US2709912A - Grout injection means in concrete structures - Google Patents

Description

June 7, 1955 a. CAPITAINE 2,709,912

GROUT INJECTION MEANS IN CONCRETE STRUCTURES Filed March 8, 1949 2 Sheets-Sheet 1- June 7, 1955 5. e. CAPITAINE GROUT INJECTION MEANS IN CONCRETE STRUCTURES Filed March 8, 1949 2 Sheets-Sheet 2 /IM I United States Patent 0 GROUT INJECTION MEANS IN CONCRETE STRUCTURES Emile G. Capitaine, Mauriac, France Application March 8, 1949, Serial No. 80,202

Claims priority, application France June 16, 1948 4 Claims. (Cl. 720.5)

Large scale concrete works-whether reinforced or not such as dams, works of art, revetted underground tunnels, underground reservoirs, etc., require to be cast in several joined blocks so as to avoid cracks which might be detrimental to imperviousness and general resistance.

Some time after the concrete has been cast, these blocks undergo contractions and contraction joints, provided for this purpose between them open up; the gap may reach 2 to 3 rant; in order to insure that the stresses are properly distributed throughout the mass of the concrete and that a suitable imperviousness is obtained, it is necessary to inject a cement grout under pressure into these contraction joints. After a further possible contraction of the concrete, it is even sometimes necessary to be able to inject additional grout into these joints to make up for subsequent reopening of the gaps. It is known that it has already been suggested-with this view in end-to provide, within the blocks of concrete and near the joints, feeds known as injection feeds that emerge here and there in joints and that are fitted at their ends, located in the plane of the joint considered with non-return valves for preventing rearward flow of the injected grout.

The idea has already been put forward of making these feeds out of tubes fitted, where necessary, with T-shaped branch pipes. The ends of these branch pipes that emerged into the joint were fitted in known structures with valves, each made up generally of a rubber washer, placed over the free-end of the tube and kept in place by a system of straps positioned outside the tube.

To prevent the liquid cement grout coming from an adjacent feed from jamming the valve and to allow two blocks that are joined together to contract without the straps being torn away, it has also been suggested to encase the valves and the stirrups with pockets of fine sand because this sand has the property of being impervious to the liquid grout;

In practice, this contrivance showed itself to be unreliable. Indeed, according to its grain composition, this sand is sometimes converted into concrete, thus definitely stopping the valve and preventing any injection of additional grout. Furthermore, the sand pockets were sometimes used to conceal defects in the execution. Finally, after the first injecion, the sand can no longer play its part as a protection. So that a later injecion of grout might be possible, it is necessary to clean the feeds out, after they have been used, to ensure that any cement that may have remained in them does not close them up.

But, by their very nature, the T-shaped branch pipes are difficult to clean. Some cement may remain at the end of the branch pipe in the neighbourhood of the valve and put the latter out of action. However a method is known of cleaning the feeds efficiently according to which they are jointed up in a circuit that emerges onto one given face of the work so that the water injected other.

through one end of the circuit comes out of the other. Nevertheless the difiiculty of cleaning the T-shaped branch pipes remains.

The object of the present invention is to improve the methods and means for injecting the contraction joints in large works. These improvements allow reliably executing several injections of the joints in succession.

According to a first object of the invention the T- shaped branch pipes that emerge out the joints carry inwardly a deflector that forces the water used for cleaning the feed to be urged into register with the branch pipe'so that the water may clean the inside of the latter and the internal face of the valve.

. According to another improvement, the valve itself is made of an elastic substance with internal cavities and bears against the opening of the branch pipe that emerges in the joint. This elastic valve is preferably provided with flanges that are placed over a stirrup carried by the branch pipe and this ensures its correct positioning.

It is preferable that the elastic substance in the immediate vicinity of the opening should be rendered rigid by the affixing of a flat piece so that this assembly can act as a valve, that is to say it can open over the entire circumference of the opening considered.

