GB2212188A

GB2212188A - Concrete slab with support portions on edges

Info

Publication number: GB2212188A
Application number: GB8826589A
Authority: GB
Inventors: John Edmund Maltby Lawson
Original assignee: Supreme Concrete Ltd
Current assignee: Supreme Concrete Ltd
Priority date: 1987-11-12
Filing date: 1988-11-14
Publication date: 1989-07-19
Anticipated expiration: 2008-11-14
Also published as: GB8826589D0; GB2212188B

Abstract

There is disclosed a concrete slab 4 which, as is already known, has generally tapered edges which assist in the removal of the slab, once hardened, from the slab mould. To overcome the difficulty of stacking the slabs edge-on without them falling over, the slab of the present invention has one edge formed with two spaced apart portions 3 which are substantially square to the main body of the slab. These portions can rest squarely upon elongate parallel bearers of a support pallet on which the stack is to be transported. The main portion 2 of the edge between these square portions can have the usual taper. In the case of relatively thick slabs, the square portions need not extend for the whole depth of the slab. There is also disclosed a suitable mould for making the slab. <IMAGE>

Description

IMPROVENENTS IN CONCRETE SLABS This invention relates to improvements in slabs, stones, panels or the like which are cast in concrete, cement or other hardenable material and will for convenience be hereinafter referred to collectively as concrete slabs. The invention also relates to moulds for making such slabs.

Concrete slabs are usually cast in a pan shaped mould. In the early days the moulds were made of wood, but then metal became the usual material and latterly have been provided with liners made of plastics, such as polypropylene. The advantage of this is that the liners may be provided with a relief to impart a decorative pattern to the slab, and different slabs can be cast in the same metal mould merely by changing the liner.

Once set, concrete has of course a high coefficient of friction, and if the edges of the mould were fixed (as they usually are) and square, it would be difficult or impossible to release the slab from the mould once the concrete has cured. This difficulty is solved in a manner akin to jelly moulds by forming the edges of the mould with a taper, usually of the order of between three and eight degrees depending on size and weight, so that once the slab has moved slightly from the mould there is no further substantial contact between the edges of the slab and the sides of the mould.

This tapering of the slab has been the custom for many years, but it brings with it difficulties in handling the slab for the following reason. Concrete slabs although extremely strong in compression are very weak in tension and pre brittle. In order to reduce the risk of breakage, they are therefore usually transported and stored on edge. However, since the edges are tapered, the slabs will fall over unless supported. This means that the pallets used to transport them must be of the chair type, i.e. with an upstanding side wall against which the slabs rest. If the slabs are instead banded together for transport, when the band is broken the slabs tend to fall over.

This state of affairs has been tolerated in the industry for many years and it is an object of this invention to obviate these difficulties of the prior art.

According to the invention there is provided a concrete slab as hereinbefore defined whose edges are generally tapered for ease of mould release modified in that one edge is provided with at least two spaced support portions which are substantially square to the main body of the slab. This enables the slab to be stood on a pair of registered spaced bearers which provide for a stable support. Furthermore, the main part of the edge extending between the square portions can be provided with the usual taper. The square portions therefore can be relatively unsubstantial in length and will not greatly hinder mould release, if at all. Thus the benefits of easy mould release coupled with ability to store the slabs stably on their edges are both achieved by this invention.

Another preferred feature is that the square edge portions are substantially tangential to the curve where the tapered portion of the edge merges with the upper flat surface of the slab. With this feature, the transition between tapered portion and square portion cannot be discerned from above once the slab is laid because the tapered section on the edge acts as a spacer to give constant base size.

The square portions must be of sufficient size to be able to support the slab edge-on. In the case of thin slabs the square portions will extend generally over the whole depth of the slab. On thicker slabs however the square portions need extend over only that part of the depth which is sufficient to provide a stable support, the remainder of the depth being tapered continuously with the tapered portion of the edge.

In order that the invention may be readily understood, certain embodiments thereof will now be described by way of example with reference to the accompanying drawings in which: Fig. 1 is a perspective view of a slab according to the invention; Fig. 2 is a plan view of the slab shown in Fig.

