GB2207945A

GB2207945A - Repairing cracks in concrete

Info

Publication number: GB2207945A
Application number: GB08719328A
Authority: GB
Inventors: Tsutomu Matsuo; Masakazu Kusunoki
Original assignee: Konishi Co Ltd
Current assignee: Konishi Co Ltd
Priority date: 1987-08-14
Filing date: 1987-08-14
Publication date: 1989-02-15
Anticipated expiration: 2007-08-14
Also published as: GB2207945B; GB8719328D0

Abstract

A method of injecting or pouring crack filling material into a crack in a concrete or stone structure by forming a sealing layer with spaced holes over the crack, attaching injection pipes over the holes in the sealing layer and injecting crack filling adhesive through the injection pipe and into the crack. Once the adhesive has hardened the sealing layer is broken off. <IMAGE>

Description

REPAIR OF CRACKS IN CONCRETE, STONE OR SIMILAR MATERIALS This invention relates to the repair of cracks in concrete, stone or similar materials. In particular the invention relates to a method of repairing a crack by injecting or pouring adhesives into the crack.

Cracks in concrete and stone are commonly repaired by filling the cracks with an adhesive.

Very often this adhesive is an epoxy resin.

One known method of filling a crack with adhesive involves the use of injection pipes. Each pipe has an integral, relatively wide, flange at one end which forms a flat base; the diameter of this flange is usually several times the outside diameter of the pipe. The base of the flange is thickly coated with adhesive and stuck onto the concrete surrounding the crack thus fixing the pipe to the concrete structure. The hollow end of the pipe should at least partly cover the crack.

Adhesive can then be injected or poured into the pipe until the crack is full thus filling and repairing the crack. There are several disadvantages with this method. When the flange is glued onto the structure large amounts of adhesive are often used and this adhesive tends to run prior to it solidifying so that it can block both the outside of the crack and also seal the end of the pipe nearest to the flange. If part of the crack nearest the surface of the concrete, or the end of the pipe becomes blocked or partly blocked it is then difficult to inject adhesive into the crack to fill the crack.

A second disadvantage is that the flanges of the pipe are so well bonded to the structure that they are difficult to remove once the crack has been filled. This is particularly true if an epoxy or acrylic resin is used as the adhesive material.

An object of the present invention is to minimise the amount of adhesive agent remaining on the surface of concrete structures when cracks in these structures are filled.

According to the present invention there is provided a method of repairing a crack in concrete, stone or similar materials comprising the steps of locating or forming a layer of inorganic material over the region of said crack, said layer being provided with one or more holes communicating with said crack, attaching one or more port means to said layer so that each'is in communication with a said hole and injecting suitable crack filling material through the or each port means into the crack.

Advantages of the present invention over the prior art are as follows. The intermediate layer, made of non-organic material, is easy to detach from the structure since it is relatively brittle and will break on impact with, for example, a hammer. There is very little adhesive resin left on the surface of the structure; surplus adhesive resin only occurs where the holes of the intermediate sealing layer were, before the layer was removed.

Having holes in an intermediate layer with the holes having a larger diameter than the diameter of injection pipe provides an area of injection pipe flange for surplus adhesive to collect on and this prevents the adhesive blocking the end of the pipe.

In a preferred form of the invention: (a) The sealing layer is made of non-organic material (b) The openings in this layer are of a larger diameter than the inside diameter of injection port means.

(c) The injection port means are attached to the outside of the openings When the injection pipes are fixed with adhesives onto the outside of the openings on the sealing layer, the injection pipes can be positioned easily at the upper part of the cracks because the diameter of the seal openings is larger than the inside diameter of the injection pipes. Moreover, the adhesives are not deposited directly onto the structure to be repaired.

Once the adhesive agent is poured into the cracks, therefore, no resin nor any adhesive agent is left on the structure except for the adhesive agent poured into the cracks hardened and deposited in the openings of the sealing layer A feature of the invention is that almost no adhesive agent is left on the structure, hence the seals can be removed after pouring adhesives into the cracks simply by striking with a hammer and only the adhesive agent left in the sealing layer openings is to be removed, which is advantageous in that surface finish is very easy.As the injection pipes are fixed onto the outside of the sealing layer openings, the adhesive agent applied to the back side of the bases of the injection pipes is left only around the seal openings even when it moves toward the center, which is advantageous in that the pipes and the cracks are never blocked and that clear inlets for adhesives are ensured for smooth flow.

