US3676198A

US3676198A - Method for waterproofing structures

Info

Publication number: US3676198A
Application number: US36296A
Authority: US
Inventors: Bryan M Mcgroarty
Original assignee: BRYAN M MCGROARTY; WESLEY R GREEN
Current assignee: BRYAN M MCGROARTY; WESLEY R GREEN
Priority date: 1970-05-11
Filing date: 1970-05-11
Publication date: 1972-07-11
Anticipated expiration: 1989-07-11

Abstract

APPLYING GRANULAR NON-HYDRATED BENTONITE TO SURFACES TO BE WATERPROOFED BY MIXING IT WITH A MATERIAL CAUSING THE GRANULAR BENTONITE TO ADHERE TO THE SURFACE. UPON BEING WETTED BY WATER, THE BENTONITE WILL EXPAND TO SEAL THE SURFACE FOR AN INDEFINITE PERIOD.

Description

July 11, 1972 B. M. M GROARTY 3,676,198

METHOD FOR WATERPROOFING STRUCTURES Filed May 11 1970 United States Patent Oflice 3,676,198 Patented July 11, 1972 US. Cl. 117-1055 28 Claims ABSTRACT OF THE DISCLOSURE Applying granular non-hydrated bentonite to surfaces to be waterproofed by mixing it with a material causing the granular bentonite to adhere to the surface. Upon being wetted by water, the bentonite will expand to seal the surface for an indefinite period.

CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of my copending application Ser. No. 751,517, filed Aug. 9, 1968, now abandoned for Method and Material for Waterproofing Structures.

BACKGROUND- OF THE INVENTION (1) Field of the invention The present invention relates to waterproofing processes and in particular processes for applying non-hydrated granular bentonite to surfaces.

(2) Prior art Waterproofing characteristics of granular bentonite have long been known. However, the applying of the bentonite to surfaces, in particular vertical walls, has been really difiicult. For years just the bentonite was applied in a paste or butter with a trowel, or was poured between a sheet of plywood and a vertical wall. American Colloid Company developed Volclay panels which are much like cardboard panels and are stapled or fas tened to the wall to be waterproofed. A good deal of hand work is necessary with these panels, the panels are quite expensive, and have certain limitations that prevent ready, economical application to basement walls for homes or apartments in particular. These panels are described in Pat. No. 3,186,896.

SUMMARY OF THE INVENTION The present invention relates to a process whereby granular bentonite can be applied with a gun to surfaces, and will remain active to waterproof the surfaces for years. The bentonite is carried in an air suspension and discharged from a conduit. After the suspension leaves the conduit, the binder is sprayed into and mixed with the bentonite. The concept involves the use of a binder material which will not destroy the swelling properties of the granular bentonite and in certain instances which will break down after the passage of time after the vertical wall has been backfilled, so that the granular bentonite remains in a layer to waterproof a building. The binder does not inhibit the waterproofing characteristics.

The concept includes the use of a binder material which will adequately disperse between the granules of the bentonite and the surface as the bentonite is carried by air toward the surface to cause the mixture to initially adhere in a layer on the wall. Mixing also occurs as the materials contact the surface. The binder material does not substantially react with the bentonite to permanently and adversely affect swelling characteristics. The binder has a long storage life, and is economical to produce with standard materials. Upon the drying out of the bentonite layer during dry weather the bentonite will separate into small segments, or more or less will present a craze drying pattern which prevents opening of large cracks in the bentonite layer. The large cracks have previously been a problem with bentonite layers.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a schematic showing of apparatus utilized with the process of the present invention;

FIG. 2 is an enlarged sectional View showing the position of discharge nozzles used in the application of the coating material used in the present invention; and

FIG. 3 is a block diagram of the process showing the steps of application and the action of the binder solution.

DESCRIPTION OF THE PREFERRED EMBODIMENT Application of a waterproofing layer of the present invention is carried out with very simple apparatus as shown schematically in the drawing.

A hopper 10 is filled with the granular bentonite, which will be described in detail as the description proceeds, and this hopper has a manual regulator valve 10A leading to a rotary air lock valve 11 leading into chamber 12. The chamber 12 receives air from a blower 13 which has sufficient air flow to pick up material dropping through valve 11 to carry it along. The valve =11 is rotated continuously during operation with a motor 16. The flow of air carries the granular bentonite in an air suspension as it exits from the chamber at the exit end 14 and into a hose 15. The valve 10A regulates the amount of material coming from hopper 10. If desired, the rate of rotation of valve 11 can be adjusted using a variable speed drive of suitable design. The bentonite then passes through the hose. A hose end portion 20 forms an exit orifice for the air-particle suspension. The tube is of sufficient diameter to handle the flow of air and bentonite passing therethrough. At the nozzle there is an atomizing nozzle 21 located below the outer nozzle 20. Atomizing nozzle 21 carries a binder liquid under pressure from a source of this liquid under pressure indicated at 22.

The source 2 2 for the binder is a tank that is pressurized with air, and the air pressure in turn forces the liquid through a liquid line 25. The air pressure comes from a source 26 through a regulator 27 to the top of the binder tank 22. A valve 28 can be used for controlling the liquid flowing through the line 27A.

