GB2420569A

GB2420569A - Cellular foundation panel

Info

Publication number: GB2420569A
Application number: GB0523108A
Authority: GB
Inventors: Victor Handley; Michael Frank Ellis
Original assignee: ELLE Ltd VAN
Current assignee: ELLE Ltd VAN
Priority date: 2004-11-25
Filing date: 2005-11-14
Publication date: 2006-05-31
Also published as: GB0425914D0; GB0523108D0

Abstract

A construction unit for use in foundations or flooring has a load bearing axis and comprises material having a cellular structure 10. The cellular structure comprises channels of constant cross section and having longitudinal axes which are parallel to the load bearing axis. The cellular material 10 may comprise the majority of the unit and may form a core of the unit with upper and lower facing sheets 12 forming upper and lower surfaces of the unit. The channels may be arranged in a regular array, the channels may be tessellating hexagons. The cellular material 10 may be plastics material. The facing sheets 12 may be of plastics material and may be welded to the core. A structure may have a floor formed of one or more of the constructional units which may be arranged side by side and may be connected together by welding, adhesive or a connector. A structure may be supported by foundations 30 comprising one or more of the constructional units. These foundations may be strip foundations or raft foundations. The units may be supported by piles. Also claimed is a device for location between a pile and a construction unit, characterised by the device having a support surface supporting the construction unit and being supported by an upper surface of the pile, the support surface of the device being larger than the upper surface of the pile.

Description

I

Title - Improvements relating to Foundations and Floors This invention relates to foundations and floors, and in particular to construction units for use in the construction of foundations and floors for structures.

Methods of forming foundations and floors for structures such as buildings typically involve introducing uncured concrete into a trench within the ground, and then allowing the concrete to cure within the trench to form a concrete construction unit having an upper surface upon which the structure may be, built, or a complete concrete floor. Foundations are typically either strip foundations that provide a continuous surface beneath the load-bearing members of the structure only, or raft foundations that extend over the entire area beneath the structure. In addition, foundations may include one or more piles.

Conventional methods of forming foundations and floors suffer from numerous disadvantages including the need for the time-consuming steps of preparing uncured concrete, forming a trench within the ground that is suitable for containing the uncured concrete, and then curing the concrete within the trench. The formation of foundations and floors for relatively small structures, such as conservatories, therefore occupies a significant proportion of the time required to construct the structure.

Pre-cast concrete construction units for the formation of foundations have been developed that are manufactured off-site, and then transported to the construction site and located appropriately within the ground. Such foundations offer many advantages over conventional methods of forming foundations that involve curing concrete on-site. However, pre- cast concrete construction units are very heavy, and therefore machinery is required to locate the pre-cast construction units within the ground.

There has now been devised an improved construction unit, improved methods of forming foundations and floors, and an improved device for use in such methods, which overcome or substantially mitigate the above- mentioned and/or other disadvantages associated with the prior art.

According to a first aspect of the invention, there is provided a construction unit for use in the construction of foundations for, or the floor of, a structure, the construction unit having a load-bearing axis and comprising material having a cellular structure that defines a plurality of channels, each channel having a longitudinal axis along which the channel is of substantially constant cross- section and the longitudinal axis of each channel being orientated substantially parallel to the load-bearing axis of the construction unit.

The construction unit according to the invention is advantageous principally in that the material having a cellular structure has a reduced weight relative to conventional foundation and floor materials, such as concrete, so that the construction unit may be manipulated without the need for any machinery, thereby significantly reducing the time taken to form the foundations or floor of the structure. In addition, the air within the channels of the material acts as thermal insulation within the foundations or floor.

The material having a cellular structure preferably makes up the majority of the construction unit. Most preferably, such material forms a core of the construction unit, and upper and lower face sheets are provided that form upper and lower surfaces of the construction unit. The upper surface of the construction unit is preferably orientated generally perpendicularly to the longitudinal axes of the channels and the loadbearing axis of the construction unit, and hence is preferably orientated generally horizontally when forming part of the foundations or floor of the structure.

The channels defined by the material having a cellular structure are preferably arranged in a regular array, such as a hexagonal array. In particular, the material preferably comprises a continuous wall of substantially constant thickness that defines a regular array of channels. The channels may have any suitable cross-sectional shape, such as a circular, elliptical or polygonal cross-sectional shape.