1; Fig. 3 is a sectional view of edge portions of the slab, taken on lines III-III of Fig. 2; Fig. 4 is a sectional view of an edge portion of the slab, taken on lines IV-IV of Fig.2; Fig. 5 is a perspective view of a mould adapted for casting the concrete slab shown in Figs. 1 to 4; Fig. 6 is an end elevational view of a slab mounted on its edge on a pallet; Fig. 7 is a side elevational view of the mounted slab shown in Fig. 6; Fig. 8 is a view to larger scale of a corner of a slab on its bearer; Fig. 9 is a plan view and Fig. 10 a side view of a pallet for storing and transporting the slabs; Fig. 11 is a perspective view of a bank of slabs stacked on edge on the pallet; and Fig. 12 is a perspective view of part of one edge of a further embodiment of slab.

With reference to Figs. 1 to 4, there is shown a square concrete slab having three edges 1 which are provided with a three degree taper to enable the slab to be released from a mould 8 as illustrated in Fig.

5. The fourth edge has a central portion 2 which is similarly provided with a three degree taper, but at each end there is a portion 3 which is substantially square to the main body of the slab.

The mould 8 comprises a pan which has a base 9 and generally outwardly inclined peripheral walls 10 which form the tapered edges of the slab 4. One of these walls has two spaced portions 11 which are substantially square to the plane of the base 9 for forming the support portions 3 of the slab.

The advantage of the squared i.e. non-tapered portions 3 will become clear on referring to Figs. 6 and 7 where the slab 4 is shown edge supported by horizontal bearers 5 which with three cross members 6 make up a simple pallet, as shown in Figs. 9 and 10.

This can be seen in greater detail in Fig. 8 which shows the slab 4 just prior to settling on bearer 5.

Since the portion 3 is square, the slab will, unlike the prior art slabs, show no tendency to topple forwards or backwards, i.e. out of or into the sheet.

In use, the slabs will usually be banded together on the pallet and it will be seen that this makes for a very stable arrangement. The pallets can be readily manoeuvred by forklift trucks whose forks engage between the cross-members 6. Once the slabs have been transported to their place of intended use and the banding is removed, the slabs will remain standing, as shown in Fig. 11 and will unlike the prior art slabs show no tendency to collapse.

It should be emphasised that the taper of central portion 2 is shown in Fig. 1 substantially exaggerated for the sake of clarity; in use it will normally be of the order of three to eight degrees. Furthermore when viewed from above, the leading corner edge 7 is continuous and no discontinuity will be perceived where tapered portion 2 joins square portion 3. This is achieved by making the tapered portion and squared portion both substantially tangential to the always present corner radius. When laid, the tapered portion 2 will act as a spacer and will uniformally spacedly cooperate either with a similar tapered portion 2 of another slab or indeed the regular tapered edge 1.

In the modified embodiment shown in Fig. 12 the square portions 3 do not extend over the whole depth of the slab, as in Fig. 1, but only for about three quarters of the depth. In a thick slab this is sufficient to provide a stable support. The remainder 8 of the depth is tapered continuously with the main tapered portion 2, which again will act as a spacer when the slab is laid.

Claims

CLAIMS:

1. A concrete slab, as hereinbefore defined, whose edges are generally tapered in the same sense with respect to the opposite slab faces for ease of mould release modified in that one tapered edge is provided with at least two spaced support portions which are substantially square to the main body of the slab.

2. A concrete slab according to claim 1 wherein the main portion of said one edge extending between the support portions is tapered.

3. A concrete slab according to claim 2 wherein the support portions are substantially tangential to the curve where the tapered main portion of the edge merges with the upper flat surface of the slab.

4. A concrete slab according to any preceding claim wherein said support portions extend over the whole depth of the slab.

5. A concrete slab according to claim 2 wherein said support portions extend over only a lower part of the depth of the slab, the remainder of the depth being tapered continuously with the tapered portion of said one edge.

CLAIMS: 1. A concrete slab, as hereinbefore defined, whose edges are generally tapered for ease of mould release modified in that one edge is provided with at least two spaced support portions which are substantially square to the main body of the slab.

3. A concrete slab according to claim 2 wherein the support portions are substantially -tangential to the curve where the tapered main portion of the edge merges with the upper flat surface of the slab.

6. A mould for making a concrete slab according to any preceding claim, the mould comprising a pan having a base and generally outwardly inclined peripheral walls which form said generally tapered edges of the slab, one of said peripheral walls having two spaced portions which are substantially square to the plane of the base for forming said support portions of said one edge of the slab.

7. A concrete slab substantially as hereinbefore described with reference to figures 1 to 4 of the accompanying drawings.

8. A concrete slab-according to claim 7 as modified by figure 12 of the accompanying drawings.

9. A mould for making a concrete slab, substantially as hereinbefore described with reference to figure 5 of the accompanying drawings.