The air atomizing nozzle 21 is of usual or preferred ,design and is shown schematically. The liquid line 25 passes through the center of the nozzle, and air comes through an air line 30, and enters the nozzle 21. As the air and liquid are expended, they form an atomized to coarse spray fan exiting from the nozzle. As shown, the nozzle is attached to the hose end portion 20, and any suitable means can be used for doing this. The nozzle 21 is positioned so that the axis of the nozzle is at an angle of approximately 1530 with respect to the axis of the hose end portion 20. This overlaps the liquid spray with the dry bentonite-air suspension. The fan of material 31 showing the suspended bentonite granules, expands slightly as it comes out of the end of the hose, and the spray fan from the nozzle 21 expands substantially. As shown, the nozzles are positioned so that the liquid spray fan covers a slightly greater vertical width (in cross section) than the sprayed bentonite, when the nozzles are positioned properly, approximately 14 inches from the face of the wall to be coated. The fans are circular, so the spray fan from nozzle 21 is slightly larger in diameter than the spray fan from tube end 20. It can also be seen that the distance from the nozzle 21 to the lower edge 32 of the bentonite-air suspension 31 is less than the distance of the nozzle 21 from the upper part of the spray fan. This means that the concentration of the liquid binder material coming through the liquid line onto the wall will be greater at the lower side of the spray fan. As shown by the lines, the liquid actually sprays outside the bentonite spray to coat the wall with liquid binder before the binder-bentonite mixture contacts the wall. The process includes the use of this type of a spray fan (wetting the wall as the fan moves down) and then moving the nozzle end downwardly during the spraying opera tion, as shown by the arrows on Wall 23. This insures that the wall will first receive only binder and also a greater concentration of the binder in the sprayed material adjacent the wall than in the outer portions of the layer. By moving the nozzle down, the bentonite illustrated at 31 will be built up onto the wall as the nozzle is moved down, and the rate of movement of the nozzle determines the build up of the bentonite. There is a greater concentration of binder material adjacent to the wall than there is at the outer portions of the layer.

This process also helps in sealing the lower joints between the foundations or footings and the lower part of the basement wall. The bentonite on the outer portions of the layers will tend to fall off as it is being applied and build up a small bank of material illustrated at 33 adjacent the junction between the wall and its footings, or the junction between the wall and the ground to insure that waterproofing occurs here. This joint has been one of the trouble spots in waterproofing, and now this is taken care of automatically by the unique positioning of the spray fan with respect to the bentonite spray and the method of application of this material.

The complete wall surface is coated, and the wall 23 is backfilled. The dirt on the outside of the bentonitebinder layer 24 will hold the bentonite in place after decomposition of the binder. The binder holds the layer in place before the binder decomposes.

The granular bentonite used is a unique material known as Wyoming type bentonite (sodium montmorillonite). This material is presently kell known and has a tremendous expansion once it contacts water. The bentonite, which is sold under the trademark Volclay by American Colloid Company carries strong negative charges and in the presence of certain electrolytes, the negative charges are neutralized causing the particles to flock together. After this ion exchange, the bentonite will lose its swelling properties. This means that if it is used in the presence of an electrolyte, either acid, a base or a salt formed in reactions between strong acids and strong bases, its swelling properties can be destroyed. If fairly pure water contacts it, it can swell and then shrink to its original size upon drying out, and re-swell virtually indefinitely.

Therefore, one of the problems in applying bentonite is finding a binder which will not destroy the swelling properties of the bentonite; which will cause the particles to adequately stick together after it is in place even on a vertical wall, and also a binder which will not totally coat the bentonite in a permanent manner. A complete, permanent coating on the particles of bentonite means that water cannot penetrate the coating and no swelling will occur.

One key to being able to apply a coating of granular bentonite and a binder is proper binder material. The present invention discloses such a binder material, and also discloses the inventive concept of utilizing a binder material which will remain active (sticky) so that the excavation around a vertical wall can be backfilled, when desired by the contractor (preferably before substantial rainfall). After backfilling the binder will in time disintegrate. The layer of bentonite against the wall can swell when wet, contract when dry, and still be ready to swell again when it again comes in contact with water.

Another feature is that the binder material, once it has become ineffective as a binder, forms inert lattices of waste products that cause small fault lines in the coating so that upon drying the bentonite layer will craze into a multitude of small cracks rather than drying out and causing one great big crack to open in the layer along the wall. The big cracks cannot be rescaled when water once again contacts the bentonite. By having a plurality of small cracks in the layer of bentonite, when water contacts it, it merely turns to a jell as it normally does in contact with water, and the jell fills these cracks immediately so that there will be no water seepage through the wall.

A third form of binder, an asphalt type, also is sprayed on and inter-mixed with a bentonite-air suspension before and as the materials contact the surface to be coated, this binder does not decompose as readily as the others. Nevertheless, the bentonite particles are trapped in a lattice work of binder and held in place. The asphalt will stick to the surface or wall and also hold the bentonite in place. There are openings in the asphalt that permit water to contact the bentonite and swell for waterproofing.

In all examples shown herein, type KWK bentonite was used, sold by American Colloid Company, Skokie, Ill. This is a pellet form with sizes between 20 and 70 mesh with less than 1% finer than 100 mesh. This means the materials are free of fines to prevent excessive dust during application. The granules of bentonite can vary in size to suit existing conditions.

