Water barrier

A waterproofing sheet used to waterproof structures above and below grade has a single layer of non-degradable, water impermeable polymeric membrane that has layers of particles of non-hydrated sodium montmorillonite (sodium bentonite) adhering to the membrane in a uniform layered thickness. The layers of particles of sodium montmorillonite spaced from the membrane adhere to each other, with a coating material (adhesive) that is designed to provide the necessary performance for waterproofing under a high water head (hydrostatic pressure). The material is in sectioned sheet or roll form and can be easily applied on the job.

BACKGROUND OF THE INVENTION 
1. Field of the Invention. 
The present invention relates to waterproofing processes and materials, and 
in particular a sheet laminated with non-hydrated granular bentonite for 
applications for waterproofing. 
2. Description of the Prior Art. 
Various bentonite type waterproofing panels have been advanced in the past. 
In particular, American Colloid Company, of Skokie, Ill. has obtained 
numerous patents on various water barrier panels, but they all have 
limitations in use. Generally speaking, these panels are easily damaged, 
and lose their ability to function if not handled carefully. A typical 
water barrier panel is shown in U.S. Pat. No. 4,048,373 which comprises 
two opposing spaced sheets using a sealing composition between the sheets 
that has bentonite in it, with a water soluble dispersing agent. This type 
of a panel is used against a foundation to act as a water barrier 
shielding the foundation, and is essentially a corrugated paper board 
carrier filled with finely granulated bentonite. This patent does describe 
the well-known waterproofing characteristics of bentonite, but the 
structure disclosed fails to provide the durability and adaptability of 
the present device. 
U.S. Pat. No. 4,048,373 is a continuation in part of U.S. Pat. No. 
3,949,560 which includes substantially the same disclosure, and a 
divisional patent U.S. Pat. No. 4,103,499 also shows the same type of a 
water barrier panel. Related U.S. patents, from the same family of 
applications, include U.S. Pat. Nos. 4,021,402 and 4,139,588. 
American Colloid Company also has two additional related U.S. Pat. Nos. 
4,126,543 and 4,194,970 which show a method of screening bentonite 
material for use in obtaining correct size bentonite particles. These 
patents do not show waterproofing panels as such. 
U.S. Pat. No. 3,186,896 shows a facing sheet quite similar to that 
described in the prior patents, comprising a barrier panel made of 
corrugated paper board that is filled with bentonite. 
U.S. Pat. No. 4,084,382 relates to a method for containing water having a 
high concentration of water soluble industrial wastes to reduce the 
likelihood of the wastes destroying the bentonite used. The bentonite is 
mixed with a water soluble dispersing agent and a water soluble polymer in 
a particular ratio to form a sealing compound. 
U.S. Pat. No. 3,466,827 shows a roof panel that is formed to provide 
impervious construction, and is a self-sealing panel using a finely 
divided soluble bentonite clay in a layer. 
U.S. Pat. No. 4,070,839 shows a moisture impervious panel that has a pair 
of spacing sheets interconnected by a central rigid support sheet, such as 
corrugated fiberglass. The corrugated sheet forms long pockets filled with 
a composition of bentonite and a compressed filler such as vermiculite. 
This construction forms a very rigid panel that is not usable in any form 
other than smaller sheets, and does not have sufficient flexibility to 
accomodate any substantial shifting of the surfaces that the panels are 
covering. 
U.S. Pat. No. 4,467,015 shows another type of structure that has two 
layers, and which can be formed into a roll. Each layer includes a sheet 
of water permeable material and a coating of dry particles of bentonite on 
one surface of the sheet. An adhesive is used for applying the particles 
of bentonite to the water permeable material, and the bentonite particles 
are placed so that they face the surface of the structure that is to be 
waterproofed. The sheet shown in U.S. Pat. No. 4,467,015 has inherent 
problems with the cardboard or water permeable sheet, namely migration of 
water and leaking at the joints until the material attempts to self-seal. 
The material also is susceptible to rain damage and it needs protection 
against the weather when installed, until it is covered by backfilling or 
the like. 
