US2277286A - Method and means for impeding the seepage or flow of water - Google Patents

Description

P. BECHTNER 2,277, 8 METHOD AND MEANS FOR IMPEDING THE S'EPAGE OR FLOW OF WATER March 24, 1942.

Filed Nov 19 56 INVENTOR IDAUL BECHTNER BYg ATTORNEYS I MJ J description.

Patented Mar. 24, 1942 UNITED STATES [PATENT OFFICE METHOD MEANS FOR IIVIPEDING THE SEEPAGE OR FLOW OF WATER- Paul-Bechtner, Chicago, Ill. assignor to American Colloid 00., Chicago, 111., a corporation of South Dakota Application November 5, 1936, Serial No. 109,245

13 Claims.

This invention relates to improved methods and means for impeding the flow of water and for reinforcing structures to prevent the seepage of water therethrough. The seepage and flow of water through earthworks, dams, ma-

sonry constructions, water barriers and the like causes untold economical loss, much of which can be prevented by the. invention herein described.

Seepage through water barriers, such as dams,

cofierdams, and water-retaining walls may be caused by any of several conditions. The bedrock may not be impervious to flow. The circumstances may require that the barrier be placed on porous bodies of materials such as sand shrinkage of the setting concrete away from the,

walls against which it is cast. Such leakage, once started, sometimes results in destruction of the wall and complete release of the backed-up water.

Similar problems are encountered in efforts to exclude water from core trenches, excavations and "foundation walls of buildings and to confine water to prescribed ditches or channels, In fact, these are but a few of the many circumstances under which it is highly desirable yet diflicult effectively to prevent the flow or seepage of water. I

An object of my invention is to Provide improved methods and means for inhibiting the seepage of water through pervious structures and for safeguarding against seepage or flow through structures that are normally impervious but ,capable of developing leaks.

Another object is to provide improved barriers which are constructed better to insure against water seepage or flow.

Another object of my invention is to provide such methods and means which are-permanently effective regardless of shrinkage, cracks, or

shocks and distortions caused by subsidence,

earth movements and the like.

Another'object is to provide special methods and means by which it is possible to correct existing conditions of seepage or flow without requiring freedom from contact with the water.

Stillcfurther objects and advantages of the invention will be apparent from the following I have discovered that water seepage may be prevented and that structures of various types may be safeguarded against-leakage by blocking the path of. flow of .the water with bentonitic or highly colloidal clay which possesses the capacity to swell and gelatinize upon contact with water. The type of clay best suited for the present' purposes is the true bentonite obtained in regions of Wyoming and South Dakota, although other highly colloidal, or bentonitic clays which possess the property of swelling and gelatinizing in water to a substantial degree are also useful. The degree of their efiectlVeness depends upon the closeness with which this swelling prop-- 15. erty corresponds to that of true bentonite.

True bentonite is a material consisting principally of the mineral Montmorillonite and occurring naturally in combination with about to 45% water. For commercial use this mate- 20 rial is dug, dried to contain about 9% moisture,

and then granulated or powdered. Some physical characteristics which distinguish bentonite from other clays are its permeable texture and its extremely small grain size. From 65 to 70% of the grains of a Wyoming bentonite are finer than .2 micron; over 85% are finer than 2 microns. -These grains or particles, when wetted, adsorb films of water that are thicker than the films which form on other clay-like materials,

and after 'the bentonite has been wetted the water cannot be expelled, even at high pressures.

The strong adsorptive power of commercial bentonite, which will adsorb almost five times its weight of water, is therefore partially attributable to the preponderance of extremely small grains or particles, providing tremendous surface area for the exertion of adsorptive powers, and the film retaining capacity of these particles.

w Commercial bentonite swells, when contacted with water, as much as 10 to 20 times its dry volume. One factor which causes this swelling is the separation of the small particles by the water films adsorbed thereon. Another is the distinctive nature of the particles themselves,

which are composed of minute plate-like struc tures that possess the peculiar property of allowing water molecules to penetrate their crystal lattice. The crystal structure itself is thus expanded. A third factor is the mutual repulsion of the particles, due to like negative polarity. 3

In its swollen condition bentonite has several advantageous properties; it will carry materials in suspension; it exerts a cohesive effect; when left quiescent it forms a permanent gel the viscosity of which increases upon aging. An important aspect of the swelling of bentonite which I have discovered is that it will swellv only to the extent necessary to flll available space, without exerting substantial pressure when confined against further swelling. Another important quality is that repeated drying and contraction of swollen bentonite in no way impairs its capacity to swell again upon renewed contact with water. These properties make it an ideal material for incorporation in a dry or slightly moist state into dams and other water barriers, at points where leakage possibilities occur, so that in case cracks or other leakage develop the bentonite will come into contact with the leaking water and swell to stop the leak but will not create pressure which might cause further breaks.

