or fluid containing fertilizer and the like. However, the barrier can be equally effective against organic fluids or fluids containing organic material, as the smectite interlayerε remain proof against ion exchange with such fluid. Further, it is desirable that the liner be inert in order that its possiblity of reaction with materialε in the fluid is reduced.

The layer needs to be constrained in order that the barrier preεεure can be achieved. THe conεtraint can be a back-fill or overlay of earth or other material or in solid structure an adjacent or surrounding area of concrete or the like can be used.

A further problem with known smectite based waterproofing materialε iε that it haε been very difficult to εecure them to surfaces to be waterproofed. Whilst a flat or gradually εloping εurface can be eaεily waterproofed simply by laying a sheet of the smectite material thereon. When vertical surfaceε (such aε adjacent edges of concrete panels) are to be waterproofed it haε been neceεsary εomehow to attach a smectite based strip thereto. Existing methods uεed have included the proviεion of rebateε into which εtrips of seal material can be pushed and the use of clips or nails. Although nails can be used they tend to be frowned upon aε they pierce a waterproof layer and they can introduce metal ions into the surrounding water which may have a detrimental effect. Because of the generally incohesive nature of clays and their friability, adhesiveε have not been very effective. Some heavy εoaking adheεiveε have been uεed, particularly the type of adheεive uεed in the adherence of εmectite particleε to εheetε. However theεe adheεiveε have a great tendency to inhibit the εwelling propertieε of the clay and to react adversely.

Accordingly the invention provides a method of securing a seal material to a εurface wherein the seal material is a SLIC, compriεing uεe of an adhesive compatible to the liner to cause adhesion.

Where the liner is a polyacrylate the adheεive can be a cyano acrylate adhesive.

Because moleculeε of the liner extend outwardly from the particleε of εmectite they form a very convenient anchor which can become attached to glue moleculeε. Becauεe they themεelves are securely anchored within the interlayer they form adhesion between the entire complex and the structure to which the complex iε to be adhered. Desirably the adhesive uεed is an ephemeral adhesive which will hold the seal material for a sufficient period of time to allow it to be installed and for further structure to be formed adjacent, but will soon degrade to allow water entry so aε to avoid the proviεion of any adhesive film or layer which might allow water seepage past the seal.

The invention further provides a method of making a fluid barrier including forming blocks of a high density SLIC and arranging said blocks in a layer.

The layer can be a wall, a floor or a roof. The blocks can be bonded aε brickε.

A bentonite containing paεte can be uεed aε a lute. The paste can contain a SLIC.

The invention will be described further, by way of example, with reference to the accompanying drawings wherein;

Figures 1 and 2 are croεε εectional view illustrating overlap joints in the prior art and their diεadvantageε;

Figure 3 is a crosε εectional view illuεtrating a preferred waterproofing material of the invention; Figure 4 is an enlarged crosε εectional view illuεtrating a εurface of a preferred material of the invention;

Figure 5 is a schematic view illustrating the apparatus of the invention suitable for carrying out a preferred method of the invention;

Figure 6 iε a plan view of part of the apparatuε of figure 5 and illuεtrating two possible variations;

Figure 7 iε a view εimilar to figure 3 but illustrating a modified material of the invention;

Figure 8 is a view similar to figure 7 but illustrating a still further modified material;

Figure 9 is a view comparable to figure 1, but illustrating an overlap join made using the material of the present invention;

Figure 10 is an enlarged view of the portion ringed at numeral 10 in figure 9.

Figure 11 iε a baεic two dimensional sketch illuεtrating structure of montmorillonite;

Figure 12 is a chemical formula illustrating the εtructure of an acrylate useable in the invention;

Figure 13 is an enlarged view illustrating the structure of montmori1lonite;

Figure 14 is attempted three dimensional representation of montmorillonite after acylation;

Figure 15 is a view similar to figure 4 but illustrating the addition of doping elements; and

Figure 16 is a view similar to figure 5 but illustrating the microscopic effectε of the acrylation.

The preferred waterproofing material (10) of the invention is a laminate consisting of a core layer (11) containing montmorillonite. The core layer (11) is united with a support sheet (12) and iε deεirably but not eεεentially overlaid by a cover εheet (13) .

The essentials of the material (10) of the invention will probably be best apparent from a detailed deεcription of the way it iε made and the apparatus (of the invention) which is used to make it.

Referring, therefore, to figure 5 it will be εeen that a preferred apparatus (14) of the invention comprises a conveyor (15) having an upper run (16) and a lower run (17) entrained about end rollers (18) and (19) . The upper run (16) travelε from left to right in figure 5.

At the upεtream end of run (16) a εupport sheet (20) is fed from a εupply roll (21) by a guide roll (22) εo aε to run on and in synchronism with the conveyor (16) .

The support sheet (20) is a sheet of woven or non-woven textile material (preferably woven) which iε relatively loose weave, being quite porous in a direction transverse to its plane.

The web forming the support sheet can be made of any geotextile material which is suitable for diεpoεal within the ground for long periods. Typical materials for weaving or forming the fabric of the sheet (20) can be polypropylene, polyesterε including nylon, and many other plaεticε materialε alone or in blendε. The material should be sufficiently strong to εupport the compoεite laminate to be formed and can be εimilar to many of the facing εheetε uεed in relation to the prior known materialε diεcussed in the introduction hereto. Polypropylene and cotton mixers can also be uεed. A typical εupport and/or cover εheet can be of a print weave and of a weight 700g per εq.metre.