U.S. Pat. No. 3,676,198 shows apparatus for entraining bentonite particles 
in an air stream, and intermixing the particles with a coating material to 
cause the mixture to adhere in a layer onto a wall surface 11, and provide 
for a waterproofing layer in that manner. The patent requires special on 
site installation equipment. 
U.S. Pat. No. 4,534,926 shows an uninhibited bentonite composition which 
comprises an intimate mixture of bentonite clay with polypropene, 
polybutene or mixtures thereof. The material is capable of being extruded 
through an extrusion dye and further a sheet like material can be put 
between two release papers, but still has to be formed through an 
extrusion dye that has a wide opening to form a type of sheet. 
Thus, while the prior art shows various attempts at forming panels that use 
bentonite for waterproofing, and even though the desirable properties of 
bentonite for waterproofing have been known, the problems remain in 
obtaining a waterproofing sheet that is easily used; that withstands 
weathering; that seals leaks and seals well at joints and will continue to 
provide waterproofing over a span of time. 
SUMMARY OF THE INVENTION 
The present invention relates to a waterproofing sheet and method of using 
the same wherein the sheet is made of an impervious flexible material or 
membrane (impervious to water), and has a layer of granular bentonite 
adhering to one surface thereof. The bentonite particles also adhere to 
each other to form the layer that has structural integrity sufficient to 
permit the sheets to be rolled or handled as large sheets. 
In one form shown, the two intersecting margins (one side and one end) of a 
sheet are made so that there are no particles for a short distance along 
the edges of the polymeric sheet, to provide for a sealing overlap of one 
edge of the membranes onto the edge of a second sheet of the membrane. 
This provides seal lines that can be caulked, welded or adhesively sealed, 
to create a tight cover of panels over the structure. The water impervious 
membrane provides a primary line of waterproofing, and if, for example, 
the membrane gets pierced, the water penetrates into the bentonite layer 
and the bentonite will expand into the ruptured membrane opening to form a 
seal. Water soluble dyes can be added to or incorporated into the 
bentonite to assist in the identification of the area of a leak because as 
water enters the bentonite, the dye will dissolve and the leaking water 
will then stain the leak area to make it visible, even after the problem 
areas have been back filled or covered. Repairs to the membrane rips or 
tears can then be made. 
Many polymeric materials which are currently not in use as above grade 
roofing or below grade waterproofing products because of the great 
difficulty in causing them to adhere to the building wall or substrate can 
now be used because the bentonite layer when wet holds the membrane in 
place as well as providing additional waterproofing characteristics. 
Polymers such as high density polyethylene and polypropylene can be used 
for the membranes in the present device. Further, chlorinated 
polyethylene, polyvinylchloride, neoprene and butyl sheets can also be 
used and by adding the layer of bentonite the sheet composite becomes 
self-sealing, anti-water migration roofing material without the expensive 
necessity of fully gluing the membranes in place on the building surface. 
The present invention utilizes a layer of water impermeable polymer, and is 
usually installed polymer side out. The bentonite is protected from rain 
damage by the polymer when it is put into place. If a tough polymer is 
used, such as high density polyethylene, a product that is not susceptible 
to damage is achieved. 
The bentonite layer eliminates the need for tightly adhering a membrane to 
the wall or roof structure to stop water migration, because if water tends 
to get under the membrane and contact the bentonite, the bentonite is 
self-sealing and swells to stop any migration immediately. Water migration 
between membranes and a substrate has been a cause of great unsatisfaction 
of users of buildings, and has been the cause of innumerable lawsuits. 
Again, the present invention permits identifying the source of damage to 
the membrane, and the bentonite layer provides for self-sealing 
immediately. 
As disclosed herein, an apparatus for manufacturing the waterproofing sheet 
composites is disclosed which provides for individually adhering a single 
particle thick layers onto the membrane, with a layer of adhesive, and 
then subsequently adding additional single particle thick layers until the 
desired depth of the particles is achieved. The backing membrane, as 
disclosed high density polyethylene, is carried on a conveyor up an 
incline, and a spray bar is positioned to apply a thin layer of adhesive 
directly to the polyethylene membrane. The adhesive is selected to be one 
that adheres to the membrane, and a wide range of adhesives will work. 
