AU2001235286A1

AU2001235286A1 - Method for stabilizing irregular structures

Info

Publication number: AU2001235286A1
Application number: AU2001235286A
Authority: AU
Inventors: Scott Macpherson
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-03-03
Filing date: 2001-02-23
Publication date: 2001-11-22
Anticipated expiration: 2021-02-23

Description

Method for Stabilizing Irregular Structures

Field of the Invention This invention relates to a method for stabilizing irregular structures such as rock structures in mines as well as other rock, concrete and molding tool structures. The invention also relates to weather resistant and anti-corrosive polyurea coating materials for stabilizing irregular structures.

Background of the Invention

Membrane coatings have been developed for the purpose of partially replacing the screen component of bolts-and-screen or thin shotcrete layers in mines. Such coatings are used primarily in underground hard rock mines for the provision of rapidly-deployable area support coverage. One such coating material Mineguard^{I M}, described in PCT/CA91 /00223, is a polyurethane polymer coating which forms a conventional plastic membrane on selected surfaces. Other types of polyurethane coatings that form thin membranes on certain surfaces are described in U.S. Patents 4,748,201, 4,748,192 and 4,738,989.

While some of these aforementioned types of polyurethane coatings have been used for stabilization of rock structures in mining, these coatings are thin and provide only limited support and strength to certain structures. Such coatings don't adequately fill cracks, crevices and fractured ground without repeated time- consuming and expensive applications. Furthermore, these polyurethane coatings are also conventionally applied to form a thin membrane cover and do not have widespread applications in other fields.

There has not been provided an effective rapid method using a particular polyurea or polyurethane type coating material that can effectively produce a cohesive coating material which acts to stabilize rock and concrete structures or other irregular structures as well as provide durability, weatherability and anti -corrosion properties to the structure. Furthennore, there is presently no polyurea or polyurethane type mesh or film coating that provides the necessary characteristics to effectively stabilize various irregular structures and that has general use in the field of mining, construction and composite parts manufacturing. There is therefore a need to develop a simple, rapid and cost efficient method for stabilizing irregular structures such as rock and concrete stnictures that obviates at least some of the shortcomings of the prior art.

Summary of the Invention

The present invention relates to a fast reacting method of making a polyurea coating material for stabilizing irregular structures and the polyurea coatings so prepared. The method and the polyurea coating materials have widespread use in the stabilization of irregular structures such as irregular rock, concrete and molding tool structures.

In accordance with an aspect of the present invention is a novel method for stabilizing irregular rock, concrete and molding tool surfaces and structures in general. The method of the present invention is simple to use and effectively provides in one aspect a cohesive unwoven type fabric that can be applied to uneven and irregular surfaces to create a consolidating and stabilizing mesh or webbing type of membrane. As such, the method provides a fibrous weather resistant and anti- corrosion type mesh that has the ability to bridge large gaps and cracks in irregular structures especially rock and concrete structures. The fibrous mesh can w ithstand large fluctuations in temperature and precipitation with minimal deterioration or effect on its stabilizing properties on the applied underlying structures.

In the first aspect, the method is preferably used to provide a fibrous mesh that acts to effectively, rapidly and safely stabilize rock structures particularly in hard rock mining. The fibrous mesh can effectively fill large gaps in various rock and tunnel structures. The method can also be used to stabilize rocky hillsides adjacent highways to prevent falling rocks and rock slides. The method also has general use in the construction industry in order to stabilize any type of concrete or concrete/rock structure.

The method of the present inv ention in this aspect, allow s for air and w ater permeation therethrough when the material is applied as a mesh or webbing. In another aspect of the present invention, the method can be altered to provide a plastic film type of polyurea coating which is impermeable to w ater and air In this aspect, the plastic film coating has application in the field o l^" mold too l i ng especially for making molds and the like. In a further aspect of the inv ention, the method can provide for a more matted geotextile type mesh product that has use the landscaping and road building trades

In yet still a further aspect, the method can provide a "jelly" state that is useful as an adhesive With respect to any aspects of the invention, the resultant polyurea material piovided as a fibrous mesh, matted mesh, plastic film oi jelh state can be provided as a layered oi multi layered stmctuie incoipoiating the v arious toimats of polyurea material

According to an aspect of the present invention is a polyurea spi av sv stem for providing a stabilizing polyurea matenal According to a further aspect of the present invention is a polv ea spray system for providing a stabilizing polvurea fibrous mesh matenal

Accoidmg to still a furthei aspect of the present in ention is a polv ui ea spi av system foi prov iding a stabilizing polvurea plastic film matenal

According to vet a furthei aspect of the piesent invention is a poh uiea spiay system for providing a stabilizing polvurea geotextile matted material

According to another aspect of the present invention is a polyurea spray system for providing a stabilizing polyurea foam material