The process for applying bentonite to a surface to be waterproofed thus comprises suspending bentonite in air and directing the suspension onto the surface to be waterproofed, and intermixing the bentonite and air suspension with a liquid binder material at a sufficient ratio of binder material to bentonite to cause the bentonite to adhere in a layer on the surface to be waterproofed. The step of spraying the binder material to form a binder lattice work throughout the layer of bentonite is also included. Further, the process is characterized in that the intermixing of the bentonite and air suspension with the binder material is performed as the air-bentonite suspension is moving toward the surface.

Stated another way, the process includes the steps of directing a suspension of bentonite and air toward the surface, and prior to the time the bentonite contacts the surface, mixing the bentonite particles with a binder material. The mixing, as shown in FIG. 2, takes place after the bentonite-air suspension leaves the conduit carrying the suspension. The binder is sprayed into the bentoniteair suspension.

Binder Example 1 A liquid binder was formed for use here in the following proportions. For one-hundred pounds of finished liquid hinder, the following quantities were used:

Percent by weight Preferred Maximum Minnnum range rallgo Basic component: Water carried neutral adhesive (selected from carbohydrates) l0 12l5 10-80 Preferred additives:

Ammonia. 1. 5 1. 5-2 1. 52 Ethyl aleoh 8 8-1 8-1 Glycerin... 5 5-. 6 5-3 Yeast (bakers and brewers optional) 1 oz. (/25 cake ea.) Water Balance by Weight to 20%) The preferred ratio application gives a dry layer of bentonite applied to the outside of the wall and means that the binder does not 'wet the bentonite material substantially, but rather caused the bentonite to cluster together into larger clumps and also to stick to the vertical wall. The application procedure and positioning of the nozzles for the binder material and the bentonite aid in this sticking action. The bentonite-binder layer was built up to substantially inch thickness. This is approximately 1 /2 pounds of bentonite per square foot. Layer thicknesses up to 1 inch are applied for heavy service, where there is a great deal of water. The water carried carbohydrates (soluble or which form colloidal suspension in water) are preferably the group consisting of sugars and starches, with dextrins being the most preferred form of starch, and give stickiness to the mixture for initial application. The yeast promotes the fermentation process which will break down the preferred dextrins or sugars (or mixtures thereof) into alcohol as time passes. After the breakdown is complete, the bacteria will eventually die leaving residues between the bentonite particles which remain dispersed between the particles. These residues comprising waste products from the fermentation process and dead bacteria bodies, are neutral substances. Neutral, as used here, means that the substances are neither strong acids nor bases nor any dior tri-valent salts and will not form acids or bases when contacted by water. This insures that the action of the bentonite will not be impaired by the residues left between the particles as time passes. It should be remembered that acids and bases can convert the bentonite to non-swelling type bentonite (kaolin).

If greater percentages of sugars or dextrins are used, the binder components have to be broken down before the layer does an effective job of waterproofing. With higher amounts of sugars or dextrins, the sugars or dextrins will coat the bentonite completely so water cannot contact the particles. Once the sugars or dextrins are broken down, then the waterproofing is again obtained.

The ammonia is in the solution to prevent too much swelling of the bentonite during application. This is because the ammonia is a strong base and limits the ability of the bentonite to expand or swell from the water in the binder. The ammonia also controls the pH of the solution to insure that there isnt an excessive reaction 'which will permanently inhibit the bentonites waterproofing characteristics. The diluted ammonia is present at all places where the water in the binder is contacting bentonite and inhibits the swelling of the bentonite during application. The ammonia is a volatile liquid inhibitor and other volatile inhibitors such as monoethanol amine, diethanol amine, morpholine, dipropylamine, and di-isopropyl amine will work. These inhibitors will evaporate at normal outdoor temperatures in the construction season. The ethyl alcohol is used as a bacteriostat to inhibit the bacteria action while the binder is in the storage tank.

The neutral particles between the bentonite particles are dispersed throughout the layer covering the wall and give fault lines through the layer of bentonite so that the bentonite layer when it dries out, after swelling, will craze (form lots of small cracks) rather than form large fissures or cracks through the layer. The glycerin is a softening agent in the binder solution to insure that the preferred dextrins or sugars will not completely harden as the water used in the solution evaporates but will remain slightly soft and sticky to permit backfilling. When a 12% solution of the binder material is used (the preferred range) the applied layer of binder and bentonite will be ready to expand if water contacts it after the wall is backfilled. The prime consideration is that the dispersion of the adhesive particles is not sufficiently great to prevent the entrance of water into the bentonite material. As greater concentration of active binder materials are used, this ability to initially operate as a waterproofing layer immediately after application is reduced, but still present to a certain degree. The binder is viscous when applied, and

the viscosity of the mixture also retards swelling of the bentonite during application because the viscous material cant easily penetrate the bentonite particles.

The breakdown of the preferred dextrins or sugars by the yeasts into alcohol is relatively rapid, and takes place over a period of approximately 3 to 6 months. Of course, the neutral materials left will not in any way alfect the bentonite laeyrs, and the bentonite particles will be available at once to expand when contacted by water. When heavier concentrations of the carbohydrates are used, they will form crusts around some of the particles of bentonite, but this will break down fairly rapidly when the yeasts are also added. The breakdown by bacteria will take place naturally from soil (anaerobic) bacteria, even without yeast added to the solution, but the yeasts do promote this bacterial action which insures that the applied layer will be ready for service more quickly.