The material having a cellular structure is preferably formed of a suitably light and strong material. Most preferably, the material is formed of a plastics materials, such as polypropylene. The plastics material may be fibre reinforced, for example with carbon-fibres or glassfibres. The face sheets of the construction unit are preferably formed from a similar material, such as glass-fibre reinforced polypropylene, such that the face sheets can be welded to a core of material having a cellular structure. The welding is preferably carried out by the application of heat, and may be carried out either during manufacture of the construction unit or on-site during construction of the foundations or floor. In addition, the construction unit may be reinforced internally with reinforcing members, and/or externally by incorporation of the construction unit into a reinforcing frame. Such reinforcements are preferably formed of a metal, such as steel.

Units comprising a core of material having a cellular structure and upper and lower face sheets are currently able to be manufactured with a thickness of up to 300mm. However, where a construction unit is required with a greater thickness, construction units may be stacked with adjacent face sheets being fixed together, preferably by welding, so as to form a single construction unit of greater thickness.

The construction units according to the invention are particularly useful in the construction of foundations for a structure. The construction unit may therefore be adapted for use in the construction of foundations for a structure.

According to a further aspect of the invention, there is provided a structure supported by foundations comprising one or more construction units as described above.

According to a further aspect of the invention, there is provided a method of forming foundations for a structure using one or more construction units as described above.

The foundations for the structure may comprise a single construction unit, or a plurality of construction units arranged adjacent to one another. Where the foundations comprise a plurality of construction units, the construction units are preferably connected together at the construction site. In this case, the construction units may be connected by welding, adhesive, or a suitable mechanical connector.

The construction unit preferably forms a part of the foundations upon which load-bearing members of the structure, such as load-bearing walls, are erected and hence supported. The construction unit preferably therefore has a flat upper surface that is orientated generally horizontally when forming part of the foundations.

The foundations formed by the one or more construction units preferably have the general form of either strip foundations or raft foundations. Where the foundations have the general form of strip foundations, the construction unit or units that form part of the foundations preferably form a continuous surface beneath the load-bearing members, such as the load-bearing walls, of the structure. Most preferably, the load-bearing members of the structure are supported by the construction unit or units. For most structures, the construction unit will therefore have an upper surface that is generally rectangular in shape.

The horizontal dimensions of the construction unit will depend upon the horizontal dimensions of the load-bearing members that it is intended to support. However, the dimensions of the construction unit will also depend upon the nature of the ground within which the foundations are formed.

Typically, construction units for use in the construction of strip foundations will have a width of between 200mm and 1000mm, and a thickness of between 100mm and 1500mm.

Where the foundations have the general form of raft foundations, the construction unit or units forming part of the foundations preferably form a continuous surface beneath the entire structure. The load-bearing members of the structure are most preferably supported by the construction unit or units, and the floor of the structure is most preferably also supported by the construction unit or units. As discussed above, the foundations for the structure may comprise a plurality of construction units that are connected together on-site.

In this case, the horizontal dimensions of the construction unit will depend upon the horizontal dimensions of the structure, and also upon the nature of the ground within which the foundations are formed. In addition, the portion of the construction unit or units upon which the load- bearing members of the structure are supported may have an increased thickness relative to the remainder of the construction unit or units. Typically, construction units for use in the construction of raft foundations will have a floor-supporting portion with a substantially constant thickness of between 100 and 500mm, and a load- bearing portion with a greater thickness of between 250mm and 1500mm.

The foundations for the structure will typically comprise one or more layers of conventional foundation materials in addition to the one or more construction units according to the invention. Conventional foundation materials include concrete, sand, gravel, etc. The construction unit or units that form part of the foundations for the structure may be supported by one or more piles. A pile typically has a load-bearing axis along which it is of constant cross-section, and is typically located within the ground with its load-bearing axis orientated substantially vertically. Each construction unit may therefore be supported by an upper surface of one or more piles.

However, since the upper surface of a pile is typically of significantly smaller area than the underside of a construction unit, it is desirable in this case to increase the area over which the force exerted by the pile on the underside of the construction unit is distributed.

