GB2325677A - Shuttering member for use in casting a beam - Google Patents

Abstract

A shuttering member for use in casting a beam over a substrate 9, the member including a base portion and opposite side portions 1B,1C attached thereto, the base portion including a support structure 2 arranged such that, in use, it will support the weight of the cast material 13 but is able to reduce in depth when subjected to a compressive force, such as that due to heaving movement of the substrate 9, the opposite side portions 1 B,1C being moveable between positions in which they lie adjacent to the base portion and positions in which they extend upwardly from opposite sides of the base portion to define shuttering for sides of a beam.

Description

Shuttering member for use in casting a beam The present invention relates to a shuttering member for use in the construction industry for casting a beam over a substrate. The invention also relates to a building structure including such a shuttering member and to a method of casting a beam using such a shuttering member.

Where reference is made to casting a beam "over" or "on" a substrate it should be understood that the beam may be cast in a trench, in which case the beam is cast over the floor of the trench but is contained wholly or partly within the trench.

The invention relates, more especially, to a shuttering member for use in casting a ground beam over a substrate in which movement, particularly heaving movement, is expected. A ground beam cast directly on such a substrate (for example, clay) would be at risk from cracking and uplift as a result of excessive movement in the substrate but the risk is reduced or eliminated if a yielding member or void can be provided, between the beam and the substrate, into which this movement can take place.

It is already known to provide a support structure onto which a beam can be cast, the support structure being of a kind that will yield, if required so to do, to allow the substrate to move towards the beam. An example of such a support structure is given, for example, in GB 2 206 637.

Such a support structure has proved very effective in use, but in certain applications where beams are to be cast, in certain ground conditions, it proves unduly time consuming and/or awkward and expensive to position suitable formwork immediately above the opposite side edges of the support structure so as to provide the side walls of the shuttering for the beam. A possible solution to this problem is to adopt the proposal disclosed in GB 2 196 681 and provide a shuttering member which includes not only a base portion but also side portions extending upwardly from the opposite sides of the base portion to provide the side walls of the shuttering. A member of this kind is, however, bulky and therefore difficult and expensive to transport.

It is an object of the invention to provide a shuttering member which is suitable for use in casting a beam over a substrate, which is able to tolerate movement of the substrate towards the beam and which overcomes or mitigates the disadvantages referred to above.

According to the invention there is provided a shuttering member for use in casting a beam over a substrate, the member including a base portion and opposite side portions attached thereto, the base portion including a support structure arranged such that, in use, it will support the weight of the cast material but is able to reduce in depth when subjected to a compressive force, such as that due to heaving movement of the substrate, the opposite side portions being moveable between positions in which they lie adjacent to the base portion and positions in which they extend upwardly from opposite sides of the base portion to define shuttering for sides of a beam.

A shuttering member according to the invention is able to be just as effective as the support structure of GB 2 206 637 in accommodating movement of the substrate after casting of the beam but also greatly facilitates correct forming of the side walls of the shuttering which are integral with the base portion. It also prevents contamination from the soil and grout leakage. At the same time, because the opposite side portions can be placed in a position lying adjacent to the base portion, the member can easily be transported and stored.

Preferably the opposite side portions are defined by sheet elements. Such sheet elements need take up little space when they are positioned alongside the base portion. The sheet portions are preferably positioned alongside the top of the base portion with one sheet portion overlying the other; to allow such positioning and avoid exposure or damage to the sheet portions, their heights are preferably not more than the width of the top of the base portion.

Each sheet element is preferably formed of plastics material, preferably by extrusion, and may be made of polypropylene. Each sheet element preferably comprises a pair of opposite exterior walls connected together by portions extending between the opposite walls. Such a construction can readily be obtained by extrusion.

Preferably the sheet element is relatively deformable in respect of deformation about an axis parallel to the longitudinal axis of the base portion but is relatively stiff in respect of deformation about a horizontal axis perpendicular to the longitudinal axis of the base portion. Such deformation may be in the form of resilient bending but is preferably in the form of folding along a line. Forming the sheet element by extrusion is suited to producing a sheet element with such characteristics because it is easy to provide a sheet element which is relatively deformable about an axis parallel to the direction of extrusion, but relatively stiff about an axis perpendicular thereto.