Then, as the membrane moves along with the conveyor, a single particle 
thick layer of bentonite particles is deposited on the adhesive above a 
conveyor-membrane agitator that provides a frequency of vibration to the 
conveyor in a direction perpendicular to the conveyor belt so that the 
particles tend to dance upwardly and form a standing wave of particles 
that lift from the belt and tend to fall downwardly under gravity. The 
conveyor belt is inclined upwardly in its path of travel, and the 
particles tending to move downwardly will fall into place on the adhesive 
layer and will be held in place in a single thickness of particles. The 
rate of feed of the bentonite particles can be controlled in a 
conventional manner so that excessive particles are not provided. A 
uniform single particle thick layer is thus provided on the membrane. 
The conveyor moves the membrane to a second station where an additional 
thin layer of adhesive is sprayed onto the previously deposited layer of 
particles, and then another layer of particles is deposited on the second 
layer of adhesive, in the same manner as described. The second layer of 
particles increases or doubles the thickness of the particles on the 
membrane, and this process is repeated in sequence until a desired depth 
has been deposited on the membrane. 
The membrane formed into the composite waterproofing sheet is carried on 
the conveyor belt downwardly, and can be passed through sizing rollers 
that will compress the layers of particles into the adhesive to insure 
good adherence as well as a uniform thickness of the finished product. 
The finished composite waterproofing sheet product is then placed into 
rolls for storage and shipment to the job site, where it is installed as 
described above or is cut into individual panels of desired size. The 
method of manufacture makes it possible to provide rapid and accurate 
formation of the bentonite layers, thereby increasing efficiency.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 illustrates a finished composite waterproofing sheet product 12, 
made according to the present invention and comprises, preferably a 
membrane 10 of material that is impervious to water, such as high density 
polyethylene, and a thickness or waterproofing layer of bentonite or 
sodium montmorillonite indicated at 11. 
It is to be understood that the layer 11 is meant to indicate a finished 
thickness of bentonite made up of a number of layers, each having a 
thickness of an individual bentonite particle with interspersed adhesive 
layers, made into a sandwich type composite waterproofing sheet 10. 
In manufacture, an edge portion 13 of the membrane or sheet 10 may be left 
without the layer 11 of particles, as shown in FIG. 2, so that the sheets 
or panels can be lapped. The lapping edge portion 13 in FIG. 2 along a 
longitudinal edge, and if smaller panels such as four foot by four foot 
panels are used, an edge portion 14 of the membrane will be left uncoated 
along one end of the panel as well. In this way the panels (or long strips 
or sheets) can be lapped where they meet, for holding them together when 
initially installing them, and also to permit the seams to have a 
continuous impervious membrane layer facing out from the surface. It 
should be noted that the composite waterproofing sheets are installed with 
the water impervious membrane facing outwardly to the elements. 
Thus the composite structure comprises a flexible water impervious membrane 
in sheet form having a layer of particles, for waterproofing, preferrably 
bentonite particles, on the surface at a desired depth. 
Adhesives that provide proper holding action are also important. While the 
prior art shows various adhesives that will work with bentonite, bentonite 
is highly reactive to many monovalant, divalant and trivalant materials. 
Bentonite also may form a permanent association with numerous other 
elements and compounds, and such products should be avoided in making the 
composite waterproofing sheets so that the bentonite particles do not 
react and lose their desirable property of swelling when contacted by 
water. When reactions do occur, or association of the bentonite particles 
with other elements occur, the waterproofing capabilities are degraded, 
because the bentonite material does not have the ability to swell and 
waterproof. The choice of adhesive is carefully made for making the 
composite waterproofing sheet 10, the adhesive has to have the ability to 
adhere the bentonite particles to a polyethylene or other water impervious 
membrane, and minimize the degradation of the waterproofing capabilities 
of the bentonite. Adhesive materials are available as emulsions with 
water, solutes, concentrates, hot melts and often in homo or copolymer 
status. Almost any adhesive originating from a solvent, emulsion with 
water, hot melt or water emulsified solid may be used, and the choice is 
determined by the ability to wet, its stickiness, the polar activity and 
the final adhesion performance. The choice is influenced by price, 
toxicity, availability, or environmental considerations as well. The 
addition of wetting agents, emulsifiers, dispersants and preservatives for 
latexes can cause deterioration of the bentonite' s ability to waterproof 
or reseal, so use of those products may be minimized. 
