GB2107753A

GB2107753A - Securing expanding-anchor fastenings in concrete

Info

Publication number: GB2107753A
Application number: GB08223687A
Authority: GB
Inventors: Rainer Clover
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-08-19
Filing date: 1982-08-17
Publication date: 1983-05-05

Abstract

A metal expanding-anchor fastening 12 is secured in a concrete structure by setting it in a closed nylon sleeve 10 embedded in the structure. The sleeve 10 serves to insulate the fastening 12 against electrolytic action through the concrete with other metal bodies. The sleeve 10 can be secured to shuttering by means of fixing holes 26 to have concrete cast about it in formation of the structure, the sleeve remaining embedded in the concrete after removal of the shuttering. <IMAGE>

Description

SPECIFICATION Securing expanding-anchor fastenings in concrete By the expression "an expanding-anchor fastening" is meant, where used herein, a fastening adapted to be set in a blind hole and comprising two relatively movable components, one of which is a locking component arranged to be forced into engagement with the wall around the hole by a movement relative thereto of a setting component, so to grip the wall and prevent withdrawal of the fastening from the hole.

Expanding-anchor fastenings, usually in the form of bolts, are commonly used to provide fixings in concrete and masonry; a hole is drilied in the structure, the fastening is inserted into the hole, and a nut is tighteneo down to draw the bolt fractionally out of the hole, so to secure the fastening in the hole.

It is an object of the present invention to provide an improved method of securing expanding-anchor fastenings in concrete, and in one of its aspects the invention provides a method of securing an expanding-anchor fastening in concrete comprising casting concrete about a member providing a fastening-receiving socket, allowing the concrete to set whilst leaving said member embedded in the concrete, and inserting the anchor fastening into the socket and setting it in the socket.

Advantages arise from the fact that no hole has to be drilled in the concrete; a hole of ideal depth and diameter can be provided by the socketproviding member, and dangers of striking reinforcing bars etc. during drilling, and problems of edge breakage, are eliminated.

The socket-providing member may be mounted on shuttering during casting of the concrete.

Expanding anchor fastening are usually of metal. Where metal bodies are fixed in a concrete or masonry structure, problems can arise from electrolytic action between two bodies of different metal. Such action may take place, for example, between a fastening at the surface of a concrete structure and steel reinforcement wholly embedded in the concrete. Should it occur that it is the fastening which gives itself up to the reinforcement, rather than the other way round, the fastening may over a period be seriously weakened, and may eventually fail altogether.

It Is known for metal fastenings to be set in a pool of an epoxy resin to secure them in a structure. An oversize hole is drilled in the structure, epoxy resin is introduced into the hole, and the fastening then inserted into the unset resin and held in some way until the resin has set.

By that method, a metal fastening can be secured in a way which leaves it Insulated against electrolytic action. However, such a method is clearly inappropriate in conjunction with an expanding-anchor fastening.

Accordingly, the socket-providing member employed in a method as set out in the last preceding paragraph but four may with advantage be arranged to insulate a metal expanding-anchor fastening against electrolytic action through the concrete with any other metal bodies and being itself immune to such action. The member may be in the form of a closed sleeve and may be wholly of a plastics material (e.g. nylon).

Such en electrolytically-insuiating socket providing member might of course be of value in other than castable (concrete) structures, even though it would be necessary first to form a hole in the structure, and secure the member in the hole, before a fastening could be set in it.

The invention provides in another of its aspects a method of securing a metal expanding-anchor fastening in a structure comprising providing a socket-providing member embedded in the structure, and inserting the anchor fastening into the socket and setting it in the socket, said member being arranged to insulate the fastening against electrolytic action through the structure with any other metal bodies and being itself immune to such action.

There now follows a description, to be read with reference to the accompanying drawings, of a method of securing an expanding-anchor fastening in concrete which illustrates the invention by way of example.

In the accompanying drawings: Figure 1 is an axial section through a socketproviding sleeve, an expanding-anchor fastening being indicated diagrammatically in broken line within the socket; and Figure 2 is an end view of the sleeve.

Apparatus for use in performance of the method comprises a socket-providing sleeve 10 and an expanding-anchorfastening 12.

The sleeve 10 is moulded in one piece of a nylon plastics material. It comprises a generally cylindrical tubular portion 14 providing a cylindrical socket 1 6.

A chamfer 1 8 is provided at the entry to the socket. At an inner end of the sleeve, the socket is closed by an end wall 20 which provides an annular retaining flange 22 projecting beyond the outside diameter of the tubular portion 14. At the opposite, outer, end of the sleeve, a fixing flange 24 projects radially from the tubular portion 14: two fixing holes 26 extend through the fixing flange. An integral stiffening rib 28 of diminishing height extends from the fixing flange 24 along the tubular portion 1 4 to a position a little short of the retaining flange 22.

To secure the anchor fastening 12 in concrete the following method can be employed. The sleeve 10 is secured to the inner face of conventional shuttering, making use of the holes 26 in the fixing flange 24. Concrete is then poured around the sleeve, up to the shuttering, and allowed to set. The shuttering is then removed, leaving the sleeve 10 behind, embedded in the concrete; the retaining flange 22 ensures that the sleeve cannot be pulled out of the concrete. The anchor fastening 12 is then inserted into the socket 1 6 and set in the socket.

The plastics sleeve 10 is practically inert chemically, and is imperforate and impermeable to moisture. Accordingly, the set anchor fastening 1 2 is kept entirely out of contact with the concrete, and with moisture from the concrete, and so is insulated against electrolytic action through the concrete with any other metal bodies, such as steel reinforcement. Furthermore, the fastening is protected by the sleeve against possible corrosion by chemical agents in the concrete. The sleeve, being entirely of a plastics material, it itself immune to electrolytic action.

Claims

1. A method of securing an expanding-anchor fastening in concrete comprising casting concrete about a member providing a fastening-receiving socket, allowing the concrete to set whilst leaving said member embedded in the concrete, and inserting the anchor fastening into the socket and setting it in the socket.

2. A method according to claim 1 in which the socket-providing member is mounted on shuttering during casting of the concrete.

3. A method according to either of the preceding claims in which the socket-providing member is arranged to insulate a metal expanding-anchor fastening against electrolytic action through the concrete with any other metal bodies and being itself immune to such action.

4. A method according to claim 3 in which the socket-providing member is in the form of a closed sleeve.

5. A method according to claim 4 in which said member is of a plastics material.

6. A method of securing an expanding-anchor fastening in concrete substantially as hereinbefore described with reference to the accompanying drawings.

7. Apparatus comprising an expanding-anchor fastening and a socket-providing member in which the fastening can be set in performance of a method according to any one of claims 1 to 6.

8. A method of securing a metal expandinganchor fastening in a structure comprising providing a socket-providing member embedded in the structure, and inserting the anchor fastening into the socket and setting it in the socket, said member being arranged to insulate the fastening against electrolytic action through the structure with any other metal bodies and being itself immune to such action.

9. A method according to claim 8 in which the socket-providing member is in the form of a closed sleeve.

10. A method according to claim 9 in which said member is of a plastics material.