Downstream of the supply roll is a hopper mixer (23) in which ; 2 -

particulate montmorillonite can be supplied as indicated by the arrow (24) . The particulate montmorillonite can be supplied from a mill or like supply and in the preferred embodiment is of 200 mesh. Finer mesh can be used although great advantages are not obtained. Meshes up to 50 mesh can be used, but at sizes greater then 100 mesh, union between the montmorillonite particles is less effective.

The procesε which takeε place in the hopper mixer (23) can be either a continuous or a batch procesε. Within the hopper mixer (23) a measured quantity of montmorillonite is mixed with a meaεured quantity of one or more other εubεtanceε to produce a fluent maεε. The other εubεtance(ε) can be supplied from a tank or comparable supply (25) . The subεtance(ε) (26) will normally be fluid and when mixed with the montmorillonite will form a εhapable masε. A liquid uεed can be an organic liquid εuch aε glycerine, dieεel oil or comparable oilε or mixes thereof, gels and other plastic or deformable masε-forming subεtances. However, for economy and for eaεe of handling and simplicity the desired subεtance iε water. In the preferred embodiment of method of the invention water is mixed with the montmorillonite there being approximately from 10 to 30% water, desirably about 15 to 20%.

Alternatively or liquid such as alcohol can be uεed. Methyl, ethyl or propyl alcohol can be used. Methyl is preferred. It therefore needs lesε drying power than water. It can be reclaimed and reuεed.

It iε enviεaged that although a fluid will normally be mixed with the montmorillonite to convert it into a fluent body it is posεible that some powdered or other non-fluid material could be used. For example, a sticky powder such aε a εoap or adheεive could be mixed with the montmorillonite to create a pasty plastic deformable mass which could be extruded or spread to form a sheet. However, in view of the likely expenεe of εuch materialε and the difficulty of mixing it is not felt that these will be practical.

The mixture iε, in the preferred embodiment as mentioned pure water. However, where the final product is to have special qualitieε the chemicalε of thoεe εpecial qualitieε can be included in the mixture of water.

In making a typical product in accordance with the invention 5 killogrammeε of montmorillonite were mixed with 0.446 killogrammeε of εodium carboxymethyl celluloεe (CMC) , 2.5 litreε of methanol and 1.8 litreε of water. Both the CMC and the methanol make the mixed and kneaded product more flexible and extrudable. Water can effect this process, but the more water that is used the more heat iε required to drive it out. This meanε added expenεe.

Although the above particular mixtureε have proved suitable many variations can be made.

Methanol alone or water alone can be used, but neither of these is satisfactory.

The material desirably contains a bulking agent, an anti fungicidal preserving agent, to prevent growth of mould in or on the material and deεirably a lubricant to assist in the extrusion process and convey also a degree of flexibility to the plastic masε. CMC is a very desirable subεtance in that it provides all these properties. It has anti fungicidal properties, it iε a lubricant and it makes the product more flexible. It alεo haε the great advantage that upon contact by water, in use, it disεolveε. Thoεe areaε of the outer εurface of the material when firεt contacted by water have the CMC diεεolved out of them leaving micro pores into which more water can penetrate, wash out more CMC and cauεe rapid expansion of the adjacent montmorillonite. This greatly increaseε the rate of

water transfer into the material. A bulking agent which dissolves in water and aids water ingress to the montmorillonite is very desirable. Inεtead of being provided by a single material these propertieε can be provided by other materials. Although many synthetic materials do have these properties, they tend to be expensive and simple plant extracts which are much cheaper are desired. As a bulking agent/lubricant guargu can be uεed or starch. In connection with these two materialε a εeparate preservative such as any conventional anti fungicidal or micro agent would have to be used.

Any convenient liquid alcohol can be used having from 1 to 12 carbon atoms. Above the 12 alcohols tend to be too viscose for use but below that number any convenient alcohol can be used. It is expected, however, that methyl alcohol will be used because of its cheapnesε and eaεy availability. The CC can be in the form of εodium carboxy methyl celluloεe or any other convenient compound thereof. Protection againεt bacterial attack iε important becauεe the bacterial reactions can produce hydro carbons which react with the sodium irons in the clay. This can reduce the εwellability of the clay.

Aε a possible variation a soluble coating can be provided to εurround a body of material of the invention. Thiε can be arranged to degrade over a relatively εhort period of time (εuch aε a week) . Thiε would enable block seals and the like to be installed without becoming greasy and unhandlable due to adverεe weather conditionε, but would not affect the function of material to swell in use after a brief period of time.

The montmorillonite uεed iε deεirably εodium montmorillonite but calcium montmorillonite or treated calcium also be used. As shown the materials are first mixed by means of a mixer (27) and then extruded by εcrewε (28) to an extruεion nozzle (29) . Where the fluid masε iε spread out as a thin layer covering the entire width of the conveyor run (16) .

If the reinforcement is required within the montmorillonite layer in order that it can be laid on steep slopeε without loεε of function it can be desirable to incorporate within the plaεtic maεε a reinforcing layer. This can be done by embedding the reinforcing layer into the masε as it iε being extruded or it iε being εpread out into a layer. The reinforcing layer can be made in the form of a core having briεtleε or comparable formationε extending outwardε which, with the core diεpoεed centrally in the body of montmorillonite extend to the εurface thereof and contact and possibly project through the surface layers. The material of the reinforcement and the εurface layerε can be made εuch that the exposed bristleε can be heat εealed to contact and be εecured to the outer layerε. It iε envisaged that it would be posεible for the montmorillonite mass to be extruded or formed into a pair of εheets and the reinforcement feed between them and to have its briεtles projecting through each of the two part layers of the montmorillonite core and project to the other εurfaceε thereof ! 7 -

and be united with the support/cover sheets.