I have discovered that a blanket or wall of bentonite which possesses the capacity to swell upon contact with water will permanently resist seepage or flow of water therethrough. When the bentonite is contacted with water it swells to fill available voids or spaces. Thereafter it is impervious, and it remains impervious to water as long as water is present. If water is not con-' tinuously present the bentonite may contract as it dries, but its resistance to seepage is immediately restored upon renewed contact with water.

I have found also that bentonite confined within masonry structures or the like, when wet,

does not exert swelling pressures suflicient to harm the structures in any way, yet it forms an impervious seal with the confining surfaces. Furthermore, the bentonite, either in dry or wet swollen condition, may be subjected to shocks, earth movements or subsidence without destroying its sealing power. The swelling capacity of the material is completely exhausted only when it is suspended freely in many times its volume of water. Accordingly, by utilizing a blanket or wall of bentonite to block the flow or seepage of water I am able to effect permanent impedence of such flow or seepage under many difficult conditions. Appropriate combinations pf bentonite and strength giving structure produce barriers that are resistant to water under great pressure.

Several preferred modes of practicing my invention are illustrated diagrammatically in the drawing, wherein Fig. 1 is a diagrammatical plan view of an embodiment of my invention in which inserts of bentonite are employed to reinforce a dam against water seepage.

Fig. 2 is a diagrammatical vertical section through a portion of a dam at a joint between the main wall of the dam and the-abutment.

Fig. 3 shows an application of my invention similar to Fig. 1 in which the bentonite is placed in wells adjacent the connection of the main portion of a dam with the wings thereof.

Fig. 4 represents a vertical cross section of another type of dam construction,.in which a blanket of bentonite is interposed between the bedrock and the bottom of the dam.

Fig. 5 illustrates the application of the invention to the closing of a mine or conduit against the flow of water therethrough.

Fig. 6 illustrates the use of a blanket of bentonite to protect the foundation wall of a building against water seepage.

Fig. '7 is a partial view, in vertical section, of a floor provided with an underlying layer of bentonite.

Fig. 8 represents, in cross section, a trench or ditch bordered by a blanket of bentonite in such manner as to prevent the seepage of water from Fig. 10 shows another embodiment of a structural unit.

In Figures 1 to 4, inclusive, I illustrate improved dam constructions utilizing the principles of my invention. Within the dam structure at points likely to be affected by seepage, cracks or the like, I provide inserts of bentonite so that water seeping through the structure will contact the bentonite.

For example, in the construction of Figure 1, the dam I0 faces against abutment walls I2 and I3, and at the meeting surfaces of these members wells l4 and I5, extending for the height of the dam into the concrete or other material of which the dam is formed, are provided. The wells are filled with a dry bentonitic clay having the capacity to swell and gelatinize upon contact with water. Figure 2 may be considered as a section taken vertically along the axis of the dam and through the well IS. The abutment I3 is illustrated as comprising a concrete portion positioned on rock at I8. Well I5 extends, for the height of the dam, across the joint I 6 between the main wall I 0 and the abutment, and it is filled with bentonite as indicated at ll.

Figure 3 represents an arch-like dam having a central wall 20, wings 2| and 22, and, at the joints between the wall 20 and the wings, wells which confine masses 23 and 24 of bentonitic clay. In Figure 4, a dam 25 positioned on bedrock 26 is provided with an insert of bentonitic clay at 21, bridging the seam between the dam and the rock.

Dams constructed with inserts of bentonite at points susceptible to leakage are surprisingly resistant to the passage of water. The shrinkage of setting concrete, earth movements, contraction and expansion due to changing temperatures, etc., are likely to result in water permeable seams and crevices. The presence of a mass of bentonite at such points, however, provides permanent protection against seepage. When the confined bentonite is contacted with water which has traversed the structure to the location of the bentonite it immediately adsorbs.

water, swells enormously, and forms a gelatinous mass which itself is impervious to water and provides an impervious seal with the confining walls of the structure.

Although the insert 21 of bentonite in Figure 4 is illustrated as surrounded by dam structure and bedrock, other arrangements may be followed without sacrificing results. Substantially dry bentonite is notable for its extreme density and compressive strength when packed into a compact mass. Wherever the bentonite is subject to flowing water currents which would carry away the gels as they formed this erosion may be prevented bymaintaining a layer of sand or other erosion resistant material between the bentonite and the flowing water. The bentonite then forms a tight-filter-cake on the surface of the sand.