According to still another aspect of the present invention is a polyurea spray system for piovid g a stabilizing polvurea jelly matenal According to an aspect of the piesent invention is a method toi stabilizing irregulai rock, concrete and molding tool stiuctuies the method comprising concurrentlv heating and mixing a mixture ot polyowpi opv leι diamii with an aromatic diam e liquid, mechanically purging the mixture under pi essui e v ith an isocv an ate - applying the purged mixture to a desired irregular stiucture

According to an aspect of the piesent invention there is a method foi stabilizing irregular lock and conciete strut tuies, the method comprising concurrenth heating and mixing m about a 2 1 to 1 1 ratio a mixture of polyoxypropylene diamme with an aromatic diamme liquid, mechanically purging the mixture under pressure with an lsocyanate to create a fibious mesh, the mesh being applied to a desired irregulai rock and concrete structure Preferably, the mixture is heated from about 90°F to about 1 15°F and purged under pressure from about 1000 psi to about 3500 psi In this manner, optima! fiber sizes and lengths are accomplished to enmesh fill in gaps between and stabilize irregular rock and concrete structures. According to another aspect of the present invention is a method for stabilizing irregular rock, concrete and molding tool structures, the method comprising: concurrently heating and mixing about a 2:1 to 1 :1 ratio, a mixture of polyoxypropylene diamine with an aromatic diamme liquid; - mechanically purging the mixture at over about 1000 to 3500 psi with an isocyanate to create a plastic film, the plastic film being applied to a desired megular stracture.

Preferably in this aspect, the mixture is heated from about 140°F to 1 7()°F In this manner, under the appropπate high pressure the irregular rock, concrete or molding tool surfaces are stabilized within a plastic film type of coating which is impermeable to air and water. In accordance with this aspect, other materials can be added to the purged mixture to alter the final plastic polyurea film material. Such materials include but are not limited to fire-retardants, ceramic microspheres, rubber crumbs and the like. According to another aspect of the present invention is a cohesive polyurea mesh for use m consolidating and stabilizing irregular rock, concrete and molding tool structures.

According to a further aspect of the present invention is a fibrous polyurea mesh for stabilizing and supporting irregular rock and concrete structures, the mesh comprising: elongate fibers comprising a mixture of polyoxypropylene diamine and aromatic liquid diamine; said fibers having a high tensile strength: and said fibers bemg weather resistant and anticonOsive. According to still a further embodiment of the invention is a cohesive fibrous mesh compnsmg strands of inorganic polymers for stabilizing irregular surfaces. According to yet a further embodiment of the invention is a cohesive fibrous mesh comprising flame retardant strands of inorganic polymers and additionally compnsmg a flame retardant.

Preferably, the mesh is made of a polyurea material which when dry provides a durable, damage resistant, hard protective surface which is moisture resistant, has a high tensile strength and is non-flammable.

According to another aspect of the present invention is a polyurea geotextile mat for use in consolidating and stabilizing irregular rock, concrete, and dirt surfaces.

According to another aspect of the present invention is a polyurea plastic film for use m stabilizing molds and molding tool structures.

According to another aspect of the present invention is a polyurea foam for use m consolidating and stabilizing irregular rock, concrete, moldmg tool and dirt surfaces and other composite structures and manufactured parts.

Bnef Descnption of the Drawings

A detailed descnption of the preferred embodiments are provided herein below with reference to the following drawings in which-

Figure 1A is a photograph of rocks stabilized in accordance with the method of the present invention, Figure IB is a closer view of the photograph of Figure 1 A,

Figure 2 is a photograph showing the fibrous natuie of the stabilizing coating as formed by the method of the present invention,

Figures 3A through 3E are photographs showing how the method of the present invention is applied to stabilize adjacent, but separate rock structures

In the drawings, preferred embodiments of the invention are illustrated by way of example. It is to be expressly understood that the description and drawings are only for the purpose of illustration and as an aid to understanding, and ai e not intended as a definition of the limits of the in ention

Detailed Descnption of the Preferred Embodiments

The invention is a fast reacting method of making a polyurea matenal and the polyurea materials so prepared The method and the polyurea materials ha e widespread use in the stabilization of irregular surfaces and structures such as irregular rock, concrete and molding tool stnictures.

The method of the present invention provides in a first preferred embodiment a cohesive unwoven weather resistant mesh that is applied to irregular and uneven surfaces and acts to stabilize such surfaces and as such has use in the mining industry.

