US2434302A - Method of solidifying porous structures - Google Patents

Description

No Drawing.

W The present invention relates to a process of,

tains afidic colloidal silicET In t e prac ce 0 e nvention as therein dereinforcing and-solidifying porous masses, such as. porous concrete, roc masonry, pieces of packed aggregate and the like, which includes forcing an improved fiowable or intrusion compo- 8 sition into the void spaces of such porous masses to increase their strength and water-tightness.

This application is a continuatio art of v a my prior application Seria 1,543, filed May 1 2, 1941, now abandoned.

--Irrmy Patent 2,254,252 I disclosed a method for densifying and solidifying porous masses ofearth, masonry, concrete structures and the like by forcing under pressure into the voids and in Q terstices of the porous mass an aqueous slurry 1 having an hydraulic cement, such as Portland clemepgin suspension, and containing suspens on solubleand insoluble ingredients, particularly a finely diyideglilling material which conscribed, the porous structure which may for example be a dam, bridge, pier or the like, is drilled and the intrusion material is forced through a nozzle inserted in the drilled hole. It has been found that it frequently migrates great distances from the nozzle, which distances are often as much as thirty or forty feet, or even more. Even though there is a very substantial pressure applid to the intrusion material passing through the nozzle, this pressure may be largely dissipated or used up by friction of the material on the walls of the passageway. so that in areas sub stantally removed. from the nozzle it becomes diilicult to force the material into many of such remote, finer voids and crevices. While the process greatly improves the strength of the structures and permits the densifying and rejuvenation of dams and the like, it is desirable and it is an object of the present invention to provide a process which will readily fill even the relatively fine voids at great distances from the nozzle, so

.that even greater improvement in density and strength may be obtained.

s, PATE T, OFFICE 2,434,302 Y, Mn'rnop or soammmc. ronous sraucmas Louis s. Wertz, Cleveland Heights, 01116 Application July 22, 1942, Serial No. 451,959

scieimeyicici-ssi between the pieces of aggregate and into voids of the structure adjacent or communicating with 7 the cavity. I

It is an object of the present invention to provide a composition for and method of repairing and filling concrete, masonry structures and the like, as disclosed in my above-mentioned patent and applications; in which the repair material will have even less tendency to shrink and will 10 make a stronger bond with the structure being repaired or with the pieces of aggregate than was previously possible. 1 A further object of the present invention is to provide a method of patching surface cavities in.

concrete structures wherein the patch has substantially no tendency toward shrinkage from the walls of the structure and wherein an excellent bond over the whole area is produced.

' Another object of the present invention is to provide of method of constructing concrete structures wherein less cement is used than is required by methods heretofore proposed and wherein a stronger structure of relatively low shrinkage is produced.

A further object of the present invention is to provide a har'denable intrusion material containing an hydraulic cement as the principal bonding ingredient which may be pumped through porous concrete having only fine passageways therein with substantially no tendency'for settling or plugging of the passageways and which,

when mixed with aggregate and pumped into a completely enclosed space, will form concrete of superior strength.

Other objects and advantages will be apparent from the following detailed description of the invention.

It has now been found that when the aqueous slurry which is forced into the structure or between particles of. aggregate within a closed cavity, as described in my above-mentioned application, contains a relatively small amount of aluminum powder it penetrates into the smaller voids of the structure located at substantial dis- In my application Serial No. 321,222, filed Febt n om the noz le: if a re a e is pac ed ruary 28, 1940, now Patent 2,313,110, granted March 9, 1943, is disclosed a' method of construction and a method for filling cavities or disintegrated areas in communication with the surface within a closed form or cavity, it penetrates into the finer crevices between aggregate particles in the enclosed cavity. Structures thus treated have greatly improved strength and the material has of structures by defining the cavity or space with to ial y no tendency to shrin away from a form, substantially filling the cavity within the form with loose aggregate, and forcing the intrusion material, such as that disclosed in my Patent 2,254,252, which may include a substanthe walls of the cavities.

It has also been found in accordancewith the present invention that structures of exceptionally high strength and low-shrinkage tendencies may tial amount of relatively fine sand, into the cavity 56 be efficiently produced by forcing between pieces of aggregate, preferably in a space defined by forms, the above hardenable slurry or grout containing aluminum powder, with or without-sand, etc. The maximum size of the filler or even sand is dependent on the size of the ag regate used. The size should be sufficiently small to prevent blocking of the voids and passageways therein. Relatively fine sand such as that having a fineness modulus up to about 2 or so is usually preferred. When the voids between parts of the structure or between aggregate are relatively large, some coarser sand may be used.