Hence, according to a further aspect of the invention, there is provided a device for location between a pile and a construction unit, the device comprising a support surface for supporting the construction unit, and means for engaging an upper end of the pile such that the device is supported by an upper surface of the pile, the support surface of the device having a greater area than the upper surface of the pile.

The device according to the invention is advantageous principally because the force exerted on the underside of the construction unit by the pile is distributed over a greater area than would otherwise be the case, thereby reducing the risk of damage to the construction unit.

The device may be formed of any suitably strong material, such as steel. The device is preferably engaged with the upper end of the pile, and then the construction unit is preferably placed on, and hence supported by, the support surface.

The support surface is preferably generally flat, and may have any suitable shape. The support surface is preferably orientated generally perpendicularly to the load-bearing axes of the pile and the construction unit, when fitted. The support surface has a greater area than the upper surface of the pile, and most preferably the support surface has at least twice the area of the upper surface of the pile.

The device preferably comprises a plate, the upper surface of which forms the support surface. In addition, the device preferably includes means for fastening the construction unit to the device. Such fastening means preferably comprises a connecting member that extends upwardly from the support surface through the construction unit, and an upper member that engages the upper end of the connecting member such that the construction unit is clamped between the support surface and the upper member of the device.

Most preferably, the upper member has the form of a plate that lies alongside the upper surface of the construction unit. The upper member and the connecting member are preferably threadably engaged.

The means for engaging an upper end of the pile preferably takes the form of a socket within which the upper end of the pile is received. Where the support surface is formed by a plate, the socket is preferably formed by a skirt that extends downwardly from the underside of the plate.

The unit according to the invention may also be suitable for use in the construction of a floor of a structure. Hence, the construction unit may be adapted for use in the construction of the floor of a structure.

According to a further aspect of the invention, there is provided a structure having a floor that comprises one or more construction units as described above.

According to a further aspect of the invention, there is provided a method of forming a floor of a structure using one or more construction units as described above.

The construction unit adapted for use in the construction of the floor of a structure preferably has a similar form to the construction units adapted for use in the construction of foundations for a structure described above. However, the construction unit adapted for use in the construction of the floor of a structure will typically have a constant thickness. The floor of the structure may comprise a single construction unit, or a plurality of construction units arranged side-by-side. Where the floor comprises a plurality of construction units, the construction units are preferably connected together at the construction site. In this case, the construction units may be connected by welding, adhesive, or a suitable connector.

Preferred embodiments of the invention will now be described in greater detail, by way of illustration only, with reference to the accompanying drawings, in which Figure 1 is an exploded perspective view of a block of foundation material that forms part of a construction unit according to the invention; Figure 2 is a cross-sectional view, along line Il-Il in Figure 1, of the block of foundation material of Figure 1; Figure 3 is a schematic cross-sectional view of strip foundations comprising a first embodiment of a construction unit according to the invention supporting an external load-bearing wall of a building; Figure 4 is a cross- sectional view of a pile engaged with the construction unit of Figure 3 by means of a support device according to the invention; Figure 5 is a schematic cross-sectional view of raft foundations comprising a second embodiment of a construction unit according to the invention supporting an external load-bearing wall of a building; Figure 6 is a schematic perspective view, partly cut-away, of foundations including a construction unit according to the invention; Figure 7 is a schematic cross-sectional view of the foundations of Figure 6; Figure 8 is a perspective view of a beam that forms part of the foundations shown in Figures 6 and 7; and Figure 9 is an end view of the beam of Figure 8.

A block of material that forms part of a construction unit according to the invention is shown in Figures 1 and 2. The material comprises a core 10 having a cellular structure, and generally planar face sheets 12 bonded to the upper and lower surfaces of the core 10.

The core 10 is formed from polypropylene, and the face sheets 12 are formed from polypropylene with fibre-glass reinforcement. The material is manufactured by firstly forming the polypropylene core 10 by extruding a length of cylindrical tube, cutting the cylindrical tube into sections, and then welding the cylindrical tubes together. Flexible sheets formed of a mixture of polypropylene fibre and fibre-glass are then heated and welded to the upper and lower surfaces of the core 10 so as to form relatively rigid upper and lower face sheets 12.