In accordance with the method of the present invention, a polyoxypropylenediamine and an aromatic diamine liquid is sprayed in a ratio of about 2:1 to 1 : 1 (v/v) with a prepolymer MDI isocyanante through a heated urethane proportioner. A ratio of about 1 :1 is most preferred. The aromatic diamine liquid is susceptible to temperature fluctuations. Thus at higher temperatures the resultant polyurea material is less structured and more "plastic" liquid for wetting out. This mixture is then processed with an impingement mixing spray gun at a suitable pressure of about 1000 psi to about 3500 psi using mechanical purge and without a spray tip design. A pressure of about 2000-2500 psi is preferred. Suitable spray guns for use in the method are the Gusmer D ^ΓM gun or the Intergun GG^{I M} gun. The resultant product is a fibrous sticky mesh when dispensed at a suitable temperature of about 90°F to about 1 15°F, most preferably about 110°F.

The MDI (methylene diparaphenylene isocyanate) isocyanate acts as a catalyst and can be for example but not limited to diphenyl methane 4,4' - di isocyanate. The functionality of the isocyanate may vary as is understood by one of skill in the art. The aromatic diamine for use in the method of the invention may be a variety of such compounds which provide the necessary fluidity properties to the resultant purged material as is well understood by one skilled in the art. Representative examples of suitable aromatic diamines for use in the invention include but are not limited to di(methylthio) toluene amine and diethyl toluene diamine.

The fibrous spray projects from the spray gun approximately 8 to 10 feet when dispensed at approximately 2000 psi. The fibrous mesh takes approximately one minute to dry from a sticky mesh to a hard finish depending on the external environmental conditions. The fibrous spray is advantageous in that it does not essentially drip from ceilings as it is being applied but instead "sticks" or "adheres" to the surface to which it is being applied.

Such a fibrous mesh can be sprayed onto irregular rock structures in order to stabilize them. This is shown in Figures 1A and IB. In these Figures, rocks are shown embedded within the mesh. Figure 2 illustrates the fibrous mesh like characteristics of the resultant product. Figures 3 A through F. show how the method of the present invention is used to stabilize two rocks which arc spaced about 2 inches apart. Figure 3E in particular, shows that the rocks can be completely enmeshed with the coating material. All of these Figures demonstrate that the fibrous mesh effectively fills the voids and gaps between separate rock structures holding such structures in place. This effectively stabilizes such structures so that they do not fall apart or cave in. As such, the method has particular use in the mining industry to stabilize tunnels and create a safer working environment. The fibrous mesh can also be sprayed onto a selected surface to create a matlike appearance resembling a geotextile used in the landscaping and road building trades. The fibers can be sprayed to accumulate and be built up to any desired thickness on any surface. The fibers can even be sprayed on to dirt surfaces or to fill cracks up to about 6 inches wide. In another aspect of the present method, the mixture of polyoxypropylenediamine and aromatic diamine liquid is sprayed in about from 2. 1 to 1 :1 ratio with a prepolymer MDI isocyanante at a temperature of about 140°F to 170°F and then purged at pressures of about 1000 to 3500 psi, with 2500 psi being most prefened, in order to have the fibers become liquid and wet out to fonn a plastic film. In this aspect, a ratio of polymers of 1 : 1 is most preferred along with a temperature of about 145°F to 150°F.

In this embodiment of the invention, several different types of materials can be added to the purging mixture such as for example fire retardants, ceramic microspheres, rubber tire crumbs, fibrous and/or particulate-type material. Materials, which can be employed, include a wide variety of fibers, and more particularly glass fibers, such as chopped or woven glass fibers. The glass fibers may be chopped into short fibers by a chopper above or adjacent the exit nozzle of the spray equipment, so that the chopped glass falls onto the reaction mixture exiting from the nozzle tip of the spraying equipment. In addition, particulate materials may be employed, as well as other additive materials, such as pigment dyes, carbon particles, carbon fibers, synthetic fibers, natural fibers and various other additives as well as combinations thereof. For example, a machine can be used to fog particles of a fire retardant matenal into the path of the liquid spray Suitable fire retardant materials include for example, particles of chemically altered grafite (GrafGuard manufactiued by

UCAR Carbon Company Inc ) One skilled in the art would ieadily comprehend the type of fire retardant materials that can be used the method of the present invention

This composite when exposed to about 160-170°F explodes to form a carbon strand about 100 times its original volume creating an mtumescent fire proof shell to protect.

The liquid spray may be loaded with about 0.25 kg Grafguard™ per square meter at lmm thickness As modified to provide a fluid plastic film, the resultant plastic film is air and liquid impermeable and has been demonstrated to have a class A frame spread of 20 with a smoke generation of 40 (E84 Sterner Tunnel Flame Spread Test).