The sealing agent of non-organic type may be a polymer cement, e.g. a cement with epoxy resin compund or liquid glass cement.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing which is a sectional view of a polymer cement layer covering a crack in -a concrete structure, with injection pipes attached to the layer, the section being taken along the length of the crack.

Referring to the drawing, at 1, is shown a portion of a concrete structure which has a crack, 2, running through it. A sealing layer of inorganic sealant 3, is attached to the flat surface of the structure surrounding the crack such that the layer covers the crack 2. The layer, 3, is formed from solidified polymer cement and its internal surface is coplanar with the flat surface of the structure 1.

The sealing layer has a series of circular through holes, 4. Injection pipes, 5, are attached to the exterior surface of the layer 3. Each injection pipe, 5, comprises a cylindrical pipe, 6, which is formed integrally with an annular flange, 7. Each flange is located adjacent the layer 3 and secured thereto by adhesive 8 of the epoxy resin type.

The diameter of each hole, 4, in the sealing layer is greater than the inside diameter, 5A, of each pipe, 6.

The sealing layer 3, and holes 4, are formed as follows. Cylindrical moulds, not shown are placed over the crack, 2. A layer of polymer cement is then applied over the crack and around the cylindrical moulds. Once the polymer cement has solidified the cylindrical moulds are removed to leave a series of holes 4, in the layer 3. The distance between the holes, 4, is greater than the diameter of the injection pipe flanges.

Once the sealing layer, 3, has been formed as described the injection pipes, 5, are glued in position over the holes, 4, with the epoxy resin adhesive, 8. Since the inside diameter of the pipes 6, is less than the diameter of the holes, any surplus adhesive, 8a, collects on the surface of the flange 7a, next to the entrance to the pipe 5a, instead of blocking the end of the injection pipe 5.

After the adhesive 8, has hardened a nozzle of an injection device, not shown, is connected to the injection pipe 6, and an adhesive agent not shown, is injected or poured into the crack, 2, via the injection pipe and intermediate layer,3. The crack then becomes filled with the adhesive agent.

The pipe, 6, is then closed. When the adhesive agent in the crack has hardened and cured, the seal is removed by striking it with a hammer. A smooth surface is then left apart from a series of protrusions of adhesive agent where the holes, 4, originally were. These protrusions can be removed with sandpaper to leave a smooth surface.

Various materials may be used to form the sealing layer such as polymer cement, for example, silicone based cement or liquid glass cement. Various other embodiments are within the scope of the present invention. A solid sealing layer can be made with suitably sized and located holes and fixed over the crack rather than forming the sealing layer in situ' over the crack. The layer may be removed intact for re-use rather than being broken off the surface.

Claims

1. A method of repairing a crack in concrete stone or similar materials comprising the steps of locating or forming a layer of inorganic material over the region of said crack, said layer being provided with one or more holes communicating with said crack, attaching one or more port means to said layer so that each is in communication with a said hole and injecting suitable crack filling material through the or each port means into the crack.

2. A method as claimed in claim one wherein the port means are injection pipes provided with flanges said flanges being attached by adhesive to said layer.

3. A method as claimed in claim 2 wherein the diameter of the or each hole in the layer is greater than the diameter of the or each injection pipe.

4. A method as claimed in claim 1, 2, or 3 wherein the intermediate sealing layer is formed in situ using a polymer resin or glass polymer type resin or other suitable solidifying sealing material.

5. A method substantially as hereinbefore described with reference to the accompanying drawing.

5. A method as claimed in claim 1, 2 or 3 where the intermediate sealing layer is pre-formed and is then located over the crack.

6. A method substantially as hereinbefore described with reference to the accompanying drawing.

Amendments to the claims have been filed as follows 1. A method of repairing a crack in concrete stone or similar materials comprising the steps of locating or forming a layer of inorganic material over the region of said crack, said layer being provided with one or more holes communicating with said crack, attaching one or more port means to said layer so that each is in communication with a said hole, the diameter of the or each hole in the layer being greater than the diameter of the or each injection pipe, and injecting suitable crack filling material through the or each port means into the crack.

3. A method as claimed in claim 1, or claim 2, wherein the intermediate sealing layer is formed in situ using a polymer resin or glass polymer type resin or other suitable solidifying sealing material.

4. A method as claimed in claim 1, or claim 2, wherein the intermediate sealing layer is pre-formed and is then located over the crack.