Adhesion to high density polyethylene has been difficult, and a common 
procedure to enhance adhesion is to chemically disturb the surface of the 
polyethylene or polymer membrane just prior to the application of the 
adhesive, for example by treating it with ozone. This brings in time 
limitations which means that the membrane has to be coated quite quickly 
because the molecules that are affected by the treatment migrate back to 
their original smooth alignment relatively fast. 
The total thickness of the layers of bentonite particles is built up to in 
the range of 1/8 inch to 1/4 inch thick, and thus a method of continuously 
achieving a permanent adhesion to the polyethylene membrane is required. 
The surface of the polyethylene preferrably is roughened, and as shown 
herein, it can be done by stretching the polyethylene to microscopically 
"craze" the surface of the polyethylene. The amount and the direction of 
the tension applied to the membrane is determined by the thickness of the 
membrane. Generally, tensioning the membrane to about 30 lbs per square 
inch is acceptable for thicknesses of 2 to 20 mils. The membrane used 
herein is most preferably in the range of 20 mils, but the preferred range 
is 15 to 100 mils in thickness. As will be explained, tensioning can be 
done by passing the polyethylene membrane over rollers which apply a 
stretch between pinch drive rollers. 
The adhesive used must wet the polyethylene surface for good adhesion, and 
low surface tension solvent systems provide a suitable vehicle to carry 
the adhesive. 
Alaphatics, aldehydes, ketones, carbon/halide and ring compounds all have 
utilization. Common carriers/solvents include toluene, lower molecular 
weight alcohols, methyl ketone, and water. For example, the following 
products act as suitable adhesives. 
Asphalts (with or without fillers and elastomers) 
Butylenes 
Butyl Rubber 
Acrylics 
Propenes 
Styrene/butadiene 
Nitriles 
Vinyls 
Water Soluble: 
Cellulosics 
Saccharides 
Gums 
Proteins. 
In general, the adhesive solids should be present in concentrations from 
about 5 to 100% by weight, and are mixed with bentonite in ratios of 
between 3 and 50% by weight of the adhesive relative to the particles 
(bentonite). 
Referring specifically to FIG. 6, the method of prestretching the 
polyethylene for applying the adhesive is illustrated schematically, and 
is a conventional method for stretching sheets of materials. The structure 
shown therein can constitute the polyethylene supply for the main machine 
which will be discussed. A roll of polyethylene membrane material or other 
suitable sheet material is indicated at 20, and the membrane is passed 
through a pair of pinch rollers 21, which are driven from a motor 21A at a 
first speed and clamp the polyethylene membrane so it is driven at this 
set rate. The polyethylene is then run over suitable tensioning rollers 
indicated generally at 22 and 23 (more tensioning rollers may be used), 
and then the membrane is passed through a pair of pinch drive rollers 26. 
The drive rollers 26 are also driven by a suitable motor 26A, and tension 
can be applied to the membrane by driving the rollers 26 at a different 
(faster) lineal speed than the rollers 21. The membrane will be tensioned 
because of the differential in speed. 
Another way of stretching the membrane would be to run a section of sheet 
material between the first and second sets of pinch rollers, and then move 
the rollers, or guide rollers 22 and 23, in opposite directions (indicated 
by arrows) to stretch the membrane 10 a desired amount, and then 
subsequently run an additional length of material onto the stretching 
idler rollers. However, in a continuous process, the method of tensioning 
or stretching the polyethylene membrane (or other membrane) can be used 
applying known principles, and thus the showing is done only schematically 
herein. Additionally, treated polyethylene can be obtained that has the 
ozone treatment previously mentioned. 