The grout or the intrusion material preferably should contain an hydraulic cement, such as Portland cement, a finely divided filling material which contains some acidic olloidal silica, a small amount of lubricating agent? ga as-producing metal powder. which preferably is aluminum powder. and sufilcient water to form a slurry. The grout may also contain substantial quantities of sand, which is especially desirable for solidification of loose aggregate or the pre-coated aggregate described in my application Serial No. 4 41,598. filed May 4, 1942, now abandoned.

Examples of the most desirable filling materials are fly ash, blast furnace slag, other finely divided siliceous materials and certain natural siliceous materials, such as trass. pumicite, diatomaceous earths, etc., generally classified as pozzolanas,"

which form compounds having considerable ce-' mentitious value with lime that may be liberated as a by-product during the hardening of the cement. Some types of blast furnaces slag are hydraulically active in themselves and are very desirable. Ground limestone may also be used to some extent. For the solidification of structures with relatively fine voids. the filling material should be ground sumciently fine so that substantially all of'it will pass through a IOU-mesh screen and preferably most of it should pass a 200-mesh screen.

For the repair of surface cavities in structures, in the construction of structures utilizing loose aggregate, and'in the solidification of structures with larger voids, a substantial quantity of sand or its equivalent may frequently be used. The

sand preferably is relatively line. In some instances, where the voids are large, sand may be used in place of a large proportion of the finely ground filler. Some filler'containing. acidic colloidal silica should be present, however, to retard the gelation of the cement.

v The quantity of finely divided siliceous materials or filler used will depend upon the character and qualities desired in the required slurry and hardened cement. Usually the siliceous materials and cement may be used advantageously in about equal proportions. The range of proportions of filler, excludingsand, to cement may vary widely from approximately one part of filler to two parts of cement, to about equal proportions of filler and cement, or even about two parts of filler to one oi cement. In addition to such filler, sand may be present in amounts up to three or four parts by weight to one part of cement. Usually the sand is present in amounts between one-half to about two and one-half parts by weight to one of cement. The greatest strength is obtained in the lower portion of this range, i. e. when the amount of filler is about equal to or even less than the amount of cement. In the filling of rel- The lubricating agent may be any of the oleaginous materials which preferably do not undergo any appreciable reaction with the ingredients of the cement composition or, at least, do not react with the cement at appreciable speed to destroy the oily properties of the lubricant. Examples of lubricants are mineral oils, st r such as ammonium stearates, sodium stearate, vegetable oils, particularly sulphonated vegetable oils such as sulphonated coconut oil or peanut oil, and mixtures of such materials, A particularly desirable lubricating material comprises about 20% to of a light mineral oil, which is preferably lighter than lubricating grades, and 50 to 80% or more of a solution or emulsion of a stearate, suchas an emulsified ammonium stearate containing about two-thirds water and one-third solid ammonium stearate. These materials reduce the friction within the voids or passageways of a structure, or between the particles or the aggregate and, to some extent, delay and retard the setting of the cement so that gelling or setting does not take place until the slurry is placed.

The quantity of lubricating agent may be varied considerably and is varied according to the fineness of the voids in the structure or the fineness of the aggregate used. When the cavities in the structures to be repaired are composed substantially of relatively fine voids, a much larger quantity of lubricating agent should be present than when the structure is composed of relatively coarse voids. Usually, the quantity of lubricant high frictional resistance, and as little as .1%, by *weight, is sometimes satisfactory for porous structures having coarser voids.

The gas-producing metallic powder is preferably finely divided aluminum. Aluminum reacts relatively rapidly and is more eilective than are metals-such as iron and zinc, which appear to be I and the temperature of the mix.

ct little value. The metal powder should be preferably be present in the amount of about .01% to about 's02% or even .025% of the weight of the cement. When the quantity of aluminum powder is much less than .005% of the weight of-the cement, most of the desirable effects incident to its use are not secured. When the quantity of aluminum powder is greater than .04% or .05%, the quantity of gas produced within the material may be so great that increased porosity and decrease in strength result. The optimum quantity of aluminum powder varies for the type of cement {used and is dependent to a considerable extent on the amount of alkali present in the cement It seldom, if ever, is higher than .03% of the weight of the cement, however.

