GB2150910A

GB2150910A - Handling of concrete blocks

Info

Publication number: GB2150910A
Application number: GB08427783A
Authority: GB
Inventors: T R Street; C R Smith; J P Doody
Original assignee: FAIRCLOUGH CONSTR GROUP
Current assignee: FAIRCLOUGH CONSTR GROUP
Priority date: 1983-11-24
Filing date: 1984-11-02
Publication date: 1985-07-10
Also published as: GB8331404D0; GB2150910B; GB8427783D0

Abstract

A concrete block has at least one cast-in tube having a narrower part opening on to the surface and a wider part within the block forming a shoulder to receive the transverse part of a stem of handling finger which may be inserted into the tube and fixed in place by a barrel having an eccentric bore engaging the stem. The handling finger may be used for lifting the block. The tube may be of plastic and remain in the block after use. <IMAGE>

Description

SPECIFICATION Handling of concrete blocks This invention relates to handling concrete blocks and is especially but not exclusively applicable to handling of cast concrete segments for tunnel linings.

Pre-cast concrete blocks are used in large numbers in civil engineering and may be of a weight and shape which makes lifting by vacuum or clamping equipment difficult or impossible. It is then necessary to provide the blocks with built-in devices allowing them to be lifted or moved by means of a crane or like device. The present invention is intended to provide a handling device which may easily be incorporated in a cast concrete block at any desired point, is cheap to manufacture and has a minimal effect on the strength and appearance of the block.

According to one aspect of the invention there is provided a concrete block having cast therein at least one tube for receiving a handling finger for handling the block, the tube comprising an open-ended upper part opening on to a surface of the block and a lower part of greater internal width within the block and attached to the upper part by an internal shoulder, the bottom of the lower part being provided with a closure to prevent entry of concrete into the tube during casting of the block.

The handling finger generally comprises a longitudinal stem having a transverse projection slidable into the tube from the surface of the block so that the projection is within the lower part of the tube and the stem extends through the upper part of the tube, and a barrel slidable into the upper part of the tube having a bore surrounding the stem and eccentric to the longitudinal axis of the tube so that sliding of the barrel into the upper part of the tube urges the finger into a position in which the projection is below the shoulder. When the handling finger is inserted in the tube in this way the block may be lifted, or otherwise displaced, by force applied by a crane, winch or other mover to the end of the finger extending out of the tube, the force exerted being transmitted to the block by the transverse projection abutting the shoulder within the tube.

Any number of similar tubes to receive handling fingers may be cast into the block at different points so that the block may be moved by forces applied to different points simultaneously.

After use the handling finger may be removed from the tube by withdrawing the barrel, allowing the transverse finger portion to be centred in the tube and withdrawn. The tube may be filled with mortar when it is no longer required. The open end of the tube may be closed temporarily by a removable cap to prevent accumulation of water or other unwanted material in the tube.

The tubes may be made of a plastics material so that they are cheap and disposable; they are left in the block when the block is installed on site. A washer, for example of steel may be inserted in the lower part of the tube to abut and reinforce the shoulder.

The lower part of the tube may be of circular cross-section and have a circular shoulder; afterna- tively the lower part may comprise a major segment of a circle and have a shoulder of corresponding shape.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a cross-section of a concrete block having a handling device comprising a tube cast therein, Figure 2 is an exploded cross-section of the tube of Figure 1, cast into the block, Figure 3 is a cross-section perpendicular to Figure 1 of the wider part of the tube containing a handling finger according to one embodiment, Figure 4 is a cross-section similar to Figure 3 of the wider part of the tube according to another embodiment, Figure 5 shows a method of installing the tube of Figures 1-3 in a block.

Referring to Figures 1 and 2, a cast block of concrete 1 is provided with a cast-in tube of plastics material comprising an upper narrower cylindrical part 2 and a lower wider cylindrical part 3 connected by a circular shoulder 4. The upper part has an open end 5 substantially flush with the outer surface of the concrete block and the lower part is closed by a cap 6 of plastics material.

The lower part of the tube contains a steel washer 7 having a central hole of diameter slightly greater than the inner diameter of upper part 2 and held against the shoulder by interior projections 8 on the wall of the lower part.

A steel finger comprises a longitudinal stem 9 having a transverse projection 10. The finger is dimensioned so that it may be slid through the upper part 2 from open end 5 and projection 10 arrives in the lower part 3.