FIG. 3 illustrates schematically the method of applying adhesive and 
particles to the water impervious membrane. The material supply indicated 
generally at 30, which can comprise a roll, if the membrane is treated, or 
the stretching rollers and drive shown in FIG. 6, provides a continuous 
sheet of the membrane 10 that passes over a guide roller 31, and then is 
fed onto the top of a conveyor belt assembly indicated generally at 32 
having an endless belt 32A. As shown, the conveyor belt assembly is 
schematically represented as having a drive roller 33 at its upper end, 
and an idler roller 34 at its lower end over which the belt 32A is 
mounted. The conveyor belt 32A and thus the membrane sheet 10 are inclined 
in the range of 20.degree. to 50.degree. with respect to a horizontal 
plane. The conveyor belt incline is matched with a downwardly extending 
conveyor section 38 that may be rollers or a conveyor belt and which is 
shown only partially, on which the membrane sheet 10 will run after the 
particles have been applied to form the composite waterproofing sheet 12. 
The downward incline is to insure that the membrane 10 will be carried 
upwardly by the conveyor belt 32A because there will be a downward 
component of loading tending to keep the membrane 10 moving upwardly on 
the incline. There will be some friction between the conveyor and the 
undersurface of the membrane as well. If needed, drive rollers can be 
utilized. The conveyor belt can be open mesh, a rubber coated belt or any 
desired construction. 
The membrane sheet 10 has a surface that faces upwardly and as it is 
carried up the incline, the membrane 10 passes through a first particle 
application station indicated generally at 35, a second station indicated 
generally at 36, and a third station indicated generally at 37. More 
application stations are generally used, but the stations illustrated show 
the method. Each station 35, 36 and 37 includes an adhesive supply 40 
feeding an adhesive through a feed control 40A to a spray bar 41 that 
extends transversely across the width of the membrane sheet 10. If the 
membrane is in the range of 4 feet wide, the adhesive bar would be that 
long. Known adhesive spray bars can be utilized. The adhesive used can be 
selected from the group previously listed, and as shown by the dotted line 
representations at 42, the adhesive is sprayed in a thin layer onto the 
moving membrane in a first processing region indicated generally at 43. 
The coated membrane 10 moves upwardly a distance on the inclined conveyor, 
and a second portion of the station 35, comprising a bentonite hopper 46 
having a transversely extending feed section 47 of conventional design 
also controlled as to rate of feed with a conventional rate of feed 
control 49 applies a uniform, relatively thin line of bentonite particles 
indicated at 48 across the membrane. The bentonite particles drop onto the 
conveyor, immediately above or in the vicinity of a rotating beater bar 52 
that is mounted in a suitable manner on bearings at opposite ends and is 
driven from a motor 53 to rotate at a desired speed. The beater bars 52 
has two radial longitudinal extending lugs 54 on opposite sides thereof 
(diametrically opposed). Two positions of the lugs are shown in FIGS. 4 
and 5, one in dotted lines. The lugs 54 strike the conveyor belt on its 
undersurface and vibrate it upwardly to bounce the bentonite particles 
upwardly from the belt and the membranes (at least particles that have not 
initially adhered to the layer of adhesive) and the loose particles then 
will tend to fall back into the region shown at 55 in FIG. 3. A type of 
"standing wave" of individual particles is created because they will tend 
to fall back onto the membrane and be replaced by new particles bounced in 
the air by the beater bar. The particles which have touched the adhesive 
move upwardly with the membrane, but are locked in place. 
This low frequency, vertical vibrating action dislodges nonadhered 
bentonite particles, and insures that a totally adhered, uniform single 
particle thick layer is applied to the first adhesive layer in station 35. 
As the conveyor belt 32A and membrane sheet 10 move through the second 
station 36, the layering action is repeated. The second sprayer bar 41 
applys a thin layer of adhesive in a region shown at 57, which would be 
applied on the upper surface of the first layer of bentonite particles, as 
well as flowing slightly in between any spaces in the bentonite particles 
forming the first layer. The rate of feed of adhesive can be controlled 
with feed control 40A. A second bentonite hopper 46 with a feed assembly 
47 and rate of feed control 49 will apply another individual particle 
layer onto the first layer of particles and the second layer of adhesive 
applied in the region 57. The hopper 46 at the second station 36 is also 
immediately above a beater bar 52 that is driven from a motor 53 as well. 