Figure 5 is a diagrammatical showing of a construction which is effective to block the flow of water through mines, or water conduits in general. A pair of spaced forms or bulkheads 32 and 34 extends across a mine shaft 30, and a mass of bentonite or similar colloidal clay is located at 35 between these forms. The forms may be of wood, masonry or any other suitable material. 'The bentonite may be in finely digided form, or in the form of blocks or bricks, or it may be combined with other material, for example, sand or gravel.

In the use of this embodiment of the invention distinct advantages are obtained as compared with concrete walls and other types of barriers heretofore employed for the same purposes. The leakage permitted by the shrinkage of concrete walls away from the walls of a mine or conduit during the setting of the concrete is completely avoided. Whenever the form 32 allows backed-up water at 38 to contact the bentonite at 36, the bentonite first contacted adpermanently resistant to seepage. The same effeet is produced whether the water contacts the bentonite along the walls of the mine or conduit or remote from the walls.

A characteristic feature of this and the other embodiments of the invention is that the swelling sorbs water, swells and forms a gel which is penetration are obtained by the use of pure bentonite or pure bentonitic clay, I have discovered also that the resistance of the mass to high water pressures may be increased by employing mixtures of bentonite or bentonitic clay and other granular materials, for example, sand. For

. example, when a mixture of equal parts of benof only a small portion of the mass of bentonite,

the portion first contacted with water, is usually effective to block seepage through'to other portions of the mass. Thus these other portionsu'etain their full capacity to absorb and swell and block further flow or seepage in the event that the first gel formation should be disturbed.

Another important advantage .is that the ex"- pense and care incident to the. provision of barriers such as concrete walls are avoided. Theforms 32 and 34 need not be impervious to water; it is sufiicient that they give strength to the barrier and that form 34 include no openings permitting escape of the bentonite therethrough. The

be removed easily; whereas the destruction of a barrier composed of masonry is a difficult task.

My invention is also applicable to impede the blanket of bentonite is interposed as indicated at 44. As in the other embodiments described above, the bentonite swells when contacted with 5 water and forms an impervious barrier which prevents the water from seeping to and through or around the wall 40. An arrangement such as that shown in Fig. 7 is particularly suitable for the ground floors of buildings placed in low, damp ground. A blanket 41 of bentonite is placed on the base 46 for the fioor, and the fioor 48, which may be of concrete or any other suitablematerial, is applied over the bentonite.

Figure 8 illustrates a mode of applying the invention to the prevention of seepage from a ditch or the like formed in pervious soil. In the Between the foundation wall 40 of a construction of the ditch a blanket 52 of bentonite As the bentonite is contacted woth water it swells to form an impervious gelatinous barrier, one

tonite and beach sand is poured into a T-shaped section of 3 inch pipe to a height of 20 inches in the longer arm of the T and lightly tamped therein, the mass is not moved by continuing water pressures of 1000 lb. per square inch, and the water penetrates the mass a distance of only about 5 inches. W

An important advantage of the invention results from the variety of methods which may be employed to form the seepage-resistant mass of bentonite. In one embodiment ordinary commercial powdered or granulated bentonite may be used. Even when loosely put in place as by pouring, such finely-divided material provides a permanent barrier against seepage, since the swelling power of dry bentonite is so great that voids in the mass are blocked upon contact with water. The physical strength of such a mass may be increased by tamping or packing the bentonite in place.

Under som circumstances of use it is impractical to provide temporary or permanent supporting means for the bentonite before forming the mass; 1. e., the bentonite must be placed first. For example, in sealing a wall from the outside earth the most practicable procedure may be to form the mass of bentonite adjacent the wall and then fill in the earth. According to another embodiment of my invention this may be accomplished by incorporating the H bentonite with from one to one and a half times as much water to form a stiff putty-like mass which is sufiiciently cohesive to adhere to rough I ,where water is present by fashioning it roughly into bricks or blocks each having a quantity of dry finely-divided bentonite in its interior. Similar results may be obtained, as illustrated in Figure 9, by forminga bricklike body Ill of hentonite which has been moistened only sufficiently to produce slight coherence and then contacting the outsides of the body with water, as by dipping or spraying. The water does not,- penetrate far into the body but causes the bentonite at the surfaces thereof to swell and form a cohesive sheath or enclosure as indicated at '|2, which strengthens the unit so that it can be handled and placed in position. Another suitable proagainst leakage I cedure (see Figure is to use a fabric enclosure, for example, a paper cartridge as indicated at 80, filled with dry bentonite 82. Still another, which is useful under circumstances prohibiting the construction of a solid blanket of bentonite, as in the prevention of seepage through water covered porous rock or gravel structures, is to force a heavy pumpable suspension of bentonite into the structure and thus build up a blanket of bentonite in the path of seepage.