Basement walls waterproofed in the above manner were backfilled immediately upon completion of adding a inch thick layer to the wall and used in the summer of average rainfall in Minnesota. The wall showed no signs of leakage after such use.

The use of dextrins has been found to be the best or most .preferable material for use in this binder.

Binder Example 2 The following components were used for a binder in a liquid suspension:

Percent by weight Most; Preferred Maximum Water Balance by weight (up to 2 cake brewers yeast, cake bakers yeast.

The biodegradable anionic soap can be soaps such as Ivory flakes sold by Procter & Gamble Company, or can be some biodegradable anionic detergent. This material is used to dilute the emulsion and to act as a stabilizer for the emulsified latex.

The polymer constituent is listed in percentages of solids in the final binder. For example, an anionic latex emulsion of a copolymer of butadiene/styrene in a ratio of 70:30 (butadiene monomers to styrene monomers) sold under the trademark Pliopave L Latex by The Goodyear Tire & Rubber Company is a preferred form of the polymer component. This material is sold as a 70% emulsion, which means that the solids content is approximately 70% of the purchased product which is a water emulsion. The percentages listed in the above table are the actual solids content, and not the percentage of the emulsion mixture as it is sold.

Latex is used herein as meaning stable aqueous dispersions of synthetic rubbers or vinyl polymers prepared by the emulsion polymerization process.

The polymer component or constituent of the binder, when it is used, is selected from the class consisting of water soluble polymers of vinyl; emulsified latexes (anionic) of polymers of vinyl (vinyls considered broadly so as to include emulsified polyethylene and polypropylene which are sometimes classed as polyolefines); and anionic latex emulsions of pliable copolymers of butadiene. The most desired polymer constituent of the binder material consists of an anionic emulsified latex of flexible or pliable copolymers of butadiene and styrene. A specific example is the Pliopave L170, which is an anionic stabilized latex of butadiene/ styrene having a ratio of substantially 70:30, with the butadiene monomers forming the primary portion. These are to give resiliency to the material, and are termed elastomeric latexes which means that they are stretchy and not hard. The most preferred ratio was the 70:30.

Emulsified polyethylene sold by Morton Chemical Company worked as a binder in the same solution, but this material is not as stretchy as the butadiene/styrene latex. Also the polyethylene takes longer to deteriorate.

In addition, polyvinyl alcohol, in water solution, can be utilized in the same preferred range of percentages with satisfactory results. In the use of the water soluble polyvinyl alcohol, the dispersing or suspending agent is not necessary, but the dispersing agent is helpful from the standpoint of preventing the water molecules from uniting with the bentonite because it increases the viscosity of the binder. The suspending agent thickens the water and prevents the water from entering the bentonite particles readily. The combined solids content of the active binder material (defined as the polymers and carbohydrates together) should always be a minimum of Thus, where no carbohydrates are used, the polymers should be up to about 10%.

The preferred suspending and thickening agent is cellulose gum, and relates to sodium carboxymethylcellulose of low salt content and high viscosity which is the most preferred material. The term cellulose gum is to include hydroxyethylcellulose which acts as a thickening agent as well, but is more expensive than the sodium carboxymethylcellulose, which is an adequate dispersant. The term cellulose gum will be used to cover these two constituents. The term suspending agents also includes pectins or gelatins that thicken the water and make it viscous.

The higher percentages of the polymers (and the higher percentages of carbohydrates which are the adhesive ingredients or binding ingredients in Example 1) are used where the wall will be left exposed for a long time. Where backfilling is immediate, the lower percentages of the polymers or carbohydrates are desired because of reduction of costs, and because the lower percentages do not cause an enveloping of the bentonite particles which may inhibit the waterproofing characteristics until the binder materials have been removed by natural or implanted bacteria action.

The butadiene/styrene anionic latex is now used primarily in bituminous surfacing. The percentages listed are for the polymers. The carbohydrates (sugars or dextrins are preferred) in binder Example 2 are used as before to provide stickiness for initial contact, and the yeasts are used to provide bacteria growth for breaking down the carbohydrates and the latex after application. The ammonia (volatile inhibitor as defined before) is used as a stabilizer for the emulsion as well and prevents excessive swelling of the bentonite as it is being applied. The ammonia initially reacts with the bentonite to prevent initial swelling as the layer is applied (it is a strong base). Once the water and ammonia (volatile inhibitor) evaporate, the bentonite layer will expand when further water contacts it.

The sodium carboxymethylcellulose (CMC) is preferred as a suspending agent for the low density emulsion of latex. Sodium carboxymethylcellulose is available from Hercules Powder Company, and type 7H has been found to be very satisfactory in this solution. These are commonly called Hercules Cellulose Gums. The cellulose gum is mixed with the binder by suspending the gum in methyl alcohol and then mixing it with the water used for the binder. The CMC is a polymer which gives plasticity and stabilization to the binder. It helps in dispersing the latex throughout the solution.