A cylindrical steel barrel 11 is also slidable into the upper part 2 and has a bore 12 eccentric to the longitudinal axis of the tube of width slightly greater than the width of stem 9 so that, when the finger has been slid into the tube, the barrel may be slid from end 5 around the finger into the position shown in Figures 1 and 3. The finger is then held in the position shown with projection 10 under the shoulder and a lifting force applied to the end of the stem 9 extending above the block has the effect of lifting the block. Stem 9 extends outside the block and terminates in a ring 20 to engage a hook attached to a crane or other lifting device.

When the finger is to be removed the barrel is first withdrawn and the finger may then be removed by sliding along part 2 ofthe tube.

The bore in the barrel and the stem 9 may be of square or any other shape of cross-section. These cross-sections may be non-circular in order to avoid unwanted rotation of the stem in the bore of the barrel.

The lower part 3 may be of circular cross-section and have a circular shoulder, as shown in Figure 3, or it may have other cross-sections, such as that of a major segment shown in Figure 4.

When blocks of concrete are to be lifted or otherwise handled tubes ofthe kind described above may be provided at several points on the surface of te-blocks and the upper ends of the stems 9 may be attached to chains for use with a crane orto other moving means. The tubes are easily installed into a concrete block when the block is case in a mould and a method of doing so is shown in Figure 5 which shows part of the wall of a mould 13 having an installing device attached thereto. The device comprises a cylindrical member 14 having an outer diameter equal to the interior diameter of the part 2 of the tube and member 14 is attached to the wall 13 by a screw passing through a bore in its centre and entering a screw-threaded socket provided in the wall 13.Part 2 of the tube with cap 6 applied is then push-fitted on to the member 14 and when the concrete is poured and set removal of wall 13 together with member 14 leaves the tube in place.

Cap 16may then be applied to opening 5 to prevent wall or other unwanted material entering the tube.

The tube described above is cheap to manufacture and easy to install in cast concrete blocks.

The tube, being of plastics material, is cheap to manufacture and the steel washer in the wider part ofthetube has the effect of reinforcing the plastics material of the shoulder. Any number of the tubes may be cast into a concrete block with a minimal effect on the strength of the block and at very little cost.

The device is especially useful for use with concrete segments for tunnel linings, but it is also useful in handling other large or awkwardly shaped bodies of concrete. It may be used for lifting or for any other mode of displacement of the block.

Claims

1. A concrete block having cast therein at least one tube for receiving a handling finger for handling the block, the tube comprising an open-ended upper part opening on to a surface of the block and a lower part of greater internal width within the block and attached to the upper part by an internal shoulder, the bottom of the lower part being provided with a closure to prevent entry of concrete into the tube during casting ofthe block.

2. A block according to claim 1, in which the tube is formed of plastics material.

3. A block according to claim 1 or 2, in which the tube is provided with a removable cap for closing the open end of the upper portion.

4. A block according to any preceding claim, in which the closure comprises a cap having a peripheral flange fitting engaging the side wall of the lower part inside or outside the tube.

5. A block according to any preceding claim, provided with a washer within the lower part abutting said shoulder.

6. A block according to any preceding claim, in which the lower part is of circular cross-section and the shoulder extends around the whole periphery of the lower part.

7. A block according to any one of claims 1 to 5, in which the cross-section of the lower part forms a major segment of a circle and the shoulder extends around the curved portion of the periphery of the lower part.

8. A block according to any preceding claim, provided with a handling finger comprising a longitudinal stem having a transverse projection slidable into the tube so that the projection is within the lower part of the tube and the stem extends through the upper part of the tube, and a barrel slidable into the upper part of the tube having a bore-surrounding the stem and eccentric to the longitudinal axis of the tube so that sliding of the barrel into the upper part of the tube urges the finger into a position in which the projection is below the shoulder.

9. A concrete block provided with a tube for receiving a handling finger, substantially as hereinbefore described with reference to the accompanying drawings.

10. A method of making a concrete block according to any preceding claim, which comprises providing a wall of a mould forthe block with an inwardly extending projection dimensioned tor fit within the upper part of the tube, fitting the open end of the tube over the projection, casting concrete in the mould around the tube to form the block, and subsequently removing the wall and projection leaving the tube cast into the block.

11. A method of making a concrete block, substantially as hereinbefore described with reference to the accompanying drawings.