GB2206370A

GB2206370A - Repairing artificial and natural structures

Info

Publication number: GB2206370A
Application number: GB08814399A
Authority: GB
Inventors: I Hag
Original assignee: BICC PLC
Current assignee: Balfour Beatty PLC
Priority date: 1987-06-17
Filing date: 1988-06-17
Publication date: 1989-01-05
Anticipated expiration: 2008-06-17
Also published as: GB2206370B; GB8714161D0; GB8814399D0

Abstract

In an inexpensive method of filling a cavity 3 opening in a cavity 2 of an artificial or natural structure 1 (or into a surface which is vertical or is inclined at any acute angle), a rigid shutter 4 is applied over the cavity and secured to the structure 2 and is sealed to the structure to form a fluid-tight enclosure. A coarse aggregate 6 is blown into the cavity 3 through a pipe 5 passing through the shutter 4 until the cavity is substantially filled with the aggregate, the weight of the aggregate at least in part being supported by the shutter. Air and any other fluid are evacuated from the cavity 3 and a cement grout is allowed to be drawn into the cavity through a second pipe 7 passing through the shutter 4 to fill the interstices between the aggregate. The cement grout is then permitted to set and bond to the surface bounding the cavity 3 and to the surfaces of the aggregate 6 and, after the cement grout has set, the shutter 4 is removed. The filled cavity 3 has a strength substantially matching that of the structure 1 itself. <IMAGE>

Description

IMPROVEMENTS RELATING TO ARTIFICIAL AND NATURAL STRUCTURES This invention relates to artificial and natural structures built up of or comprising a plurality of separately formed bodies of manufactured or natural material or consisting of a single body of concrete or of rock, granite or other material in its natural state.

Structures fabricated from or comprising a plurality of separately formed bodies include the walls of buildings, bridges and their abutments and piers, tunnels, brick-lined drains and sewers, retaining walls, monuments, sculptures, archaeological remains, and other structures built up of or comprising bricks, rocks, stones, granite or other building materials with or without interposed mortar or other hardenable material.

Single bodies of concrete or other materials include bridges, tunnels and other artificial structures having a soffitt or underlying surface. All such artificial and natural structures will, for convenience, hereinafter be referred to as "artificial or natural structures of the kind specified".

It is an object of the invention to provide an improved method of filling a cavity opening into a surface of an artificial or natural structure of the kind specified, which surface is substantially horizontal and underlies the structure, is substantially vertical or is inclined at any acute angle therebetween.

According to the invention the method comprises applying over the cavity and securing to said surface of the structure bounding the cavity a substantially rigid shutter and sealing the shutter to the structure in such a way as to form a substantially fluid-tight enclosure; introducing into the cavity through a pipe passing through the shutter a multiplicity of separate bodies of solid material in its natural state and/or of concrete or other material in a manufactured solid state until the cavity is substantially filled with said bodies, the weight of the bodies at least in part being supported by the rigid shutter; evacuating air and any other fluid from the cavity; allowing hardenable material in a liquid or semi-liquid state to be drawn into the cavity and to fill the interstices between the separate bodies; and permitting the hardenable material to set and bond firmly to the surface bounding the cavity and the surfaces of the separate solid bodies.

Preferably, after the hardenable material has set, the rigid shutter is removed.

To facilitate formation of the substantially fluid-tight enclosure, the rigid shutter may be formed of a fluid-impermeable material or a flexible covering of fluid-impermeable material, e.g. a flexible sheet of plastics material, may be applied over the outer surface of the shutter and sealed to the surface of the structure bounding the cavity. The shutter is preferably in the form of a substantially rigid sheet of plywood or other suitable fluid-impermeable material.

The pipe through which the solid bodies are introduced into the cavity preferably so protrudes through the shutter into the cavity that its open end in the cavity is at or close to the highest point in the cavity so that the risk that the solid bodies, when introduced, may impede introduction of further solid bodies is substantially reduced. The multiplicity of solid bodies preferably is blown through the pipe into the cavity by air under pressure. The pipe through which solid bodies are introduced into the cavity may also be used for the evacuation of air and other fluid from the cavity.