Although the extrusion of a thin layer of the plastic mass containing montmorillonite is desirable, as it can be 3 or more metres wide, it could well be that a three metre wide extrusion nozzle is either expensive, slow, or requires inordinate amounts of power to be successful. Such a extrusion nozzle (29) is εhown in figure 5 which alεo showε an alternative which will be deεcribed later.

It is expected that the masε will be extruded aε a rod and rolled flat.

Downstream of nozzle (29) the layer (30) of montmorillonite containing plastic maεε is levelled and formed into a uniform uninterrupted layer. Thiε can be achieved by means of an initial doctor blade (31) or more likely, a roller, and subεequent εizing rollerε (32) to (34). The pairs of sizing rolls (32) (33) (34) can effect kneading and levelling of the fluid material and εubεequent εize thickness reductions.

Figure 6 shows one of the rollerε and εhowε the plaεticε material extruded outwardε beyond the edge of the conveyor and being removed by trimming kniveε (36) .

At one of the sets of rollers (32) (33) (34) there is fed a web of cover sheet (37) , from a supply roll (38) . Of course, if roll (31) or (32) and (33) are needed to effect creation of a uniform flat layer of the montmorillonite containing mass, application of the cover sheet can be left until roll (34) . However, this is not desirable aε rollers (32) and (33) are best protected from the plastic montmorillonite layer by the cover sheet (38) .

The subεtance which convert the powdered montmorillonite into a plaεtic fluent mass will need some degree of treatment, for example by evaporation, drying or partial chemical change so aε to ensure that the final material can not deform further in use or in storage. Thiε can be effected by means of a treatment facility indicated by the reference numeral (39) .

When the mixture subεtance iε eεεentially water or an evaporable liquid the treatment facility (39) will be in the form of an oven and will reduce the solvent water content of the montmorillonite containing layer from 20% down to 5% or less. The treatment facility can be in the form of an oven casing (40) to which hot air is supplied at an inlet (41) and leaves via outlet (42) .

After leaving the treatment facility (39) the laminate (40) can be allowed to cool and then be fed to a store roll (44) . A knife or the like can be provided for cutting the laminate aε it leaveε the oven when roll (44) iε full.

Aε diεcuεεed previouεly in relation to the extruεion of the product,the consistency of the plastic/fluent maεε containing montmorillonite can vary widely from almoεt a liquid condition to a εtiff paεte. When water iε uεed, the εtiffer the paεte the better as water has to be expelled by pasεage through the oven. Again, in the case of organic or organic-containing mixture subεtanceε the stiffer the material the leεε later treatment iε necessary to render the final laminate stable and non-deformable during transportation and storage and use. This process will usually involve evaporation comparable to oven drying or a chemical treatment.

As haε previouεly been mentioned the uεe of a very wide extruεion nozzle (29) may not be practical in view of the power required for εuch a device. Inεtead, aε illuεtrated in figure 6 a εmaller extruεion or fluid delivery nozzle (45) can be uεed which can be mounted so as to perform a generally sinuouε path tranεversely of the direction of travel of the run (17) of the belt (15) . Thus, the nozzle (45) can follow a path indicated by the line (46) . By altering the speed of travel of the nozzle and/or the rate of delivery of the fluent material can be assured that sufficient material is applied to the belt to allow a layer of desired thickneεs to be formed throughout the area of the belt without voids, cracks or the like which would be most undeεirable. To this end it is advantageouε if the material can be applied to εome εignificant acceεε and after having been formed into a uniform coherent layer exceεε material extruded sideways is removed by meanε of the trimming knives or the like (36) . Of course, such material can be reclaimed and re-uεed.

It has been mentioned that the support sheet and/or the cover sheet can be of woven or non-woven material. Woven material is preferred but it gives significant εtrength with leεεer weight of materialε. A non-woven material might have advantage, however in that it can form a phyεical union with the montmorillonite containing core (11) . The term core (11) iε uεed even though the cover εheet (13) may not be provided.

Aε beεt seen in figures 4 and 10 the action of the rollers (32) (33) and (34) iε to cauεe the εupport/cover sheets (12) (13) to be partially embedded in surface zones of the plastic maεε of material forming the core (11) whilst the core is in a plastic εtate. There iε no need for any adheεive, which is an expensive and unreliable component.

As the core is treated in the facility (39) either by evaporation or chemically εo as to cause the core to harden there is a physical locking of the^' surface portionε of the core (11) with portions of the fabrics (12) (13) phyεically uniting them to the εurface without the need for adheεive.

Thiε haε two important conεequences. Firstly, because a good portion of the sheets (12) and (13) are embedded within the material of the core, only a εmall portion of the body of the fabric iε expoεed above the εurface. Thuε, in uεe that fabric εurface will be in contact either with anchoring overburden (at leaεt 150mm of overlying material is recommended to protect εuch layers) the underlying earth. The overburden or the earth penetrates the fabric quite easily ( it is a very open fabric and after there is intimate contact between the overburden and the underlying earth) . This again has two important conεequenceε. Firεtly, once the εupport layer (12) (which will normally be in contact with underlying earth) iε intimately connected by the earth ground water enterε contacts the montmorillonite and causes swelling which createε a seal.

It is a further advantage that because of the intimate contact of the underlying εoil or the overburden with the montmorillonite through the support and over sheets (12) , (13) there is no poεεibility that either the cover sheet (12) or the support sheet can allow any venting of gaε laterally though the fabric.