If the cement contains a amount of alkali, the reaction between the aluminum and the alkali is carried on at a rela tively slow rate and less gas will be lost during a the mixing'process, so that a smaller amount of aluminum powder may usually be present. The

- cement should have enough alkali to develop a atively small holes where strength is not a prime consideration, the ratio of filler to cement may gas, but it is undesirable that gas develop during the mixing to any appreciable extent. It is very important that the gas-producing reaction be suiliciently retarded that it takes place almost entirely after-the concrete has been placed or pumped within the cavities or interstices of the structure. A suillcient amount of retarder or relatively small slurry has been placed, and to also retard the set-f ting of the cement until the concrete has been placed and the gas-producing reaction is substantially complete. The development of gas can also be controlled by the use of metal powder or larger or smaller particles or by coating the metal'with a delaying material. such as an oil or stearate. Larger particles or partially coated particles react slower than do finer particles of the same metal.

The above-mentioned oleaginous material perform both of these functions and in the mixing of the ingredients of the slurry, the metal powder is preferably first mixed with the retarder. such as a stearate, mineral oil, etc.. before it is mixedwith the cement. In this manner the aluminum powder is more readily dispersed and the particles are coated with sufllcient of the retarder to prevent the gas reaction from taking place during the mixing.

The following examples illustrate the present invention:

Example 1 A slurry was prepared by mixing two bags of cement (about 188 lbs). one bag (about 100 lbs.)

4 Example 3 The composition of Example 1 was forced into a porous structure in the manner disclosed in of a filling material such as finely ground, waterquenched blast furnace slag, or fiy ash-,ione quart .(about 2.3 lbs.) of lubricating agent, consisting of an emulsion containing about 33 Lammonium stearate, .035 of a pound of aluminurn'powder and suiflcient water to prepare a fiowable but somewhat viscous slurry. In the preparation of the slurry the aluminum powder was thoroughly mixed with the ammonium stearate and then added in a suitable mixer to the cement, filler and water. This slurry was then pumped into surface cavities of a concrete structure and maintained'under pressure. The cavities were filled with tightly packed aggregate, -and completely enclosed by a form and the solid walls of the structure. as described in my previously men-v tioned application, Serial No. 321,222. The forms were removed from the cavity after the slurry had set and hardened or cured, and an examination showed that there was no observable shrinkage between the edges of the patch and the solid portions of the structure. and that the patch was bonded to the structure with exceedingly great strength.

Example 2 a slurry similar to that described in Example 49 agent which increases fiowabiiity of the slurry.

quantity of packed pieces of aggregate. The

amount of slurry pumped therein was sufiicient to completely fill the residual space of each container. In the closed container a pressure of thirty lbs. was developed; whereas in the'open container the pressure was obviously atmospheric. The concrete was. in both cases, allowed .to harden and cure under like conditions of temperature and humidity, which prevented loss of water. After several days both were tested for their compressive strengths. The concrete prepared in the closed contained had a substantially higher compressive strength than had the concrete prepared in the open container.

my Patent 2,254,252, above-mentioned. Core samples removed from the structure showed a' compressivostrength much higher than. those cores removed from the same relative positions of structures repaired by method heretofore used. They also showed improved penetration at great distances from the nozzle.

The composition of applicant's invention may be used for the solidification of earth, rock, gravel, strata. concrete. such as are present at dams or building sites. as well as for the patching and repairing of concrete structures. It has been found that when the material is sufilciently enclosed for a substantial pressure to be developed due to gas reaction, the finer pores within the cavity or separating the aggregate are more completely filled, the intrusion material migrates substantially greater distances. and a structure of improved strength is produced and resistance to the elements is obtained.

It is to be understood that the particular prodnot shown and described and the particular pro cedure set forth arepresented ior purposes of explanation and illustration. and that various modifications can be made without departingfrom my invention as defined in the appended claims.

fined by a, form, preparing a fiowa'ble. solidifiable aqueous slurry containing finely divided hydraulic cement, sand, finely divided aluminum, a finely divided filling material containingacidic colloidal silica and capable of retarding gelatin of said cement and an oleaginous lubricating said finely divided aluminum being present in an amount between about OO5% and about .05% or the weight of the cement, forcing the aqueous slurry into said area defined by said form between the voids and interstices of pieces of gre'gate therein and allowing the slurry to t. whereby a concrete structure of relatively-high strength and relatively low shrinkage is produced.