This beater bar acts as before and forms a second standing wave or 
particles to cause a second, single particle thick layer of particles to 
form on top of the first layer of particles, so that now there are two 
layers of particles adhered to the upper surface of the membrane 10. 
In the third station 37, the same action occurs, and here the adhesive is 
applied in a section 60 of the membrane. A third layer of adhesive is 
applied in section 60 with a third spray bar 41, and when the applied thin 
layer of adhesive is moved up under the third station bentonite hopper 46, 
the feed of particles from the feed section 47 of the third station 37 
falls down onto the new or fresh adhesive layer to form a third layer of 
particles on the membrane. The particles are deposited above a third 
beater bar 52 driven from a motor 53 to form a standing wave 55 at station 
37, forming the uniform, single particle depth third layer of material. 
The number of layers of particle material desired, to achieve the desired 
thickness determines the number of individual stations that are utilized. 
This process may be used for forming adhering layers of particles to 
membranes or sheets for various uses, such as single layer sandpaper or 
nonslip pads, as well as for waterproofing sheets. 
FIG. 4 illustrates in greater detail the individual layers of particles 
indicated at 61, 62 and 63, which would be applied after the adhesive 
station in the region 60 of the membrane. The conveyor belt movement 
direction is indicated by the arrow 65, and it can be seen that the beater 
bar forms a standing wave section shown at 66 where the particles tend to 
make a loop, and the particles that are falling rearwardly will fall down 
onto the adhesive from the spray bar that applies the adhesive in the area 
60 and to retain a single particle thick layer. The adhesive layer is 
controlled in thickness to accomplish this purpose. 
FIG. 5 illustrates the forces and the amplitude of movement caused by the 
beater 54. The conveyor belt and membrane deflect upwardly as shown in 
dotted lines at 70, tending to throw or project the particles upwardly 
from the belt as shown by the arrow 71. The particles then fall under 
gravity generally downwardly, at the same time the conveyor belt and 
membrane are moving upwardly in the direction as indicated by the arrow 
65, so that the adhesive coated particles indicated generally at 72, with 
the fresh layer of adhesive on top will collect the next layer of 
particles to form the uniform depth layers. 
The upward force vector is shown by the vertical arrow 71, gravity is shown 
by the arrow 75, and the individual particle indicated at 76 is falling in 
direction along the arrow 75 as a direction of return. A standing wave 
again is shown generally at 66 where the particles tend to loop over and 
adhere to the adhesive. 
The sequence is applying adhesive, and a uniform single particle thick 
layer across the surface of the membrane sheet of material (leaving an 
edge portion for the lap seam shown in FIG. 2) and then applying a uniform 
layer of particles above a vibrator or beater, so that the particles 
adhere as the material is moved in an upwardly inclined plane. Additional 
layers are added at additional, individual stations positioned in sequence 
along the inclined membrane. 
Nonadhering particles are problems in an adhesive layer, and in the present 
device, non-adhering particles would act as a bond breaker, or separation 
with subsequent layers. Such condition (non-adhering particles) causes 
delamination and separation which leaves the waterproofing sheet 
unsuitable for use. It could not be transported, handled for installation, 
nor provide proper waterproofing qualities. The method described, using 
the beaters, insures that every particle is tested to insure it is fully 
adhered to the adhesive before a new layer is added. the apparatus 
performs in situ testing of the particle bonds. 
Large particles applied in a single layer and premixing the adhesive with 
the particles does not form a uniform thickness, leaves voids and spaces, 
and separates when folded around outside corners of a structure. Another 
way of attempting to add particles to a membrane has been to wet the 
membrane with adhesive and then pull it through a supply of particles. 
This wipes off adhesive and generally is unsatisfactory. 