Furthermore, the general shape of this elastic valve is, preferably, that of a truncated cone so that, being forced by the pressure of injection, it fits closely at the bottom of the recess within which it is housed and prevents the injected liquid from entering the bottom of said recess. This truncated cone shape offers the further advantage of preventing the valve from being pulled out during the contraction of the blocks, this pulling out action being already neutralised by the non-adherence of the rubber to the concrete. If desired the valve may be coated with paraffin to reduce still further this adherence and to still better preserve the rubber. The description that follows and given out with reference to the attached drawing is of course given by way of a non-restrictive example, so as to clearly show how the invention can be executed in practice, the characteristic features appearing either in the drawing or specification forming of course, part of the said invention.

In said drawings:

Figure 1 is a diagrammatic vertical section of a large work in the vicinity of a contraction joint and it shows the layout of the injection feeds.

Fig. 2 is a section on a larger scale along line II-lt of Fig. 1 showing one of the T-shaped branch pipes of the feed.

Fig. 3 is a section along line III-III of Fig. 2.

Fig. 4 is a view similar to Fig. 2 showing the location of the injection feed on the shuttering of the Work before casting the first batch of concrete.

Fig. 5 is a longitudinal section of a valve according to the invention along line VV of Figure 6.

Fig. 6 is a plan view of a valve according to the invention. a

Fig. 7 is a side elevation view of the valve, the concrete mass and the end of the branch pipe being shown in section.

Work 1, some great dam for instance, shown in sec tion in Figure 1, is made up of blocks or vertical lumps of concrete that have been cast in contact with one an- In the vicinity of the vertical plane where the two blocks meet there are arranged injection feeds with openings that carry valves and that emerge in the plane of the contraction joint; the vertical distance between two feeds is a few meters and the space between two valves on any one feed is of the same order of magnitude.

In the example disclosed, feed 2 is made up of a tube that enters the work at A on the downstream side therefinally at B.

of; the tube slopes slightly upwards, then bends in a vertical pla. e, follows a slightly downward course and emerges Branch pipes 3 that are T-shaped register with the substantially horizontal portions to allow for injection into the plane of the joint.

To inject grout into the joint, after end B has been blocked up, all that is required is to make the cement grout advance under pressure from end A.

As shown in the drawings, it is preferable to use a three way cock 23 (Fig. 1), the inner plug 23 of which enables, alternately, the grout entering the channel 24, to flow into either end of feed 2, the other one being blocked up. Connection is made with the feeds by means of flexible pipes.

The direction of injection is reversed periodically, say every half hour, to prevent any cement from accumulating in the feed.

When the injection is over, the washing out of the feed is carried out by making a stream of water run through the feed under pressure; the water enters through one of the extremities of the feed and leaves through the other. The water can be completely removed because of the downward slope of the feed towards the downstream facing of the work. But it might happen that notwithstanding the washing, some cement remains within the branch pipes 3 and this would prevent any subsequent injection. In the T-shaped branch pipe, shown in Fig. 2, that opens into the joint 4 and is closed by valve 5 to be described later, a deflector 6 has been arranged to oblige the water used for washing out to follow the course 7, that is to say, to come and swirl around in the vicinity of face 5a of valve 5; the cement grout that is injected under pressure also follows this course without difficulty due to the high pressures that are in operation. Valve 5, shown in greater detail in Figures 5 and 6, is made up of a rubber mass in the general shape of a frusto-cone and carries lugs or flanges 8 for fixing it to the terminal stirrup-shaped lugs 21 of the T-shaped branch pipe.

This rubber mass includes a void part 9 that is filled advantageously by a core of sponge rubber 10 to make the moulding of the valve easier. The valve is reinforced in its lower portion by means of a fiat metallic washer 11 and in its upper portion by means of a second washer 12 of the same type. These washers make the two opposite faces of the frusto-cones rigid so that the valve can loose its shape only by crushing along the axis of the frusto-cone. This crushing is made possible by the presence of interior empty spaces; it is well known a as a matter of fact that elastic substances such as rubber, may loose their shape but are practically incompressible. Furthermore, the Washer 11 forces the valve to open and thereby uncover the entire periphery of the opening of the branch tube 3.

The plane of the lugs 13 through which the flanges 3, and 21 are in contact is located slightly behind the plane 14- of the surface through which the valve rests on the terminal surface of the branch tube. By reason of this arrangement, the valve is given a slight initial deformation when it is being fitted in position and this prevents it from opening for small pressures such as that used for the washing water.