Preferably, the hardenable material in a liquid or semi-liquid state is drawn into the cavity through a second pipe which preferably passes through the shutter into the cavity so that its open end in the cavity is at or near the lowest point of the cavity and, to restrain solid bodies from entering this pipe, preferably the open end of the pipe within the cavity is covered by a mesh with holes of appropriately small size.

Preferably, all air and other fluid is substantially evacuated from the cavity before the hardenable material is introduced therein.

The multiplicity of separate solid bodies is preferably in the form of a coarse aggregate, gravel being preferred because of its flow properties but, in some circumstances, stone or granite chippings may be employed.

The harden able material may be a cement grout or it may be a hardenable mixture of cold setting synthetic resin in a liquid or semi-liquid state and a filler.

When a hardenable mixture of cold setting synthetic resin in a liquid or semi-liquid state and a filler is used, preferably the multiplicity of solid bodies is in the form of a fine aggregate.

The improved method of the present invention enables a cavity in a surface of an artificial or natural structure of the kind specified, the surface being substantially horizontal, being substantially vertical or being inclined at any acute angle therebetween, to be completely filled with a combination of solid bodies and hardenable material and the filled cavity to have a strength substantially matching that of the structure itself. Furthermore, by initially substantially filling the cavity with solid bodies, the quantity of harden able material to be used is substantially less than would otherwise be the case thus reducing the cost of the repair - and the risk of cracking due to shrinkage is also reduced.

The invention is further illustrated by a description, by way of example, of the preferred method of filling a cavity in a soffitt of an artificial structure and of the preferred method of filling a cavity in a surface of a vertical wall of an artificial structure, with reference to the accompanying drawing, in which: Figure 1 is a schematic view of the arrangement for filling a cavity in a soffitt of an artificial structure, and Figure 2 is a similar view of the arrangement for filling a cavity in a surface of a vertical wall of an artificial structure.

Referring to Figure 1, an artificial structure 1 has a soffitt 2 in which is a cavity 3 opening into the soffitt. In order to fill the cavity 3, a rigid sheet 4 of plywood is applied over the cavity and is secured to the soffitt 2 bounding the cavity and sealed to the structure 1 in such a way as to form a substantially fluid-tight enclosure. A pipe 5 passes through and effects a substantially fluid-tight seal in a hole in the rigid sheet 4 so that the open end of the pipe in the cavity is at or close to the highest point in the cavity. A second pipe 7 passes through and effects a substantially fluid-tight seal in a second hole in the rigid sheet 4 at or close to the lowest point in the cavity 3, the open end of the pipe within the cavity being covered by a mesh 8.

A course aggregate 6 is blown by air under pressure into the cavity 3 through the pipe 5 until the cavity is substantially filled with the aggregate, the weight of the aggregate being supported by the rigid sheet 4. The mesh 8 at the open end of the pipe 7 prevents aggregate from entering this pipe. Air and any other fluid within the cavity 3 is then evacuated through the pipe 5. After substantially all air and other fluid has been evacuated from the cavity 3, a cement grout (not shown) is drawn into the cavity to fill the interstices between the aggregate 6, and the cement grout is permitted to set and bond firmly to the surface bounding the cavity and the surfaces of the aggregate. After the cement grout has set, the rigid sheet 4 is removed.

The filled cavity 3 has a strength substantially matching that of the structure 1 itself.

As will be seen on referring to Figure 2, an artificial structure 11 has in a surface 12 of a vertical wall of the structure a cavity 13. In order to fill the cavity 13, a rigid sheet 14 of plywood is applied over the cavity and secured to the surface 12 of the structure 11 bounding the cavity and is sealed to the structure in such a way as to form a substantiallly fluid-tight enclosure. A pipe 15 passes through and effects a substantially fluid-tight seal in a hole in the rigid sheet 14 at a position at or close to the highest point in the cavity and a second pipe 17 passes through and effects a substantially fluid-tight seal in a second hole in the rigid sheet at a position at or close to the lowest point in the cavity. The open end of the second pipe 17 is covered by a mesh 18.A fine aggregate 16 is blown by air under pressure into the cavity 13 through the pipe 15 until the cavity is substantially filled with the fine aggregate, the weight of the fine aggregate at least in part being supported by the rigid sheet 14 and the mesh 18 preventing aggregate from entering the pipe 17. All air and any other fluid is then evacuated from the cavity 13 through the pipe 15. A hardenable mixture (not shown) of cold setting synthetic resin in a liquid or semi-liquid state and a filler is then allowed to be drawn into the cavity 13 through the second pipe 17 to fill the interstices between the fine aggregate 16 and the hardenable mixture is permitted to set and bond firmly to the surface bounding the cavity and the surfaces of the fine aggregate. After the hardenable mixture has set, the rigid sheet 14 is removed.