The cellulose gums have high viscosity, low salt content and a high degree of polymerization. After the bentonite and binder material is in place on the wall, the long molecules of the preferred cellulose gums will be dispersed throughout the bentonite layer. Shortly after installation, when the outer surfaces of the bentonite layer get wet, the cellulose gum molecules will disperse in the layer of water at the surface, and as the molecules disperse they carry particles of bentonite with them so that the small particles of bentonite are in the water film. The outer layer of bentonite will form a jell quickly, mainly because the cellulose gum will disperse in this Water film and carry the bentonite with it. This forms a fuzzy edge along the surface of the bentonite comprising dispersed cellulose gum and bentonite particles. The particles of bentonite that are dispersed in the film of water along the surface of the bentonite will travel with the water if cracks are present in the bentonite layer (water will tend to seep or fiow into such cracks) and these small particles will seal the cracks as the water tends to enter them. The carboxymethylcellulose will travel with the water and the bentonite particles will stay in the crack and it, of course, swells to seal the crack. This gives enhanced initial sealing characteristics over a layer which used only dextrins or sugar in the binder. The cellulose gum will also be destroyed by the bacteria action in approximately three months under wet conditions, but during this time the cellulose gum will have acted to seal many of the small cracks that normally appear in the bentonite layer so that the entire sheet of bentonite is then fairly well scaled up and fissures and cracks that are formed will now follow along where the latex lattice work is formed and where the old cellulose gum molecules were (they will have been destroyed) and where the dextrins or sugar was so that these form a multitude of fault lines. When the bentonite again dries out it cracks in minute cracks and then when it is again wet it will seal these minute cracks quickly.

The substances that are degradable in these solutions is an interlying factor that makes both types of binders work. The end products after being degraded or broken down by the bacteria have to be non-harming to the bentonite. This means they cannot be strong alkali or strong acid, nor can they form acids or bases when contacted by water. The bacteria bodies (the bacteria die) are neutral, organic residue that cause a fault line in between the bentonite particles. They are not strong alkali and strong base so that they will not destroy the swelling properties of the bentonite. Cellulose gum is important because it has binding or adhesive characteristics and will disperse throughout the applied layer as it is applied to help in the binding along with the latex or main polymer mixture, and also help the binding action of the dextrins or sugars that are added. The cellulose gum permits the dispersion of clay particles into any water along the face of the applied layer of bentonite, initially. The cellulose gum also thickens the water carrier to a point where it helps in keeping the latex or other polymer in suspension in the very dilute concentrations used for the binders. During application and as long as water from the binder is present in the layer applied (when the layer is first placed on the wall) the cellulose gum prevents the water from entering the bentonite particles to cause it to swell. The thickening action of the cellulose gum does this. With no swelling of the bentonite when it is applied, there is greater stability to the coating because it will not dry out later to form cracks and start to crumble.

The ratio of the liquid binder (with polymer content) to bentonite is approximately 166 pounds of the binder and about 540 pounds of bentonite. The amounts can be varied from ratios of about 1:6 to 1:2 by weight with binder materials containing the polymers. (Bentonite forms the greater part of the ratio.) The application will go approximately /8 inch thick to one inch thick. Where special problems are incurred such as a lot of water, or water with high mineral content, a thicker layer of the bentonite will be applied. This is because if the water is extremely hard and has free metal ions, it will combine with the bentonite and form the non-swelling type of bentonite called kaolin.

The mixture of the anionic emulsified latex with the preferred sugars or dextrins (carbohydrates) makes the latex soft but sticky so that it will not firm up when it is in final form. This also helps to stabilize the emulsion of latex after it has been diluted with the water solution and also helps keep the latex from de-emulsification. In other words, it keeps it dispersed throughout the complete solution without flocking or coagulating.

When the second binder solution and the bentonite are sprayed on, the binder will again disperse throughout the bentonite particles and the latex will join together with other latex particles to form a very thin open lattice work of latex. This lattice work is three dimensional. This lattice work is formed by contact of the anionic latex solution with the negatively charged bentonite particles. As the anionic latex solution touches the bentonite particles the latex is neutralized; the latex de-emulsifies immediately as free latex. This free latex (fine strands of latex) cannot penetrate the bentonite particles and cause any swelling, but forms a lattice work in three dimensional configurations throughout the bentonite particles giving a rubbery structure holding the particles together as well as the sticky dextrins and sugars holding them together. The lattice work, of course, is extremely thin and light and does not interfere with passage of water through the lattice work, but does act to hold the bentonite particles together. The percentage of bentonite particles affected by the reaction is low so the waterproofing is not adversely affected. The action is not a substantial affecting of properties of the bentonite. The fact that the latex becomes free latex immediately upon contacting the bentonite assures that this lattice work will be formed right on the wall surface.

The latex will break down and disintegrate (decompose) under soil bacterial action or the implanted action of the yeasts. In addition to forming a lattice work for holding the bentonite particles together, the latex gives initial water resistance because of its rubbery consistency in the voids in the barrier of bentonite so that it has the added advantage in the early stages of enhancing the waterproofing characteristics of the bentonite. The spraying of liquid only on the surface of the wall (see FIG. 2) plugs voids in the walls with the latex in the binder to help waterproofing.

Binder Example 3 in emulsion by weight Preferred Maximum range range Components:

Asphalt emulsion type SS-lh Emulsifier agent (resin type) Optional additives: Anionic latex The balance of the binder is water.