The εecond advantage of thiε iε illuεtrated in figures 9 and 10 which are comparable to figures 1 and 2, but relate to the present invention. In figure 9 a first piece (47) on the material of the invention iε shown overlapping a lower piece (48) , both lying on the ground (49) . The overlap cover εheet (50) of the εecond εheet (48) iε in contact with the εupport sheet (51) on the piece (47) . Aε illustrated in figure 10 the sheetε (50) and (51) are in intimate contact and they are significantly penetrated by montmorillonite from the reεpective coreε of the two panelε. Upon entry of water in the direction of arrow (52) or (53) the montmorillonite in one or each of the cores can swell and expand into the unfilled portions of the fabrics (50) (51) and forming effectively a continuous layer of expanded montmorillonite uniting the two coreε and providing a completely water tight εeal.

Aε mentioned earlier, the invention includeε the waterproofing material itεelf, the method of an apparatus for producing it and a method of waterproofing a structure including the stepε of placing εheetε material of the invention in overlapping relationεhip and placing overburden to protect the εheetε against damage in use.

The invention is not limited to the precise detailε of the foregoing and variationε can be made thereto.

A further diεadvantage of exiεting methodε of waterproofing large εiteε εuch aε pond filled εites, pondε, lagoons and the like is that the material has to be made in bulk in a factory and then transported to the site. The material is manufactured in as wide a width aε possible consistent with manufacturing problems and transpiration. In a εimilar manner the length of the load which can be tranεported iε εtrictly limited. The material may be from a minimum of 4 up to 10 or 20mm or more in thickness , the length of roll which can be tranεported iε not very high. On large εiteε the elimination of large amountε of jointε and the elimination of road transportation can mean significant cost savings.

The apparatus of the invention can be divided into a number of mobile unitε, for example the main conveyor, the mixing hopper and the drying could form three εeparate unit loadε.

It is mentioned earlier, the invention envisageε the use of a material comprising expandable montmorillonite clay into a flat or slightly εlopping roof as the whole or a εignificant part of the water proofing component thereof. The material of the invention iε particularly εuitable for thiε purpoεe aε it can be laid on relatively higher slopes then previously known montmorillonite sheets without them being very expensive. Thuε, in the caεe of a roof which haε εtandε the montmorillonite sheet of the present invention can be laid to extend not only the flat εurface but also upstands to form a water proof layer. The montmorillonite core will normally be laid by several cm of gravel or like material providing a bearing layer protecting the montmorillonite beneath. The montmorillonite uεed with, deεirably, be of the εort which can be allowed to dry out and be rewetted repeatedly aε thiε will often happen to a roof εtructure. As mentioned earlier the invention envisages the use of montmorillonite expandable clay aε εealant in pipeε and other plumbing. The montmorillonite material can be in the form of ringε, annular εtripε or εheets and incorporated in underground drainage or supply pipeε, domeεtic plaεticε or metal pipeε and comparable plumbing inεtallations. The cheapnesε of the montmorillonite meanε that they are ready and cheap εubεtitute for rubber or plaεtic sealing ringε and are cheap enough to be replaced when ever the joint needε to be opened or replaced.

In this case the use of an alcohol or a comparable liquid is advantageous because the oven stages do not have to be as long and as powerful aε is necesεary in the case of driving water from the plastic mass.

When carrying the invention into effect using a SLIC, there can be uεed a polyacrylate aε the liner a quantity of untreated εodium montmorillonite and approximately 10% by weight of a polyacrylate of the formula εhown in figure 2, from 2% to 7% of a εodium carboxymethyl celluloεe (CMC) , 14% of methanol and 5% of glycerol were intimately mixed together. Kneading and mixing were continued until the mixture reached a suitable consistency for extrusion. Thiε can take longer than would normally be necessary for simple mixing aε the chemical reaction between the acrylate and the structural plates of the clay takeε εome time to occur. The heat emitted by εuch reaction iε an important factor in bringing the forming εmectite acrylic complex to a εuitable consiεtency and structure.

Once this has occurred (Its occurrence can be tested by initial trial extrusions. The products of such extrusions, if unacceptable can be returned for recycling) the mixture is pasεed to an extruder where it iε driven towardε an extruεion εcrew, and subjected to a suction stage to remove significantly all entrained gas from it before being extruded in the form of a rope, profile or sheet as desired.

The montmorillonite used in the proceεε iε finely ground and haε the structural formula and shape shown in figures 1 and 3, the cations in the interlayer being esεentially εodium cationε.

During the reaction the clay becomeε acrylated and the long organic chainε of polyacrylate penetrate into the interlayerε and diεplace water. At the particle εurfaces, polyacrylate bonds with strong hydrogen bonds to the free unsatiεfied OH groups. Thiε effectively εhieldε the εodium cationε, thuε greatly reεiεting their replacement by calcium cationε in contaminated ground water.

On the microεcopic scale (which is illuεtrated very schematically in figure 6) a particle of clay consiεtε of a plurality of small structural plateε between which the helical acrylate moleculeε are disposed. The surfaces of the helical acrylate molecules are bonded to the tetrahedra within the faces of the εtructure plateε oppoεite the interlayerε and project beyond the edgeε of the particle. This projection of the acrylate molecules beyond the surface of the particle has a εignificant effect in the abortion of water by the clay. Thus although the acrylate does, to some extent mask the electro-chemical water absorbing propertieε of the clay by effectively neutraliεing the εodium cationε in the interlayer the extending helical polyacrylate molecules extending outwardly from the particleε have a εurface tension effect which draws water towardε the particleε and causes it to enter into the interlayers by capillary action thuε cauεing a εwelling of the particle which is comparable to the electro-chemical swelling which previously occurred but which iε not dependent on the preεence of cationε within the interlayerε.