The present process shown utilizes a minimum amount of adhesive, with a 
controlled ratio of adhesive to particles. Because a fresh layer of 
adhesive is applied at each station, dry areas are prevented and a uniform 
thickness is achieved. Particle size of bentonite can range up to 150 
mesh, using standard mesh sizes for bentonite. The beater tends to cause 
the unattached particles to become airborne, and the loose particles will 
continue to be forced back into the adhesive to form the standing wave 
explained. 
The ratio of adhesive to particles is easily controlled by the size of the 
nozzles, pressure and the spray bar, as well as the rate of feed of the 
particles. Two to 12 pounds of adhesive to 40 pounds of particles is a 
range that is generally satisfactory, and it should be pointed out that if 
too much adhesive is used, it will tend to flow downwardly and not be 
carried up the incline. The dry particles are kept airborne by the 
beaters, so that they will not pass through the station until they have 
lodged in adhesive and adhere in a desired layer. 
The particle size can be between 5 and 150 mesh using standard U.S. 
standard mesh sizes. If desired air entraining of particles (fluidizing) 
can be used for feeding the particles. Lowering the amplitude and 
frequency of the beater bar at the final station will cause the production 
of a dry particle coating over the entire layer, which would tend to have 
a little less adherence, but it would be an immediate physical state for 
packaging. The beater bars generally in the final station would have an 
amplitude of about 1/8 of an inch with a frequency of about 100 rpm (200 
beats per minute). The amplitude of the "beat" is limited by the force of 
gravity, i.e. how fast does the conveyor belt resume its original position 
before being "hit" again by the rotating beater. 
In the other stations, the amplitude of the beater bar and the rotational 
velocity of the beater in relation to linear velocity of the conveyor belt 
is selected to be proper for the angle of inclination of the conveyor 
belt. For example, an amplitude of the beater of a 1/8 inch rotating at 
180 rpm, when the velocity of the conveyor belt is approximately 25 feet 
per minute with an angle of incline of 30.degree. results in the bentonite 
particles being knocked back about two inches so that the standing wave 
develops in an area of the membrane about two inches behind the beater 
bar. The particles returning from the area of beating, plus the newly 
supplied particles provide the uniform coating that sticks to the 
adhesive. The coating or composite layer of bentonite preferably ranges 
between 0.75 pound and one pound per square foot for adequate 
waterproofing capabilities. 
The coating or composite layer of bentonite is built up to a weight of 
about one pound per square foot for adequate waterproofing characteristics 
for the composite waterproofing sheet 12. 
A part of final sizing, compression rollers 80,80 are shown. These rollers 
are mounted on a frame 81 and driven with a motor 82 at a desired speed, 
syncronized with the membrane speed of movement. The rollers 80 extend 
across the composite sheet and compress the membrane layers of bentonite 
particles together to provide a uniform depth layer and to force the 
particles to be sealed in adhesive. 
Water soluble (misable) colorants may be added to the bentonite layer. When 
present, these colorants dissolve in the water and make a stain when water 
leaks through any damage such as a rip or tear in the non-permeable 
membrane 10, thus clearly marking the size, location and origin of the 
leaking water. 
This capacity is especially valuable on horizontal surfaces such as roofs, 
decks, plazas, etc. This feature could not be used if the membrane were 
not impermeable to the passage of water. 
Common water misable or soluble dyes such as used in easter eggs 
(non-staining) or tracing dyes which are used in extremely small 
quantities such as the ultraviolet flourescent family, i.e. the material 
sold by E. I. Dupont Denemours Company under the mark "Flouresene", would 
also be suitable. 
The mechanical components and conveyors may be suitable, commercially 
available components and thus the spray bars, hoppers and rollers are 
shown only schematically. 
This invention makes possible a waterproofing installation to the substrate 
under a floor prior to the concrete pour. It would be installed bentonite 
side facing the earth with each sheet overlapped along its edges as 
explained. 
Although the present invention has been described with reference to 
preferred embodiments, workers skilled in the art will recognize that 
changes may be made in form and detail without departing from the spirit 
and scope of the invention.