Type SS-lh asphalt is a standard type designated in the Specification Series No. 2 (SS-2) of the Asphalt Institute, 1966 Edition, page 9. This type of asphalt is a slow setting asphalt that has a furol viscosity at 77 F. sec. rated at 20 to 100. An actual amount from 18 minimum to a maximum of 110 is found.

The asphalt is emulsified preferably with a resin type emulsifier such as vinsol resin. Other resin type emulsifiers can be utilized to give a hard asphalt when it is broken out of the emulsion. The vinsol resin or other resin type emulsifier helps to prevent sagging when the binder is applied. Vinsol resin is used as an emulsifier in asphalt for a hard asphalt in the final stage.

The asphalt mix, which weighs slightly more than 8 pounds to the gallon, is then sprayed on as previously described through a spraying nozzle 21 from the binder tank into the air entrained bentonite suspension at the rate of 10 to 30% of the asphalt emulsion (asphalt-rubber emulsion when latex is added), including the water base,

with respect to the bentonite. The rate in volume is approximately one gallon of asphaltic emulsion to 80 pounds of bentonite (which would be the 10% representation) up to a preferred rate of substantially 3 gallons of asphaltic emulsion to 80 pounds of bentonite. The preferred application is about 160 pounds of asphalt binder material to 540 pounds of bentonite.

The 'bentonite'asphalt material is sprayed onto surfaces to a layer thickness of about /8 of an inch up to 1 inch in normal application. Thicker layers, of course, can be used. The bentonite is evenly dispersed throughout the layer from the wall surface outwardly to the outer surface of the applied layer. A inch thick layer uses about 1.5 pounds of bentonite to a square foot of surface.

The emulsion looks like a very thin, watery, smooth textured syrup, and is light brown in color at room temperatures. The emulsifier agent contacts the bentonite particles, and as with binder (2), immediately upon contact with the bentonite and application to the wall, the emulsion breaks down. With binder (3), the asphalt solids form a network or lattice work of material between the bentonite particles. The emulsion here has a higher percentage of solids than binder (2) and is applied at about the same pound rate of emulsion in relation to the bentonite used. This means that there is a heavier lattice work of asphalt than the latex binder. The bentonite is trapped in pockets formed in the asphalt and then is held in place. Most of the water in the emulsion also is trapped and kept separate from the bentonite. The amount of water from the emulsion in contact with any bentonite is quite low, and this is adsorbed on the bentonite molecules and also is slightly absorbed. The absorption is not sufficient to hydrate the bentonite. The major portion of the bentonite is unaffected from the emulsion base water and will be free to absorb any external water that contacts the particular layer on the surface being coated. The bentonite layer swells in the presence of water for sealing as before, and therefore forms a waterproof barrier which is a well-known property of bentonite.

The spraying process can be utilized with an asphalt emulsion that has an anionic emulsifier and a water base so that water spraying of the bentonite can be done without causing excessive swelling of the bentonite during spraying. The anionic emulsifier reacts with the bentonite to cause the emulsion to break down so that the asphalt solids join together to form a supporting lattice work for holding the bentonite in place, just as the previous latex base did. Fissure or fault lines are formed by the asphalt between the bentonite particles when the bentonite is in place to prevent clumping together of the bentonite. The asphalt is more affected by temperature, in initial spraying, and therefore the addition of the small amount of latex rubber to the asphalt emulsion as a preferred additive gives the asphalt greater resistance to sagging during extremely hot weather. The latex also gives flexibility to the lattice work of asphalt at all temperatures, thus giving the ability to withstand the shock from backfilling. The asphalt emulsion without any latex added will permit holding material onto the wall in colder temperatures.

The proper ratio of asphalt in the sprayed emulsion gives a sufficient amount of solid binder material to hold the bentonite in place and still keep the initial swelling of the bentonite down so that the bentonite will stay in place even after the sprayed on layer has dried. A lattice work of the asphalt is formed throughout the bentonite particles and the majority of the particles are either completely unaffected by the water base of the emulsion, or only slightly affected, and when the bentonite layer dries the asphalt will still hold the material on the wall without having it flake or fall off the wall. The asphalt lattice work also deteriorates with passage of time leaving an inert residue causing fault lines in the layer where water can enter and thus avoid a formation of large cracks.

The optional latex utilized in the emulsion of binder (3) is :butadiene/styrene anionic latex, for example the 1 1 Goodyear Pliopa've L170 as previously described in binder (2).

The spraying process is used with all binders. The binders make it possible to take the bentonite, which is an extremely expandable material in the presence of water, and spray it on a surface. The Pliopave latex is added to the asphalt emulsion in a blending process, for example that described in the Goodyear Chemical Division Bulletin relating to Pliopave, identified as Methods Bulletin, PP-Z.

Again the method of application is to mix the liquid anionic asphalt emulsion type SS-lh into bentonite carried in an air suspension from an air nozzle discharging bentonite, so that the binder material mixes with the bentonite prior to the time that it is in suspension. This is after the bentonite leaves the nozzle and while it travels to the surface or wall to be coated, and also right on the surface being coated. The asphalt goes out of its emulsion when it contacts the bentonite to form an asphalt lattice interspersed with particles of bentonite. The particles of bentonite are largely unaffected by the reaction with the asphalt. The asphalt will adhere to the wall and support the bentonite particles in place so that when the layer contacts water the particles of bentonite will swell to form a waterproof barrier.