This has the important effect that any cationε which enter within the interlayer can not replace εodium cationε and thus do not reduce the capacity of the clay to expand, shrink and re-expand after drying out.

Inεtead of carrying out the method of the invention using acrylate other materials can be used. For example sugarε εuch aε fructose, glucoεe,dextroεe can be uεed. All act in very εimilar way to the acrylic molecule and have comparable and similar effects. The use of sugar may, however, be undeεirable - _ '

in εome circumstances in view of its encouragement of microbial growth. Of course, there may well be advantages in this particular property in certain situations.

A further alternative liner material is alkylammonium trimethyl alkyl ammonium which can be used in the manner very εimilar to the polyacrylic compound to give a εimilar complex with εimilar propertieε.

Turning now to the εecond aεpect of the invention reference iε again made to our prior application 9218178.3 and to the aforegoing deεcription. In making a εmectite clay water proofing material in accordance with the εecond aεpect of the invention the method aforesaid is carried out with or without the acrylic material. In the preferred method of this invention εodium montmorillonite powder waε mixed with of polyacrylate glycerol and methanol. The maεε waε mixed together for εome fifteen minutes and then extruded through a 25mm square orifice at a rate of about 0.5 metreε per εecond to produce a rope like concrete εealing εtrip having a denεity of about 1350 kg m m^"3.

The actual denεity can be varied by varying the proportion of materialε in the complex. - "t b -

Of course, the waterproofing material can be made without using the liner such aε polyacrylate. In addition it is posεible to use CNC either in addition to the acrylate or as a subεtitute therefore. The CNC can be useful in varying the reaction rate of the clay but it also has a property of forming, on the surface of the extruded material a layer which improves the life of the εealing material by resisting degradation and swelling by rain over a firεt few hours or dayε.

In teεting the smectite organic complex of the present invention a layer of conventional particulate smectite clay waterproofing sheet was laid on the ground and contacted with typical water high in ionic leaching chemicals. After six hourε the bentonite layer had abεorbed the liquid and had swelled to form a uniform water retaining layer.

A complex according to the invention was similarly treated and had, within six hourε reached preciεely the εame condition.

The two εheetε were then allowed to dry. In the complex clay εheet according to the invention the εheet reduced in thickness to its original thickneεs with no significant cracking. In the untreated prior art clay particulate layer sheet there waε εignificant cracking and large gapε appeared in the material. Both εheetε where then rewetted (whether pure water or contaminated leachate water waε uεed made no difference) . The prior art material, wherein clearly sodium montmorillonite had been converted to calcium montmorillonite there waε no εignificant re-swelling. The cracks remained and water was able to penetrate through thoεe crackε even after prolonged soaking with water as would happen in an underground situation. The prior art material was no longer waterproof and did not itself form a waterproof layer by expansion.

On the contrary, however, the complex montmorillonite clay of the preεent invention formed a uniform waterproofing layer.

In the past it has been posεible to adhere particleε of bentonite to εheetε to form coheεive layerε, but rather large quantitieε of adheεive have

been neceεεary and the bondε which may form with the bentonite have not been particularly εtrong.

With a liner material incorporated within the actual εtructure of the clay itself very strong adhesive bondε can, it haε been found now been made between bodieε of the εmectite complex and εtructureε εuch aε concrete walls, roofs and the like. To obtain εuch a bond it is only necesεary to formulate an adheεive which iε εuitable for attachment to the liner molecules which protrude from the surface of the clay particles or the clay body if it has been extruded or otherwise formed into a sheet rod or the like. In the caεe of the acrylate smectite complexed clay a cyano- acrylic adheεive can be formulated which can adhere the smectite complex clay body to concrete and the like and which can allow the body to expand and contract as it is wetted, dried and re¬ wetted over many cycles.

Further possibilities include the adhesion of a sheet of the clay, either as a cohesive body formed by extrusion or otherwise or in a particular manner to a supporting sheet, for example of high density polyethylene, a geotextile or the like by means of adhesive, needle punching or the like.

Adhesive and/or stitching or penetration by polymer εpikeε weldable to a sheet on the other side of the clay can be used to form a stable slope engaging material.

Aε well as montmorillonite, saponite and other smectites can be uεed.

In carrying out a further preferred process a batch of about 60 kilogrammes was prepared, the figureε given in the following being percentage figures for the various components.

Firstly, 25% water was added to a mixer, followed by 16% sodium polyacrylate. To theεe waε added 5% methyl alcohol. When theεe three had been mixed half of the total bentonite load of 63% was added. Once the mixture had become smooth 1% carboxy methyl celluloε (CMC) and a εmall (about 0.1%) of εodium hexa etaphoεphate waε added. Both these materials were added slowly and after they had been added the mixture was stirred for some while. Thereafter the other half of the bentonite waε added, the mixture kneaded for a εhort time and then paεεed to an extrusion machine wherein it waε first driven towards a perforated plate whence it emerged in vermicelli-like form into a vacuum chamber. In the vacuum chamber air and any other gases such as reaction products and probably some evaporated alcohol are extracted.

The material then falls to the base of the vacuum chamber and is engaged by the rollers of the extruεion machine and driven towardε a 25mm εquare extrusion head having 3mm radius corners. The forming complex (intercalation commenceε in the mixer and i-s εtill continuing aε extruεion takeε place) haε a smooth outer surface and is a coherent flexible and uεeful εeal material for uεe at the junction between the εtructural componentε εuch aε concrete εlabs, panels and where service conduits paεs through foundations and the like.