It is prefened that the method of the present invention be used to stabilize rock structures in mining and in particular, underground mining The method can be used as a substitute for the conventional liquid thin sprayed membranes or order to effectively adjoin and secure adjacent rocks to create a self supporting arch even m the presence of gaps and holes This helps to pi event cav e-ins Howevei , it is understood by those skilled in the art that method of the present invention can be used to stabilize any type of irregular rock or concrete type structure whether it be indoors or outdoors The method also has use to stabilize and enforce secondary containment dikes around storage tanks and spill areas As such, the method has v alue foi hazardous containment work The method of the present mv ention also has use in the general construction industry as well as potentially m sewer manhole rehabilitation as well as in landscaping, ornamental pond construction and road building

As a plastic film coating, the coating can be applied in mold making as it cures very quickly and the resultant hardened product is very durable compound to other molded coatings and fiberglass In this aspect, the liquid coating is sprayed as a skin onto a waxed model to facilitate its release therefrom Supports or "strong-backs" may be used and placed foi stiffening along the encased mold The fiber mesh type material is then spiaved to lock on the supports ci eatmg a tough and durable mold tool As a film coating it mav be used in conjunction w ith othei open mold sin laces or even a gel coat molds, such as a polyestei gel coat oi aci v he molds

In v et a furthei embodiment oi the inv ention the method can b<_ pi un-cd bv spraying the mixture of polv oxv pi opv lenediamirc ana ji omaiiL l ι-μ κl ι about from 2 1 to I T ratio with a prepolymer MDI isocyanante at a temperature of about 110°F to 130°F, most preferably 130°F, and then purged at pressures of about

1000 to 3500 psi in order to create a "jelly-like" matenal that is useful in the construction industry Such a "jelly-like" matenal can be used as an adhesive in the construction industry as it has been found to cure and harden in seconds thus setting any type of brace or similar matenal embedded therein.

As a plastic film coating, a water stream may be introduced as a fine mist, atomized, to mix thoroughly with the chemicals as they are purged and create a foam of fine bubbles. Such foam may be used as an open mold or as a medium for fillers, fibers and other structural enhancements A combination of the plastic film and foam forms a tough composite having widespread use in the molding industry.

One skilled m the art will recognize that the method of the invention may be practiced to provide for a multilayered type of coating or reinforcement material that may compnse vaπous layers of a plastic film, fibrous mesh, matted mesh and foam. In summary, the present invention provides a rapid and easy method for providing a durable and weather resistant mesh or plastic film coating that provides good strength and support of irregular structures such as rock, concrete and molding tool structures. The resultant product, whether provided as a fibrous mesh, a matted mesh, plastic film or foam has anti-conosion and chemical resistance. Furthennore, flame-retardant matenals as known to those skilled in the art can be introduced into the liquid type polyurea material oi as a layer on top of the finished product m order to provide for the non-flammable properties

Although prefened embodiments hav e been described heiem in detail it is understood by those skilled in the art that variations may be made thereto w ithout departing from the scope of the invention

Claims

1. N method for stabilizing irregular rock, concrete and molding tool stnictures, the method comprising: - concunently heating and mixing a mixture of polyoxypropylene diamine with an aromatic diamine liquid in about a 2:1 to 1 :1 ratio; mechanically purging the mixture under pressure with an isocyanate; applying the purged mixture to a desired iπegular structure.

2. The method of claim 1 , wherein said mixture is heated at a temperature of about 90°F to 1 15°F and mechanically purging said mixture at a pressure at about 1000-2500 psi to create a fibrous mesh.

3. The method of claim 2, wherein said mixture is heated at a temperature oi^' about 100°C and mechanically purged at a pressure of about 2000 to 2500 psi to create a fibrous mesh.

4. The method of claim 1, wherein said mixture is heated at a temperature o\^" about 140°F to 170°F and mechanically purged at a pressure of about 1000 to 3500 psi to create a plastic film.

5. The method of claim 1, wherein said mixture is heated at a temperature of about 110°F to 130°F and mechanically purged at a pressure of about 1000 to 3500 psi to create an adhesive jelly.

6. The method of claim 4 additionally comprising the step of adding a fine mist of water to the mechanically purged mixture to create a foam.

7. The method of claim 1, wherein said isocyanate is a methylene diparaphenylene isocyanate.

8. The method of claim 7. wherein said methylene diparaphenylene isocyanate is diphenyl methane 4,4^" diisocyanate. - t l -

9 The method ot claim 4. additionally comprising the step of adding a material to the purged mixture, said matenal being selected from the gioup consisting of fire retardants ceramic microspheres, rubber tire crumbs, glass fibers, pigment dyes, carbon particles, carbon fibers, synthetic fibers and natural fibeis

10 The method of claim 9, wherein said fne retardant is chemically altered grafite.

1 1 A polyurea fibrous mesh for stabilizing and supporting megular structures, the mesh compnsmg;

- elongate fibeis compnsmg a mixture of polyoxypropylene diamme, aromatic liquid diamme and isocyanate, wherein said fibers have a high tensile strength and are anticorcosive and weather resistant.

12. A polyurea material produced by the method of claim 1.