Two of the binder materials, binder material Example 2 and binder material Example 3, are anionic emulsions. In particular, the asphalt binder material is a slow setting anionic emulsified asphalt that will go out of emulsion as soon as it contacts the bentonite causing an immediate lattice work of asphalt solids to be formed. It the binder emulsion is cationic the emulsion should be at a critical state so that as the emulsion contacts the bentonite a small amount of absorption of water will cause the emulsion to break down immediately, causing the solids to go out of emulsion and form the supporting 3 dimension lattice structure for holding the bentonite in place. The anionic emulsion is preferred because of the ease of demulsification of the binder Without excessive destruction of the swelling properties of the bentonite which takes place when a cationic asphalt emulsion is utilized.

Thus in the spraying process it is necessary to have a binder material that does not cause hydration of the bentonite during application. The binder must also not inhibit the ability of the bentonite to later swell in the presence of water. With the asphaltic and polymer type binders, in binder Examples 2 and 3, this problem does not occur because the binder material itself forms a lattice work that will give sufficient support for the bentonite until the wall is backfilled.

Further, the asphalt emulsion 3 breaks so rapidly upon contact with the bentonite that much of the emulsifying water is trapped in pockets formed in the asphalt and later evaporates without expanding the bentonite. The bentonite particles are held in the asphalt lattice work in their original physical shape and chemical constituency. The bentonite exhibits no shrinkage in the applied layer upon drying. The bentonite particles are elfectively isolated from the water used in the asphalt emulsion.

After the walls have been backfilled to hold the bentonite layer in place, there is no concern over the breaking down of the latex or asphalt binder, although if it does not break down, it is not of any concern either because it aids in waterproofing.

Variations in the amount of the bentonite used in relation to the binder can be made, but the binder should be dispersed throughout the bentonite layer to insure that the particles will be held together. The concept is to have a binder which will initially hold bentonite particles together so that it can be sprayed onto the wall and will adhere thereto, without damaging the water absorption properties of the bentonite (cant chemically react with the bentonite) and also which may disintegrate as time goes on. The binder provides small fault lines in a lattice network in the bentonite layer to insure that as the bentonite dries it will not form a great big wide channel crack, but rather a plurality of smaller cracks throughout the coating. Once water again contacts the bentonite layer, the bentonite will swell to quickly fill these smaller cracks and prevent leakage through the Wall that has been waterproofed. There can be no swelling of the bentonite during application, or when the layer dries it would fall 01f. Thus, the suspending and thickening agents plus the ammonia (inhibitors) are helpful.

The binder constituent in the binder material then must be dispersable in water, have adhesive or binding qualities, must not cause the sodium montmorillonite (bentonite) to swell, and which may decompose into neutral substances after application. The property of elasticity is desirable.

What is claimed is:

1. A process for applying bentonite to a surface to be Waterproofed comprising suspending dry bentonite in an air stream and directing the bentonite and air stream suspension onto the surface to be waterproofed, intermixing said bentonite and air stream suspension with a separate spra of liquid binder material which does not substantially affect the swelling properties of the bentonite at a suflicient ratio of binder material to bentonite to cause the bentonite to adhere in a layer on the surface to be waterproofed.

2. The process of claim 1 further characterized in that the binder material contains a carbohydrate binder which adheres to the bentonite particles and to the surface.

3. The process of claim 2 further characterized in that the binder material includes water as a carrier for the binder material.

4. The process of claim 1 including the step of spraying the binder material to form a resilient binder lattice work throughout the layer of bentonite as it is applied to the surface.

5. The process of claim 1 is further characterized in that the intermixing of the bentonite and air suspension with said binder material is performed at least partially as the bentonite-air suspension is being moved toward the surface in the atmosphere.

6. The process of claim 5 characterized in that said binder material comprises water mixed with active binder components which initially bind the bentonite particles together and which deteriorate in the presence of bacteria into substances neutral to the bentonite.

7. The process as specified in claim 6 further characterized in that the active binder components comprise material selected from the group consisting of carbohydrates which are water soluble or which form colloidal suspension in water.

8. The process of claim 6 wherein said active binder components include between 3% to 50% by weight, of material selected from the group consisting of water soluble polymers of vinyls, anionic emulsified polymers of vinyl and anionic emulsified pliable copolymers of butadiene.

9. The process as specified in claim 8 wherein said active binder components include said polymers and copolymers in the range of 3.5% to 6% by weight.

10. The process as specified in claim 8 wherein said active binder material includes 3.5% to 6% by weight of an anionic emulsified latex of a pliable butadiene/styrene copolymer.

11. The binder material of claim 6 wherein said active binder component comprises an anionic pliable latex of a butadiene/styrene copolymer in the range of 3.5 to 6% solids by weight; 1.5% sodium carboxymethylcellulose having low salt content, high molecular weight and high viscosity, an additive selected from the group consisting of dextrins or sugars or mixtures thereof in the range of 6% to 8% by weight, up to 2% by weight of a volatile inhibitor which is water soluble and inhibits swelling of bentonite particles where it contacts such particles.