The percentageε of the variouε materialε uεed can be varied aε follows:-

The alcohol uεed can be methyl alcohol, ethyl alcohol or any other liquid alcohol and εerveε to facilitate introduction of the liner into the εmectite interlayers. Further, εome of the alcohol is, during the heating stage, (the heating iε due to the heat of the reaction which beginε to effect the material towards the end of the reaction period) is expelled and carries with it

excess polyacrylate which can be deposited on the outside of the extruded strip as a shiny layer. This layer may εerve as lubricant as the εtrip passeε through the die and helps to produce a smooth continuous surface. In addition this deposited acrylate also forms a coating for the material which delays the onset of severe water briefly and helps in allowing the material to be installed and perhaps wetted or exposed to the atmosphere before additional material is applied to the surround.

The function of the presεure during extruεion is to increaεe the denεity of the product by eliminating voids which might otherwise form within a less than coherent mass. Thiε, together with the vacuum εtep which haε removed air has the effect of compressing the material to a high density. Thiε moveε the moleculeε εlightly closer together during extrusion thus increaεing the rate of reaction and encouraging the formation of the complex from the intercalated polyacrylate liner.

Deεirably the denεity iε greater than 1,000 kilogrammes per metre cube and a preferred density is over 1,3000 kilogrammes per metre cubic.

The process described above produces a sealing strip very suitable for use in concrete foundations and the like and also in plumbing applications in the sealing of pipes and comparable fittingε. The material can be extruded in many shapes for example square, strip, triangular or in any other convenient form. By rolling or extrusion the material can be formed into sheets which can be used to form an ideal barrier against aggresεive ironiεed fluidε. Such ioniεed fluid will usually be leachetε from plants or sites or may be atmospheric water or ground water contacting the capping of a landfill site. It haε been found that fertiliεer and other materials which may be applied to foliage above a landfill site forms a highly ionised material as aggressive as any leachate and which can seriously damage conventional bentonite liners and capping.

The material made in accordance with the invention above, however, haε the acrylate or other liner εo εecurely attached to the bentonite interlayers that the cation exchange capacity (CEC) of the material is nil or very low. This means that there is no posεiblity of the smectite turning to a calcium form which will not reswell after drying out. Further, as the liner is preferable a plastic material the inherently stable nature of a polymeric plaεticε material makes the possiblity of it being attacked by leachate or strong solutions quite remote.

Instead of being extruded as a strip the material of the invention can be formed into bricks, either on a block making machine into which portions of the forming complex can be introduced and compressed to shape, cr a generally rectangular strip can be extruded and cut as by travelling knives to form blocks. The blocks can be used then to form a barrier by building in the nature of a wall, or by laying them on a floor, or lying them on some support to form a roof for a containment area. The blocks can be bonded aε conventional bricks and a bentonite containing or other paste can be used as a lute in the joints. Desirably a SLIC paste is used as the lute. In a wall a cavity layer can be provided and individually drained in order to allow testing of the integrity of a "front line" layer cf the wall and provide an air gap to prevent transfer of water from one wall to the other by direct contact.

A further advantage of the material of the invention resides in the fact that by appropriate selection of the liner the susceptibility of the material to adherence can be greatly increased. It is often useful to be able to attach a sealing strip to a, for example, vertical surface. This can be at the junction of various concrete components, between concrete panels or the like. In the past this has involved the provision of a recess into which the strip must be pushed (and the recess accordingly rather carefully dimensioned to receive the strip as a push fit) or the strip must be clipped or nailed in position. Whilst the clipping and nailing are effective methods of securing the strip they can be expensive and the provision cf nails in the sealing strip is generally felt to be undesirable as might form a path from leakage, or tney r.iαht introduce metal atmos into a water surrounding them with the possiblity of reducing the waterproofing qualities of the smectite.

Therefore, by selecting the liner to be compatible with a convenient adhesive it is poεεible for a layer of adheεive to be made which will εecure a strip of the material invention to, for example, a vertical surface. In the case of a polyacrylate interliner, the ends of the acrylate molecules protruding from the various particles of smectite form ideal sites for forming an adhesive bond with glue such as cyano acrylate adhesive to give a bond to concrete and comparable surfaces.

The bonding can be by means of spaced portionε of the adhesive spotted at intervals along the line to which the εtrip is to be attached. Desirably, the adhesive used is designed to be an adhesive which will hold the εtrip securely over a maximum period of perhapε three or εix dayε in order to allow the user to carry out all processes in relation to the installation of the seal and the creation of other structures nearby. However, it is importnat that the adhesive thereafter degrades in order to prevent the poεsiblity of a waterproof adhesive film remaining which might provide a water path which could by-pass the seal strip.

As mentioned the material can be extruded as a strip profile or as a wide sheet. When oroducinα a wide sheet it is desirable to extrude the material in the form of a hollow formation and then split that hollow formation to form a sheet. Desirably the material iε extruded in the form of a holly cylinder and then slit and laid flat.

Many other variations are poεεible within the scope of the invention.

Claims

C la ims

1. A water proofing material including a carrier sheet and united therewith a layer containing particulate εmectite clay material formed from a plaεtic maεε.

2. A method aε claimed in claim 1, wherein the smectite containing layer iε sandwiched between said support sheet and a cover sheet.

3. A method aε claimed in claim 1 or 2 , wherein reinforcement is provided in the smectite containing layer.

4. A method as claimed in claim 3 wherein the reinforcement is secured to the cover sheet and/or the support sheet.

5. A method of making a waterproofing material including mixing particulate smectite clay with at least one other substance to form a plastic mass, forming that masε into a layer and uniting it with a support sheet.

6. A method as claimed in claim 5 wherein the smectite layer and the support sheet are treated after union to cause the layer to lose a degree of plasticity to enable it to be handled and stored without undergoing significant deformation.