The filled cavity 13 has a strength substantially matching that of the structure 11 itself.

Claims

1. A method of filling a cavity opening into a surface of an artificial or natural structure of the kind specified, which surface is substantially horizontal and underlies the structure, is substantially vertical or is inclined at any acute angle therebetween, which method comprises applying over the cavity and securing to said surface of the structure bounding the cavity a substantially rigid shutter and sealing the shutter to the structure in such a way as to form a substantially fluid-tight enclosure; introducing into the cavity through a pipe passing through the shutter a multiplicity of separate bodies of solid material in its natural state and/or of concrete or other material in a manufactured solid state until the cavity is substantially filled with said bodies, the weight of the bodies at least in part being supported by the rigid shutter; evacuating air and any other fluid from the cavity; allowing hardenable material in a liquid or semi-liquid state to be drawn into the cavity and to fill the interstices between the separate bodies; and permitting the hardenable material to set and bond firmly to the surface bounding the cavity and the surfaces of the separate solid bodies.

2. A method as claimed in Claim 1, wherein, after the hardenable material has set, the rigid shutter is removed.

3. A method as claimed in Claim 1 or 2, wherein the rigid shutter is formed of a fluid-impermeable material.

4. A method as claimed in Claim 3, wherein the shutter is in the form of a substantially rigid sheet of plywood or other suitable fluid-impermeable material.

5. A method as claimed in Claim 1 or 2, wherein a flexible covering of fluid-impermeable material is applied over the outer surface of the shutter and is sealed to the surface of the structure bounding the cavity.

6. A method as claimed in any one of the preceding Claims, wherein the pipe through which the solid bodies are introduced into the cavity so protrudes through the shutter into the cavity that its open end in the cavity is at or close to the highest point in the cavity.

7. A method as claimed in any one of the preceding Claims1 wherein the multiplicity of solid bodies are blown through the pipe into the cavity by air under pressure.

8. A method as claimed in any one of the preceding Claims, wherein the pipe through which the solid bodies are introduced into the cavity is also used for the evacuation of air and other fluid from the cavity.

9. A method as claimed in any one of the preceding Claims, wherein the hardenable material in a liquid or semi-liquid state is drawn into the cavity through a second pipe which passes through the shutter into the cavity so that its open end in the cavity is at or near the lowest point of the cavity.

10. A method as claimed in Claim 9, wherein the open end of the second pipe within the cavity is covered by a mesh with holes of such a size that the solid bodies are restrained from entering the pipe.

11. A method as claimed in any one of the preceding Claims, wherein all air and other fluid is substantially evacuated from the cavity before the hardenable material is introduced therein.

12. A method as claimed in any one of the preceding Claims, wherein the multiplicity of separate solid bodies is in the form of an aggregate.

13. A method as claimed in any one of Claims 1 to 11, wherein the multiplicity of separate solid bodies comprises stone or granite chippings.

14. A method as claimed in Claim 12, wherein the hardenable material is a mixture of cold setting synthetic resin in a liquid or semi-liquid state and a filler.

15. A method as claimed in any one of Claims 1 to 13, wherein the hardenable material is a cement grout.

16. A method of filling a cavity opening into a surface of an artificial or natural structure of the kind specified substantially as hereinbefore described with reference to Figure 1 or Figure 2 of the accompanying drawing.

17. An artificial or natural structure of the kind specified having in a surface which is substantially horizontal and underlies the structure, is substantially vertical or is inclined at any. acute angle therebetween a cavity opening into the surface and filled by the method claimed in any one of the preceding Claims.