12. The process of claim 1 wherein the active binder components comprise:

Percent by weight Water soluble or suspendable neutral, degradable adhesives selected from carbohydrates 1 -80 Volatile inhibitors 1.5-2 Ethyl alcohol .8-1 Glycerin .5-3 Water Balance Cellulose gum .7-2 Dextrins or sugars 0-15 Biodegradable anionic soap .8-5

and the balance is water, with a minimum of by weight of the latex or dextrins or sugars or mixtures thereof.

16. The process of claim 6 wherein the binder components consist of:

Percent by weight Water soluble or water emulsifiable anionic polymers of vinyl or flexible latexes of copolymers of butadiene 3.5-6 Cellulose gum 1.5 Dextrins or sugars 6-8 Volatile inhibitors .5-1 Biodegradable anionic soap .8-1

with the balance being the water carrier.

17. The process for spraying bentonite onto a surface to form a layer of bentonite on the surface comprising the steps of:

directing a suspension of substantially unhydrated particles of sodium montmorillonite bentonite and air in a stream toward the surface;

prior to the time the particles contact the surface mixing the bentonite-air stream with a separately originating spray of binder material comprising a water based emulsion of asphalt which demulsifies upon contact with bentonite particles and forms a layer of asphalt solids interspersed with bentonite particles.

18. The process of claim 17 including the steps of passing the bentonite-air suspension through a first conduit, positioning a liquid spray nozzle adjacent the outlet of said first conduit, so the direction axis of spray is at an angle to the direction of movement of the bentoniteair suspension thereby passing a substantial portion of the liquid binder from said spray nozzle in direction to intermix with said bentonite-air suspension prior to the time the bentonite-air suspension contacts the surface.

19. The process of claim 18 further characterized in that said spray nozzle for said liquid binder is positioned at an angle with respect to the axis of movement of said bentonite-air suspension when said bentonite exits said first conduit, said spray nozzle being positioned to have a portion of the spray from said nozzle outside of the bentonite-air suspension, and including the step of moving said conduit so that as the surface is coated, firs't the sprayed binder material only contacts the surface, and subsequently the mixture of binder material and bentonite contacts the surface.

20. The process of claim 19 wherein the surface is on an exposed subterranean wall and including the steps of spraying the binder material and bentonite-air suspension on the wall to form a binder lattice work throughout the bentonite layer on the wall, backfilling the wall and per- 14 mitting the binder material to disintegrate to form lines throughout the layer of bentonite,

21. The process for spraying dry particulate bentonite onto a surface to form a waterproofing layer comprising the steps of passing dry particulate bentonite in gaseous fluid suspension thifough a conduit, discharging the dry particulate bentonite and air suspension from the conduit in a stream at position spaced from and directed toward said surface; spraying a liquid binder material into the bentonite-air suspension stream after the bentonite has been discharged from the conduit and before the bentonite contacts the surface.

22. The process {of claim 21 further characterized in that the liquid binder material is also sprayed onto the bentonite and wall as the bentonite contacts the wall.

23. The process of claim 21 further characterized in that the liquid binder material is a sprayed emulsion having a water base and carrying solid materials and in which the solid material demulsifies as the material contacts the bentonite.

24. A process for applying sodium montmorillonite bentonite particles to a surface to be waterproofed comprising suspending dry bentonite particles in an air stream and directing the air. stream-bentonite suspension onto the surface to be waterproofed, intermixing said bentonite in the air stream suspension with a binder material comprising pliable solid material in a water based emulsion in a critical state wherein the solids demulsify upon contact with the sodium montmorillonite, the binder material being applied in a sufficient ratio to the bentonite to cause the bentonite to adhere in a layer on the surface to be Waterproofed, said intermixing of the bentonite and air suspension with said binder material being performed at least partially as the bentonite in the air stream suspension is moved toward the surface.

25. The process of claim 24 further characterized in that the solid materials are held in suspension with an anionic emulsifying agent.

26. The process of claim 24 further characterized in that the solid material is asphalt.

27. The process for spraying bentonite particles onto a surface to form a waterproofing layer on the surface comprising the steps of passing bentonite particles in a gaseous fluid suspension through a conduit, discharging the bentonite and air suspension from the conduit in a stream at position spaced from and directed toward said surface; spraying a'. liquid binder material comprising a slow setting asphaltic emulsion into the bentonite-air suspension stream after the bentonite has been discharged from the conduit and a substantial part of binder being mixed with the bentonite prior to the time the bentonite and binder contact, the surface, said asphaltic emulsion ranging in solid asphalt content up to 68 percent and being applied at a rate wherein the weight of the liquid binder material equals 10 to 30 percent of the weight of the bentonite.

28. The process of claim, 27 further characterized in that the solid asphalt content ranges from 55% to 65%, and the emulsifying agent is vinsol resin, and further wherein the emulsion includes from .5% to 4% by weight of anionic latex.

References Cited UNITED STATES PATENTS 3,336,146 8/19457 Henschel 106-287 E X 2,458,220 11/1949 Striegel et al 239--415 2,662,064 12/1953 Mead 52 -515 X 2,326,045 8/1943 McConnaughay 9423 EDWARD G. WHITBY, Primary Examiner US. Cl. X.R.

s2 s15, 741; 1 06170, 193 I, 208, 209, 277, 283; 117-10 4 A, 104 B, 123 c, 123 E, 161 A, 161 c, 163, 165, 168, Dig. 9; 260-47 R, 28.5 As