2. A process or construction which comprises incorporating loose aggregate into an area defined by a form, preparing a fiowable, solidifiable aqueous slurry containing finely divided hydraulic cement. sand. finely divided alumium, a finely divided filling material containing acidic colliodal silica and capable of retarding gelatin of said a about .005% and about .05% of the weight of the cement. forcing the aqueous slurry into said area defined by said iorm between the-voids and interstices of pieces of aggregate therein and allowing the slurry to set, whereby a concrete structure of relatively .high strength and relatively low shrinkage is produced.

3. A process for filling voids and interstices in porous masses which comprises forming a readily flowable aqueous slurry containing in suspension a hydraulic cement, acidic colloidal silica to retard gelation or the cement, a lubricating agent which increases fiowability of the slurry and .005% to .05%, based on the weight of the cement, or finely divided aluminum. forcing the aqueous slurry into the voids and interstices of 76 the porous masses and allowing the slurry to gel 7' and set therein, whereby the porous masses are substantially strengthened and solidified.

4. A process for filling voids and interstices in porous masses which comprises forming a readily fiowable aqueous slurry containing in suspensio a hydraulic cement, acidiecolloidal silica to retard gelation of the cement, a fatty acid salt and .005% to 35%, based on the weight of the cement, of finely divided aluminum, forcing the aqueous slurry into the voids and interstices of the porous masses and allowing the slurry to gel and set therein,'whereby the porous masses are substantially strengthened and solidified 5. A process for filling voids and interstices in porous masses which comprises forming a readily fiowabie aqueous slurry containing in suspension a hydraulic cement, acidic colloidal silica to retard gelation of the cement, a stearate, a mineral oil and .005% to .05%, based on the weight 01- the cement, oi finely divided aluminum, forcing the aqueous slurry into the voids and interstices of the porous masses and, allowing the slurry to gel and set therein, whereby the porous masses are substantially strengthened and solidified.

6. A process for filling voids and interstices in porous masses which comprises formin an aqueous slurry containing in suspension a hydraulic cement, acidic colloidal silica to retard gelation o! the cement, ammonium stearate, a mineral oil to increase the fiowabllity 01' said slurry, and aluminum powder in an amount up to .05% ot the weight of the cement, forcing the aqueous slurry into the voids and interstices of the porous masses and allowing the slurry to gel and set therein, whereby the porous masses are substantially strengthened and solidified.

7. A process for filling voids and interstices in porous masses which comprises a readily fiowable, aqueous slurry containing in suspension finelv divided Portland cement. a finely divided filling material in an amount up to twice the weight of the cement, saidfilling material containing acidic colloidal silica to retard gelation of the cement,

a lubricating agent to increase the fiowability of 5 the slurry, and finelyrdivided aluminum in an amount up to .05% 01' the weight oi the cement. forcing the aqueous slurry into the voids and interstices ot the porous masses and allowing the slurry to gel and set therein, whereby the porous masses are substantially strengthened and solidified.

8. A process of construction which comprises inenrporating aggregate into an area defined by a form, packing the aggregate therein, preparing a fiowable, solidifiable, aqueous slurry con-- taining finely divided Portland cement, sand in an amount up to twice the weight of the cement,

' finely divided aluminum in an amount up to .05%

file of this patent:

01' the weight or the cement, a finely divided inorganic filling material in an amount up to twice the weight of the cement, said filling material containing acidic colloidal silica and being capable oi retarding gelation or the cement, and a lubricating agent to increase the fiowability oi the slurry, forcing the aqueous slurry into said area defined by said form between the voids and interstices of pieces of ag regate therein and allowing the slurry to set, whereby a concrete structure or relatively high strength and relatively low shrinkage is produced;

LOUIS S. WERTZ.

REFERENCES crrsn The following references are '0! record in v UNITED STATES PATENTS Great Britain 1936 his,

Patent No. 2,434,302;

Certificate Correction 'January13, 1948. LOUIS S. WERTZ It is hereby certified that error appears in the printed s ecification of the above numbered patent requiring correction as follows: Column 6, ine 39, claim 1, and line 56, claim 2, for the word gelatin read gelation; and that the said LettersPatent should be read with this correction therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 23rd day of March, A. D. 1948.

f THOMAS F. MURPHY,

- Assistant Uqmmz'ssz'oner of Patents.