Consequently, the valve allows only the grouting to enter the joint said grouting being submitted to a pressure varying from 2 to 10 kgs., for instance, but not the volume of water the pressure of which is of the order of 1.5 kgs. per sq. cm.

To rig up the feed 2, branch tubes 3 and the valve 5 in a work that is being erected, the procedure outlined hereinafter with reference to Figure 4 is carried out.

The lugs or flanges 21 are covered over by a rubber flap or shutter 15 that is placed and pressed against shuttering 16 by means of bindings 17 that keep feed 2 at a suitable distance away from the shuttering 16 and that prevents the cement from entering the feed and the threaded holes that are to secure the valve in position. The concrete is then poured through 18 into the shuttering. After setting and hardening, the shuttering is dismantled and in its place the valve 5 is fixed by means of screws 19, said valve being if required previously coated with paraffin. The block that is adjacent to the one that has just been cast can then be cast in its turn in cont act with the first. The valves are embedded directly in the cement of this second block with no further precaution being necessary. After some time has elapsed, the plane of joint 4 between the two blocks opens out as a consequence of the contraction of the cement of each of the said blocks; the injection of the joint is then carried out in the manner described with reference to Fig. 1.

In this operation, as shown in Fig. 7, valve 5 is crushed in the direction of axis by a certain length d. The magnitude of this crushing action, which is a function of the size of the open spaces in the valve, is chosen such that it is always greater than the maximum possible gap at the joint.

Thus, following an initial contraction, a layer 20 of the cement grout may be injected, its thickness being less than a; in the second injection, which may follow the first one it remains possible to introduce some cement grout into space 20a, the sum of thicknesses 2i) and 20:; being assumed to be less than the valve opening movement.

Furthermore, it will he noticed that, in these injection operations, the frusto-conical portion of the valve comes and fits tightly in the housing it has made for itself in the concrete, during the casting of the second block adjacent the first one. So, by filling said recess under pressure, the frusto-conical valve portion prevents the injected cement from entering said recess which could, eventually, be detrimental to the compressibility of the valve. On the other hand, during the contraction, this frusto-conical portion may easily become unstuck with reference to the concrete of the second block when, as a consequence of the concrete contracting, the two blocks draw apart in such a way that the valve cannot be ripped off as was the case when the valves were held by metal straps.

Obviously many modifications can be introduced into the improved arrangements that have been described, particularly through the incorporation of equivalent technical means, without for that reason unduly widening the principles of the invention as defined in accompanying claims.

What I claim is:

1. In a structure made of separately formed concrete blocks, a grouting device comprising a grout supply pipe in one of said blocks and having a discharge orifice facing an adjacent block, and a pressure-responsive valve disposed at said orifice and including a body of yielding material having a face in covering relation to the orifice for normally closing the orifice, and for opening it in response to the persence of grout pressure in the pipe, said body freely engaging said adjacent block, and means mounting the body at the orifice, said body and its said face being yieldaole away from the orifice in response to grout pressure exerted on the face and resiliently and automatically returnable to obturating position upon release of the grout pressure, said body tapering outwardly, toward the adjacent block.

2. A device as claimed in claim 1, wherein said body is formed of rubber and compressible in the direction of said adjacent block and has a cavity, said cavity being filled with multicellular yielding material.

3. A device as claimed in claim 2, wherein said mounting means includes integral cars radially extending tom the body in a plane located slightly behind the plane of said face and means attaching said ears to the pipe with the face covering the orifice so that the body is given a slight initial deformation.

4. A device as claimed in claim 3, wherein stiffening members are disposed in the body paralleling the said 2,188,938 Brown et a1. Feb. 6, 1940 face thereof. 2,204,006 Allen et a1 June 11, 1940 2,246,028 Woodring June 17, 1941 References Cited In the file of this patent 2 333 2 Smith at Nov 9 194 UNITED STATES PATENTS 5 11,011 Troiel NOV. 12, 1946 1,628,933 Troiel May 17, 1927 FOREIGN PATENTS 1,726,414 Savage 27, 1929 272,5 Great i i of 1927 2,187,324 Many Jan. 16, 1940

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