GB2186313A - Spacing components usable as temporary formwork for casting concrete - Google Patents

Abstract

Spacing components are described for supporting a structure during the formation thereof, for example a building structure or foundation on expandable soil. The component consists of two box parts (1, 2) and an expandable core (11, Fig. 1B) e.g. of structural honeycomb (10, Fig. 1 B) between them. The box parts may be supplied fiat but pre-creased and/or slit and the core unexpanded for erection and assembly on site. The support may be used for a base on which concrete is cast, the support being subsequently destroyed by introduction of water into it after the concrete has set, subsequent expansion of underlying soil then does not exert undue pressure on the cast structure. <IMAGE>

Description

SPECIFICATION Spacing components The present invention relates to spacing components and has as an object the provision of an improved form of spacing component for supporting a structure during the formation thereof.

With a building construction where the sub-soil may be of an expandable or shrinkable nature, structural damage may occur in the event of such changes in sub-soil volume when great pressures are generated against the structure due to the dimensional changes being restricted by such structure.

One solution is to provide a collapsible material of sufficient thickness between the expandable soil and the buliding structure or foundation such that at a pressure substantially less than that would damage the structure, the collapsible material will undergo a reduction in thickness, thus allowing expansion ofthe sub-soil and reduction/dissipation of the dangerous pressures.

Good results have been obtained by forming the layer of panelling of expanded structural honeycomb material laminated between facing panels. At least one of the panels is formed with an array of perforations to admit moisture and the honeycomb material loses its compressive strength when wetted. The array serves to admit the moisture direct through the panels into the cells.

In accordance with the present invention, there is provided a spacing component for supporting a structure during the formation thereof against a ground layer which is of expandable nature, said component comprising an expandable cellular core of the kind having cells with walls which extend through the thickness of the material and thereby form an array of open ended cells when the core is expanded, said core being formed of a material which is rigid in the dry state and loses its rigidity when wetted or reduced in thickness, a casing for the component in the form of an inner box part and an outer box part, said outer box part being dimensioned to provide a lid for the inner box part and the sides of both box parts having depths which are less than the thickness of the core but are sufficient to overlap substantially when the core is positioned within the casing, whereby the core holds the bases of the box parts in spaced apart relationship by engagement with said bases whilst leaving a substantial overlap between said sides. At least one of said box parts may be formed with apertures for the admission of water to the cellular core. The cellular core may be slotted or perforated to facilitate the migration of water within the core.

Whereas, in practice, with a panelling having perforate facing panels it has been virtually necessary to supply it to the building site in assembled form, the spacing component as provided by the invention is readily constructed at the site itself. For this purpose the core material is preferably provided in a compact form, a structural honeycomb material being preferred (its geometry is shown in Patent Specification 591,772), and is converted to the open cellular state at the site. Its horizontal sizes may be cut, on site, to fit the requirements and the residues from the cutting used as convenient.

The overlap between the cartons secures them together in the horizontal direction and the thickness of the core determines their vertical spacing. Water entering the panelling flows through the structure to soften the core and allow the casing to collapse as necessary.

When the two box parts are formed of corrugated cardboard, the flutes thereof may be so oriented that the flutes of the inner box part run substantially perpendicular to those of the outer box part. In a preferred arrangement, the apertures are elongated apertures, the box parts are formed of corrugated cardboard and the apertures are elongated in the direction of the corrugations. With a preferred arrangement, in which the box parts are formed from rectangular material, the creases extend to the edge thereof and the corner portions defined by the creases and the edges are creased to facilitate folding of the corner portions into contact with the side parts when the side parts are erected by folding along the elongated creases.

In another arrangement the box parts are formed from rectangular material, the creases join the corner portions together and, at each corner portion, one crease runs along one boundary of the corner portion and a slit runs along the outer boundary.

The box parts are readily provided in such form as to facilitate transport. Thus they may be provided in the flat state for erection at the building site. Their corner parts may be formed with cuts or creases to facilitate erection. Alternatively the box parts may be provided free from the cuts or creases for formation thereof on the site.

The following description of preferred embodiments of the spacing components, in which description reference is made to the accompanying drawings, is given in order to illustrate the invention. In the drawings: FIGS. 1A, 1 B and 1C are perspectives respectively showing the top box part, the core and the bottom box part of first spacing component according to the invention.

FIG. 1 D shows a detail of the said first spacing component, FIGS. 2 and 3 show details of parts of a second component, FIG. 4 is a diagram showing the manner in which a component according to the invention is employed, and FIGS. 5 and 6 show details of a component when assembled for use.