7. A method aε claimed m claim 5 or 6 wherein the smectite is mixed to form an aqueous plastic mass which can be extruded rolled or otherwise formed into a continuouε layer.

8. A method aε claimed in claim 5 or 6 wherein the smectite is mixed with a non-aqueous or a mixture of aqueous and non- aqueous liquids to form the masε.

9. A method as claimed in claim 7 or 8 wherein after forming the layer is subjected to a drying step to remove liquid from the layer.

10. A method as claimed in any of claims 5 to 9 wherein the smectite containing layer iε united with the εupport sheet by adheεive.

11. A method as claimed in any of claims 5 to 9 wherein the smectite containing layer and the support sheet are physically united.

12. A method aε claimed in claim 8 or 9 wherein appendent to claim 8 wherein an alcohol is used as all or part of the liqui .

13. A method as claimed in claim 12 wherein some of the alcohol is removed and recvcled after conditioninσ of the laminate.

14. A waterproofing material made by the method of any of claims 5 to 13.

15. Apparatus for making a laminate waterproofing material including a conveyor, means for feeding a support to the conveyor, means for creating a plastic smectite containing maεε, means for applying the plastic mass onto the support, and means for forming said plaεtic masε into a uniform- continuous layer.

16. Apparatus as claimed in claim 15, wherein means are provided for εizing the laminate in thickneεs and/or in width.

17. Apparatus as claimed in claim 15 or 16 and including means for conditioning the laminate after formation to render it stable in use and storage.

18. Apparatus aε claimed in claim 17 wherein said means includes an oven for evaporating substances from the laminate.

19. Apparatuε as claimed in claim 18, wehrein means are provided for recovering volatile solvent from said substances and recycling it.

20. Apparatuε as calimed in any of claims 15 to 19 wherein the meanε for supplying the plastic mass to the conveyor includeε one or more nozzles, and/or an extruεion head.

21. Apparatuε aε claimed in any of claimε 15 to 19 wherein means iε provided for supplying a cover sheet to a surface of the layer remote from the support sheet.

22. Waterproofing material made by the method of any of claims 15 to 21.

23. A method of v/aterproofing a εtructure to prevent ingreεε and/or egreεε of aqueous fluids including the εtepε of providing a plurality of εheetε each of material aε claimed in any of claimε 1 to 5, 14 or 22, laying the sheets to cover the εurface of εaid εtructure in overlapping relationεhip and protecting εaid εheets against damage in uεe.

24. A method of sealing a site including providing at that εite apparatus claimed in any of claims 15 to 21, transporting smectite clay and other substance (ε) to the εite, making the material of the invention by the method of any cf claimε 5 to 13 at the εite and laying the material of any of claimε 1 to 5 , 14 or 22 directly at the εite after mnaufacture.

25. Waterproofing material as claimed in any of claims 1 to , 15 to 22 and having a density greater than 1000kg per cubic metre.

26. Waterproofing material as claimed in any of claimε 1 to 4 , 15, 22 and 25 and being at leaεt one metre wide, preferably greater than two metreε wide.

27. Waterproofing material made by forming from a plastic mass containing particulate smecite clay and liquid.

28. Waterproofing material made by forming from a plastic masε containing particulate εmectite clay and liquid, a proportion of εaid liquid having been expelled from the material after forming.

29. Material as claimed in claim 27 or 28 wherein he liquid iε aqueous.

30. Material aε claimed in claimε 27 or 28 wherein the liquid is organic.

31. Material as claimed in claim 27 wherein the liquid iε a mixture of aqueous and organic liquids.

32. Material as claimed in any of claims 27 to 31 and formed by extrusion.

33. Material as claimed in any of claims 27 to 31 and formed by rolling.

34. A method of making a waterproofing material including mixing particulate smectite clay with at leaεt one other εubstance to form a plastic mass and forming that mass.

35. A method as claimed in claim 34 wherein the maεε is treated after union to cause it to lose a degree of plasticity.

36. A method as claimed in claim 34 or 35 wherein the smectite is mixed to form an aqueous plastic maεε.

37. A method aε claimed in claim 34 or 35 wherein the εmectite iε mixed with a non-aqueouε or a mixture of aqueous and non-aqueous liquids to form the maεε.

38. A method as claimed in any of claims 34 to 37 wherein after forming the layer is united with a carrier sheet.-

39. A method aε claimed in any claim 38 wherein the smectite containing layer is united with the εupport εheet by adheεive. - 6 -

40. A method as claimed in claim 38 wherein the smectite containing layer and the εupport sheet are physically united.

41. A method as claimed in claim 37 wherein an alcohol is uεed as all or part of the liquid.

42. A method as claimed in claim 41 wherein εome of the alcohol is removed and recycled after conditioning of the laminate.

43. A waterproofing material made by the method of any of claims 34 to 42.

44. Apparatuε for making a waterproofing material including a conveyor, meanε for creating a plaεtic εmectite containing maεε, meanε for applying the plaεtic mass onto the support, and means for forming said plastic masε into a desired shape.

45. Apparatus aε claimed in claim 44 including meanε for supplying a carrier sheet to the conveyor for union with the maεε.

46. Apparatuε as claimed in claim 44 or 45, wherein meanε are provided for εizing the laminate in thickneεs and/or in width.

47. Apparatus as claimed in any of claims 44 to 46 and including means for conditioning the material after formation to render it stable in uεe and εtorage.

48. Apparatuε aε claimed in claim 47 wherein εaid means includeε an oven for evaporating εubεtanceε from the laminate.

49. Apparatuε aε claimed in claim 47, wehrein meanε are provided for recovering volatile εolvent from εaid substances and recycling it.