Preferably the base portion comprises a support structure and the middle part of a sheet fastened to the top of the support structure, the sheet being wider than the support structure and having side parts which define the opposite side portions of the shuttering member.

Such a construction is especially advantageous because of its simplicity and effectiveness. The shuttering member can be made from just two components fastened together.

Preferably the sheet can be secured by bonding with adhesive to the top of the support structure.

Preferably the opposite side portions each have a thickness of less than one quarter of the thickness (the depth) of the base portion. Whilst the base portion must be of significant depth to accommodate movement of the substrate relative to the cast beam, the sheet elements are advantageously relatively thin so that, when positioned alongside the base portion, the overall size of the shuttering member is not substantially increased by the presence of the side portions. The thickness of the base portion is preferably at least lOOmm but could typically be of the order of 200 to 250mm.

Preferably, the support structure is formed from an expanded plastics material, preferably expanded polystyrene.

The support structure may be substantially solid and composed of an expanded material which is able to compress. The support structure may comprise a plurality of spaced apart walls. A single set of parallel spaced walls may be provided, but there are preferably two sets of parallel walls that extend perpendicular to one another to define cells of generally cuboidal form. The cells defined by the walls are preferably open on the bottom face of the base portion. Such a cellular support structure has proved especially effective in accommodating movement of the substrate; various forms of such a support structure are described in GB 2 206 637 A, the disclosure of which is incorporated herein by reference.

The present invention further provides a building structure including a shuttering member as defined above, a substrate on which the shuttering member is located and a cast beam below which the base portion of the shuttering member is positioned.

The invention further provides a method of casting a beam over a substrate, including the steps of placing a shuttering member as defined above on the substrate, positioning the side portions such that they extend upwardly from opposite sides of the base to define shuttering for sides of a beam and casting a beam over the base portion and between the side portions of the shuttering member.

By way of example, an embodiment of the invention will now be described with reference to the accompanying drawings, of which: Fig. 1 is a schematic end sectional view illustrating the use of a shuttering member according to the invention for casting a beam; and Fig. 2 is a bottom plan view of a short length of the shuttering member when in use.

The shuttering member shown in Figs. 1 and 2 is of elongate shape and is made from two components: a first component comprises a sheet 1 of plastics material and a second component comprises a support structure 2 composed of a first set of parallel walls 3 and a second set of parallel walls 4 perpendicular to the walls 3. The plane of each wall is perpendicular to the planes of the top and bottom of the support structure; the walls 4 extend parallel to the longitudinal axis of the shuttering member and the walls 3 extend perpendicular to the longitudinal axis. The walls 3, 4 are spaced apart at regular intervals forming a cellular construction with, in the particular example illustrated, square cells. The walls 3, 4 are continuous along their length being partly cut away where they cross one another to provide an interlocking grid of walls.

The walls 3, 4 are formed from expanded polystyrene, ideally British Standard grade HD (N) V manufactured from high density bead and are bonded to the sheet 1 in any suitable manner, for example by an impact adhesive.

The sheet 1 is a twin wall polypropylene sheet formed by extrusion; the sheet 1 has opposite exterior walls joined by webs which extend perpendicularly between the opposite walls at a spacing substantially the same as the spacing of the walls of the sheet, and in the direction of extrusion; between the walls endless longitudinal cavities of small approximately square cross-section are formed. Such sheet is known per se and one example is the sheet sold under the trade mark Correx by Correx Plastics Limited. A characteristic of the sheet that is of particular advantage in this application is that it can readily be folded along a line parallel to the direction of extrusion. The sheet 1 is bonded to the support structure 2 with the direction of extrusion parallel to the longitudinal axis of the support structure and the sheet can therefore readily be folded along a line parallel to the longitudinal axis of the shuttering member.

In typical examples of the invention the support structure has a depth within the range of 10cm to 30cm and the walls 3, 4 are spaced apart by a distance in the range of from 12cm to 18cm (centre-to-centre spacing) and have a thickness in the range of from lcm to 3cm. The thickness of the sheet 1 is typically in the range of from 0.2cm to 1cam. The overall width of the shuttering member is selected to match the overall width of the beam to be cast and the length is as long as is convenient for transport and storage. Members may be placed end to end to extend their effective length and may also easily be cut to a selected length.