FIGS. 1A and 1 C show respectively the outer 1 and inner 2, of the box parts of a first spacing component, these parts being formed of water resistant cardboard which, if of corrugated construction, has the directions of the flutes indicated by double headed arrows. Their sides are formed with slots 5 near the bases. These slots conveniently run in the same direction as the flutes of the material in which they are formed. These box parts 1 and 2 are supplied flat and formed with creases 3 and 4 parallel with their edges. Those creases 3 which run in the same direction as the flutes terminate in slots 7.When the box parts are given a box-like configuration by bending them along the creases, their corner portions 8 are turned through 90" and secured in position by staples 9 to secure the box parts in a stable box-like configuration.

A preferred alternative to forming the box parts with slots 9 is to crease the corner parts diagonally as indicated at 9a in FIG. 2 and to manipulate the material at the corners to provide flaps 12 as shown in FIG. 3 for securing by staples 9'.

When the core 10, supplied in the unexpanded state to the site, is expanded to the open cellular state, indicated at 10 in FIG. 1 B, it forms a structure of which the limits correspond with the cuboid 11.

This cuboid has a thickness which is greater than the depth of the box parts.

FIG. 4 shows the assembly of the core and box parts of FIGS. 1 to 3 in a typical application. It supports a cast in situ suspended concrete floor 13 having reinforcing rods 14 above an earth layer of clay or other potentially expandable soil 15. The bases of the box parts 1 and 2 are held spaced apart expanded by the core 10, the spacing being greater than the depths of the individual box parts and the slots of each box part are covered by the sides of the other.

The position of slots 5 in the box parts 1 and 2 and their relationship to each other (see FIGS. 5 and 6) can be arranged to prevent the passage of casual water or rain into the box during construction operations. Subsequently when the floor 13 or other structural components such as piles or beams has acheived structural strength, water may be deliberately introduced to a level which ensures entry through the slots and thus weakens the core.

This ensures that the strength of the core is reduced to offer minimum resistance to forces exerted by expandable soils and hence provide a void to accommodate such soil movements.

The box parts 1 and 2 may be made of water resisting materials or treated during manufacture or use with coatings of water-proofing composition.

In most cases the spacing components of the present invention are required for supporting a building or parts thereof erected upon a loadbearing foundation. The load-bearing foundation may however be employed for applications in which no permanent load is provided, for example as a base to carry temporary structures or to render the site capable of supporting vehicles. One example of such use is to provide a rigid area between the supporting pillars of an inclined part of a bridge structure which provides an inclined approach or exit between the ground level and the elevated section of the bridge which crosses a river, a major road way or a railway.

It will be understood that various departures from embodiments specifically described herein may be made without departing from the scope of the invention.

Claims (11)

1. A spacing component for supporting a structure during the formation thereof, the component comprising an expandable cellular core of the kind having cells with walls which extend through the thickness of the material and thereby forming an array of open ended cells when the core is expanded, the core being formed of a material which is rigid in the dry state and loses its rigidity when wetted or reduced in thickness, and a casing for the core in the form of an inner box part and an outer box part, the outer box part being dimensioned to provide a lid for the inner box part, and the sides of both box parts having depths which are less than the thickness of the core but are sufficient to overlap substantially when the core is positioned within the casing, whereby the core holds the bases of the box parts in spaced apart relationship by engagement with the bases while leaving a substantial overlap between the sides.

2. A spacing component according to claim 1 wherein at least one of the box parts is formed with apertures for the admission of water to the cellular core.

3. A spacing component according to claim 1 or 2 wherein the cellular core is slotted or perforated to facilitate the migration of water inside the core.

4. A spacing component according to any one of claims 1 to 3 wherein the core material is a structural honeycomb.

5. A spacing component according to any one of claims 1 to 4 wherein the box parts are formed of cardboard.

6. A spacing component according to claim 5 wherein the cardboard is water resistant sheets of material creased and erected to provide the box parts.

7. A spacing component according to claim 5 or 6 wherein the cardboard is corrugated sheets of material creased and erected to provide the box parts.

8. A spacing component according to any one of claims 1 to 7 wherein the box parts are formed from rectangular sheets of material creased and erected to provide the box parts.

9. A spacing component according to claim 8 wherein the sheets of rectangular material are cut or slit as well as creased.

10. A spacing component substantially as hereinbefore described with reference to the accompanying drawings.

11. A kit of parts comprising a pair of sheets foldable to form box parts and an expandable core in unexpanded state, the parts being dimensioned to provide, when the sheets are formed into box parts and the core is expanded and placed between them, a spacing component according to any one of the preceding claims.