50. Apparatuε aε calimed in any of claims 44 to 49 wherein the means for εupplying the plastic maεε to the conveyor includeε one or more nozzleε, and/or an extruεion head.

51. Apparatus as claimed in claim 50, wherein the extruεion head is adapted to extrude a tube and means iε provided to cut the tube and unfold it to form a flat web.

52. Apparatuε as claimed in any of claimε 44 to 51 wherein meanε is provided for supplying a cover sheet to a surface of the layer remote from the support sheet.

53. Waterproofing material made by the apparatuε of any of claimε 44 to 52.

54. Material as claimed in any of claims 27 to 33, 45 or 53 and having a density greater than 1000kg m._?.

55. Material as claimed in any of claims 27 to 33, 45, 53 or 55 and being greater than 1 metre in width, preferably greater than 2 metres.

56. A waterproofing material comprising a plaεtic maεε containing a particulate smectite clay having, at molecular level, structural plates sandwiching interlayers between them, the plates having outer tetredral layers facing the interlayers and an organic liner complexed with said tetrahedral layers.

57. A waterproofing material including a smectite clay having its interlayers provided with organic liner to discourage replacement of sodium ions and being capable of abεorbing water and εwelling.

58. Material as claimed in claim 56 or 57 wherein the liner closely binds sodium cationε to the outer layers of the plates therefore reducing the posεiblity of their replacement by calcium cationε.

59. Material as claimed in claim 56 or 57, wherein the liner replaces sodium cationε leaving a generally neutral face which can absorb water by capillary action, but which being generally neutral, does not attract calcium cationε.

60. Material aε claimed in any of claimε 56 to 59 and being εelected from organic compondε compatible with the outer layerε of the smectite plates and exemplified by sugars; aε fructose; glucose; dextrose; acrylate; polyacrylate; and alkylommonium trimethyl alkyl ammonium.

61. Material aε claimed in claim 60 wherein acrylate used and polymeriseε within the clay.

62. Material as claimed in any of calimε 56 to 61 and contianing glycerol.

63. Material aε claimed in any of claimε 56 to 62 wherein an alcohol iε uεed in the preparation of the complex.

64. A method of treating a εmectite clay including the εtep of reacting it with a liner capable of complexing with faces of the clay structural plates adjacent the interlayers to form a coating which resists replacement of sodium cationε.

65. A method aε claimed in claim 64 wherein the liner iε sleeted from fructose; glucoεe; dextoεe; acrylate; polyacrylate and alkylammonium trimethyl alkyl ammonium.

66. A method as claimed in claim 64 wherein the liner is mixed with the clay as a monomer and polymerises within the clay.

67. A method as claimed in claim 64, 65 or 66 wherein alcohol iε used to facilitate introduction of the liner into the smectite interlayer.

68. A method aε claimed in any of claims 64 to 67 including exposing the forming complex to suction remove gas whilst reaction is proceeding.

69. A method as claimed in any of claims 64 to 65 wherein the degassed material is εubsequently εubjected to pressure.

70. A method as claimed in any of claims 64 to 68 wherein the forming complex iε εubjected preεεure during reaction to increaεe the denεity of the product.

71. A method aε claimed in any of calims 64 to 68 wherein the reaction between clay and liner is constrained to proceed at εuch a rate aε to ensure that the temperature of the forming product varies between 15 and 30°C.

72. A method as claimed in any of claimε 71 wherein the temperature range is from 20 to 26^UC.

73. A method as claimed in claims 71 or 72 wherein presεure is applied when the temperature is within the range εpecified.

74. A material made by the method of any of claimε 64 to 73.

75. A material aε claimed in any of claimε 56 to 74 and having a density greater than 1000 kg. m°.

76. A material as claimed in any of claims 56 to 63, 74 and 75 and being a sheet at leaεt a metre wide and deεirably at leaεt two metreε wide.

77. A material as claimed in any of claims 56 to 63, 74 to 76, and having a significantly reduced expanεion preεεure compared with known smectite based waterproofing materialε.

78. A material aε claimed in claim 77 wherein the expanεion pressure is below 15mm of concrete as carried out in the test defined herein.

79. A material as claimed in calim 78 wherein the expansion pressure iε belov.^* 10mm of concrete aε carried out in the teεt defined herein.

80. A barrier against aggressive ionic fluid, in the form of a constrained layer of a material aε claimed in any of claims 56 to 53 and 74 to 79.

81. A barrier as calimed in claim 80 wherein the constraint is back-fill or overlay of material or solid εtructure.

82. Material as claimed in any of claims 56 to 63, 74 to 79 secured to a surface by use of an adhesive compatible to the liner.

83. Material as claimed in claim 83 wherein the liner is a polyacrylate the adhesive is a cyano acrylate adhesive.

84. A method of making a fluid barrier including forming blocks of material as claimed in any of claims 56 to 63 and 74 to 79 and arranging εaid blcαkε in a layer.

85. A method aε claimed in claim 84 wherein the layer iε selected from a wall, a floor and a roof.

86. A method as claimed in claim 85 wherein the blocks are bonded.

87. A method as claimed in claim 84, 85 or 86 wherein a smectite-containing paste iε used as a lute.

88. A method as claimed in any of claims 84 to 87, wherein the paste is a SLIC.

89. Sealing material in the form of material as claimed in any of claims 56 to 63, 74 to 79.

90. Sealing material as claimed in claim 88 and being in annular form.

91. Waterproofing material subεtantially as described with reference to the accompanying drawingε.

92. A method of making a waterproofing material εubεtantially aε deεcribed with reference to the accompanying drawingε.