GB2283996A

GB2283996A - Dry stone wall block

Info

Publication number: GB2283996A
Application number: GB9323682A
Authority: GB
Inventors: Colin Cameron Green
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-11-17
Filing date: 1993-11-17
Publication date: 1995-05-24
Also published as: GB9323682D0

Abstract

The interlocking concrete dry stone wall block enables a laterally and longitudinally stable wall or structure to be built without mortar, pointing or any other adhesive substance; it has tapered truncated pyramidal projections 6 which co-operate with corresponding recesses 12 in the base of a superimposed block. The projections may also be of circular or octagonal plan; blocks half the length shown may be provided. <IMAGE>

Description

DRY STONE WALL BLOCK This invention relates to building blocks for the construction of walls and screens, and to constructions comprising such blocks.

It is an object of the invention to provide a relatively lightweight block that can be economically produced and that can be laid without the use of mortar to build a wall or screen that is able to resist side loads.

According to the invention there is provided a building block, e.g. of generally rectangular form, having upper and lower faces, of which one provided with at least one tapered projection and the other with at least one similarly tapered recess, the arrangement being such that said projection and recess of a pair of corresponding, directly superimposed blocks fit closely together to restrain relative lateral movements between the two blocks.

Preferably, said one face has a plurality of similar projections, each having a plan form that is symmetrical with respect to mutually transverse axes, e.g. being in the shape of a square, octagon or circle.

On the other face, said at least one recess is preferably of elongate form, with said faces of the block being also elongate and the longitudinal axes of the two faces and said recess lying in a common plane.

The angle of taper of the or each projection and recess should be at least 500 relative to the associated face of the block, and preferably it is over 600. The particularly preferred range is 700 to 800.

The or each projection need only have a height above the associated face of the block sufficient to ensure adequate keying between superimposed blocks and will not normally need to be more than about a quarter of the distance between said two faces of the block. The recess, on the other hand, can be made deeper to limit the weight of the block and its total depth is preferably more than half the distance between said two faces. At its base, the width of a projection is preferably more than half the corresponding dimension of the face from which it projects.

An example of a block according to the invention is illustrated in the accompanying drawings, in which: Figures 1 and 2 are top and bottom plan views respectively, and Figures 3 and 4 are longitudinal and transverse cross-sections on the lines III-III and IV-IV.

The block illustrated, which is cold-pressuremoulded from a concrete mix, has rectangular main faces including top and bottom faces 2 4 in which there are provided, respectively, projections 6 and recesses 8.

The projections are uniformly spaced along the face 2 and have a truncated pyramidal form with a square plan section and side faces 10 inclined at 700 to the horizontal.

The recesses have lower side faces 12 that taper at the same angle as the projections but these continue into upper side faces 14 that taper only sufficiently to provide an adequate moulding draft. Each recess spans the length of two projections. When two similar blocks are placed one directly on top of the other, the projections and recesses fit closely together so as to ensure that the blocks cannot slide on each other, but do not hinder direct bearing engagement between the opposed main faces of the two blocks so that succeeding courses of a wall can be kept parallel.

It will be seen that the two-axis symmetry of the square projections allows a block to be superimposed at right-angles to an underlying block, e.g. at the corner of a construction, and still provide a non-slidable engagement. For complete location by a single projection the engaging recess should have a complementary form but with the locking effect supplemented by the adjacent blocks of the construction this is not necessary and the elongated form of recess makes moulding easier. It is possible to get a similar result with octagonal or circular plan-form projections, with correspondingly modified recesses, and such projections may be preferred for the freedom they allow to construct curved or obliquely angled walls.

The dimensions of the illustrated block in plan are 400mm by 100mm and the distance between top and bottom faces 100mm. The base dimension of the projections is 60mm, and they are set at a pitch of 100mm. At their opening in the bottom face each recess measures 162mm by 62mm so there is only a nominal clearance of 2mm in each direction between the interengaging projections and recesses of two directly superimposed blocks. This is sufficient to eliminate any sideways displacements between the blocks for all practical purposes, since it is not envisaged that they will be used to construct walls of a much greater height than 3m, and still ensure that the opposed top and bottom faces are in firm engagement so that the courses of the wall can be kept level despite the dry method of construction.The height of the projections is 20mm but the recesses have a depth of 70mm to limit the weight of the block.

While these dimensions relate to a preferred form of block, in particular one which is of a relatively large size but is still not too heavy to be easily handled, they can be varied and the geometrical form of the blocks can also be modified to meet particular requirements. For example, it can be useful to have a half-length block with a single recess and a pair of projections corresponding to those of the illustrated block. It can be arranged that the illustrated block is moulded with weakening notches or the like at its central transverse plane so that it can be split into two such modified blocks.

The blocks are laid dry, i.e. without the use of mortar, and because of the manner in which they interlock they are able to form a stable wall with considerable resistance to side loads. They have a particular application to the construction of screens and containing walls. The absence of mortar means that the wall cannot be assumed to be watertight, but the ability to allow the passage of water makes the blocks well suited for use as containing walls for banks of soil, and in this they also have the advantage of being better able to cope with dimensional variations from temperature changes, and especially the effects of frosts, because they are not rigidly bonded together.

Claims

1. A concrete block with projections on the top face and corresponding indentations on the bottom face.

2. The patent primarily concerns the design of the interlocking elements consisting of male projections (LUGS) on the top face and female indentations (FROGS) in the bottom face of the blocks as claimed in Claim 1.

3. The lugs and frogs in Claim 2 can in plan view be a variety of matching shapes, e.g. square or circular.

4. Top blocks or 'coping stones' will omit the lugs and have frogs only.

z. Base slabs, similar to paving slabs, will provide a 'floating foundation' and will have lugs only.

t. The number of lugs and frogs will vary according to the length of the block.