The sheet is formed with a middle part 1A which overlies the support structure 2 and with side parts 1B and 1C which, when the sheet is first bonded to the support structure and is flat, project on opposite sides along the length of the member. Once the sheet 1 is bonded to the support structure, the side parts 1B and 1C can be folded inwardly through about 180 to lie immediately above the middle part 1A. When a side part is lifted the part will naturally yield at the junction (marked on one side by reference numeral 8 in Fig. 1) of the bonded middle part 1A and the side part. With the side parts 1B and 1C folded inwardly as just described, the space taken up by the shuttering member is little more than that required by the support structure and the side parts are much less exposed to possible damage. The shuttering member is transported and stored in this condition.

When the shuttering member is to be used, the support structure is placed on a substrate 9 and the side parts 1B and 1C moved into a vertical position (the side part 1C is shown in such a position in Fig. 1). Some lateral support is then required for each of the side parts 1B and 1C and that may be provided by any suitable means. For example, as shown for the side part 1C in Fig. 1, a member 10 which may be a lightweight block of the kind already used in such applications (for example, the product manufactured by Vencel Resil Limited under the trade mark Claymaster), may be placed against the side parts. Spacers 11 and reinforcement 12 may also be placed on the shuttering member before casting of concrete. Thereafter concrete 13 can be cast to form a beam.

It should be appreciated that one particular application of the invention has been described and that many variations may be made. For example, whilst in the described example the support structure 2 is formed from spaced apart walls, it may instead be formed from solid, compressible, material.

Claims (18)

Claims

1. A shuttering member for use in casting a beam over a substrate, the member including a base portion and opposite side portions attached thereto, the base portion including a support structure arranged such that, in use, it will support the weight of the cast material but is able to reduce in depth when subjected to a compressive force, such as that due to heaving movement of the substrate, the opposite side portions being moveable between positions in which they lie adjacent to the base portion and positions in which they extend upwardly from opposite sides of the base portion to define shuttering for sides of a beam.

2. A shuttering member as claimed in claim 1, in which the opposite side portions are defined by sheet elements.

3. A shuttering member as claimed in claim 2, in which each sheet element is formed of plastics material.

4. A shuttering member as claimed in claim 2 or 3, in which each sheet element is formed by extrusion.

5. A shuttering member as claimed in any one of claims 2 to 4, in which each sheet element comprises a pair of opposite exterior walls connected together by portions extending between the opposite walls.

6. A shuttering member as claimed in any one of claims 2 to 5, in which the sheet element is relatively deformable in respect of deformation about an axis parallel to the longitudinal axis of the base portion but is relatively stiff in respect of deformation about a horizontal axis perpendicular to the longitudinal axis of the base portion.

7. A shuttering member as claimed in any one of claims 2 to 6, in which the base portion comprises a support structure and the middle part of a sheet fastened to the top of the support structure, the sheet being wider than the support structure and having side parts which define the opposite side portions of the shuttering member.

8. A shuttering member as claimed in claim 7, in which the sheet is secured by bonding with adhesive to the top of the support structure.

9. A shuttering member as claimed in any preceding claim, in which the opposite side portions each have a thickness of less than one quarter of the thickness of the base portion.

10. A shuttering member as claimed in any preceding claim, in which the thickness of the base portion is at least 100mm.

11. A shuttering member as claimed in any preceding claim, in which the support structure is formed from an expanded plastics material.

12. A shuttering member as claimed in claim 11, in which the expanded plastics material is expanded polystyrene.

13. A shuttering member as claimed in any preceding claim, in which the support structure comprises a plurality of spaced apart walls.

14. A shuttering member as claimed in any preceding claim, in which there are two sets of parallel walls that extend perpendicular to one another to define cells of generally cuboidal form.

15. A shuttering member as claimed in claim 14, in which the cells defined by the walls are open on the bottom face of the base portion.

16. A shuttering member substantially as herein described with reference to the accompanying drawings.

17. A building structure including a shuttering member as claimed in any preceding claim, a substrate on which the shuttering member is located and a cast beam below which the base portion of the shuttering member is positioned.

18. A method of casting a beam over a substrate, including the steps of placing a shuttering member as claimed in any preceding claim on the substrate, positioning the side portions such that they extend upwardly from opposite sides of the base to define shuttering for sides of a beam and casting a beam over the base portion and between the side portions of the shuttering member.