The' invention is not limited to the specific illustrative uses and methods of use described hereinabove, although these possess their own individual advantages. When dry or swellable bentonite is applied to expansion joints, shrinkage joints, or adjacent corners where cracks are likely to develop in concrete dams, or when used in any water barrier where, upon coming in contact with water, it will swell and stop the leakage, this is within the scope of my invention, and inasmuch as I have discovered that bentonite can be used in this manner without developing appreciable pressures on swelling, innumerable further uses for bentonite in sealing water barriers, based on the principles I have disclosed, will occur to those skilled in this art.

I claim:

l. A dam comprising a masonry wall positioned on a supporting bed and abutting against end abutments, said masonry having a compartment therein at a point susceptible to leakage, and a compact mass of swellable bentonite confined within said compartment.

2. A dam comprising a masonry wall positioned on a supporting bed and abutting against end abutments, a compartment extending along the joint between said wall and an abutment, and a compact mass of swellable bentonite filling said compartment.

3. A water dam comprising a concrete dam structure having pockets of swellable bentonite therein.

4. A self-sustaining structural unit for the for mation of barriers impervious to water comprising finely divided, slightly moist swellable bentonitic clay in the interior thereof and wet bentonitic clay constituting a cohesive enclosure therefor.

5. The method of making structures resistant to seepage or flow of water therethrough which comprises positioning a mass including swellable bentonite across the path of such seepage or flow and confining said mass between spaced rigid supporting structures, said mass being of sufficient thickness and bentonite concentration to swell and form adjacent the water face, when contacted by the water, a supported, water-impervious barrier of swollen gelatinous bentonite merging into swellable bentonite.

6. The method of preventing flow or seepage from bodies of water which comprises forming and supporting and confining across the water path a compact blanket of finely-divided, substantially dry swellable bentonite-of sufiicient thickness and bentonite concentration to swell adjacent its face upon contact by the water and form across said path a water-impervious barrier of swollen bentonite merging into a reserve mass of substantially unswollen bentonite.

7. The method of making structures such as dams, bulkheads, masonry walls and like water barriers impervious to seepage or flow therethrough from bodies of water, which comprises providing space in the structure across the path of such seepage or flow and filling into and confining within said space a mass of substantially dry, finely-divided swellable bentonite mixed with sand, said mass being of suflicient thickness and bentonite concentration to form across said path, upon contact by the water, a water-impervious barrier of swollen bentonite adjacent its face merging into substantially unswollen bentonite within the mass.

8. A water barrier comprising rigid supporting structures having space therein in the path of water seepage or flow and a compact mass of finely-divided swellable bentonite confined across said path in said space, said mass being of sufiicient thickness and bentonite concentration to swell at its face and form across said path, when contacted by water, a water-impervious barrier of swollen bentonite merging into substantially unswollen bentonite.

9. The method of blocking the flow of water under pressure through a determinate path which comprises restraining the water from a part of said path, forming across said path at said part a compact mass including substantially dry swellable bentonite of sumcient thickness and bentonite concentration to swell adjacent the water face and form across said path a waterflow from a body of water through a determinate V path comprising rigid supporting structure having space therein across the water path and a compact mixture of finely-divided swellable bentonite and granular material confined across said path in said space, said mixture being of sufficient thicknessand bentonite concentration to swell at its face and form across said path, where contacted by water, a water impervious barrier of swollen bentonite marging into a reserve mass of substantially unswollen bentonite.

11. The method of preventing flow or seepage of water through rigid structures susceptible to water penetration which comprises placing and supporting adjacent a side of such structure and across the path of water penetration a compact blanket including finely-divided, swellable bentonite and of sutficient thickness and bentonite concentration to swell at its face upon contact by the water and form across said path a water impervious barrier of swollen bentonite merging into swellable bentonite, and providing means adjacent the face of said blanket for holding the same in place.

12. A bulkhead or the like for preventing water flow through a determinate path comprising substantially rigid structures spaced apart and extending across the water path, said structures being susceptible to water penetration, and a compact mass of finely-divided bentonite, confined within the space between said structures.

13. A bulk head or the like for preventing water flow through a determinate path comprising substantially rigid structures spaced apart and extending across the water path, said structures being susceptible to water penetration, and a water-impervious mixture of finely-divided bentonite and sand confined within the space between said structures.

PAUL BECHI'NER.

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