The core 10 comprises a continuous wall of substantially constant thickness that defines a hexagonal array of channels. The channels each have a constant circular cross-section, and are orientated parallel to one another and parallel to the load-bearing axis of the construction unit. The channels are therefore usually orientated perpendicularly to the upper surface of the construction unit. The channels of the core 10 are sealed at each end by a face sheet 12, and therefore contain trapped air that acts as thermal insulation for the structure built upon the construction unit.

The core 10 is a cellular structure that is orthotropic in form in that it has increased strength in the direction of the longitudinal axes of the channels.

This increased strength in the direction of the longitudinal axes of the channels is caused by the self-reinforcing affect of the cellular structure. The cellular structure of the core 10 enables the core 10 to be of significantly reduced weight relative to a solid block of polypropylene having comparable strength along its load-bearing axis.

The foundation shown in Figures 1 and 2 is manufactured off-site. The foundation may be manufactured in the desired shape for the construction unit, or alternatively the material may be manufactured as a block that is cut into the desired shape for the construction unit at a later time, for example on-site.

Once the construction unit has been formed in the desired shape, it is located within a trench in the ground. A variety of different foundations may be formed using construction units comprising the material of Figures 1 and 2. For example, the construction unit may form part of strip foundations or raft foundations, and may also cooperate with one or more piles.

Figure 3 shows a first embodiment of a construction unit 30 according to the invention supporting an external load-bearing wall of a building. The construction unit 30 is formed from the material of Figures 1 and 2. The construction unit 30 forms part of foundations having the general form of strip foundations such that the construction unit 30 provides a continuous surface upon which the load-bearing walls of the building may be built.

The construction unit 30 is located at the base of a trench, and outer 31 and inner 32 leaves of a cavity wall are built up from the upper surface of the construction unit 30 with a cavity between the leaves 31,32. The cavity formed between the leaves 31,32 is charged with concrete up to ground level, and the portion of the trench adjacent to the outer leaf 31 is charged with soil up to ground level. The portion of the trench adjacent to the inner leaf 32 is charged with a lower layer of soil, and an upper layer of a base material 34, such as gravel, that extends to ground level.

A solid concrete floor 35 is then formed on the base material 34. In other embodiments, however, the floor 35 shown in Figure 3 may be formed of one or more construction units comprising the material of Figures 1 and 2, and hence having a similar form to the construction unit 30 shown in Figure 3.

The construction unit 30 may be supported by one or more piles. In this case, it is desirable to distribute the load exerted by each pile on the underside of the construction unit 30 in order to reduce the risk of damaging the construction unit 30. Figure 4 shows a support device 50 for this purpose that is engaged with a pile 40 and the construction unit 30 of Figure 3. The support device 50 is formed from steel.

The support device 50 comprises a base plate 52 that is supported at its centre, in use, by the upper surface of the pile 40, and a downwardlyextending skirt 54 that defines a socket for receiving the upper end of the pile 40 therewithin. The device 50 further comprises a rod 56 with a threaded external surface that extends perpendicularly, and hence upwardly, from the centre of the upper surface of the base plate 52, and a top plate 58 with a threaded bore at its centre that is engageable with the upper end of the threaded rod 56.

In use, the support device 50 is engaged with the pile 40 by locating the upper end of the pile 40 within the socket defined by the downwardlyextending skirt 54 such that the upper surface of the pile 40 abuts the underside of the base plate 52. An open-ended bore is formed in the construction unit 30 such that the construction unit 30 can be located on the upper surface of the base plate 52 with the threaded rod 56 extending through the bore of the construction unit 30. In this arrangement, the threaded rod 56 projects a small distance above the upper surface of the construction unit 30. The threaded bore of the top plate 58 is then engaged with the threaded rod 56 until the construction unit 30 is securely clamped between the base plate 52 and the top plate 58 of the support device 50.

Figure 5 shows a second embodiment of a construction unit 60 according to the invention supporting an external load-bearing wall of a building. The construction unit 60 is formed from the material shown in Figures 1 and 2. The construction unit 60 forms part of foundations having the general form of raft foundations such that the construction unit 60 extends across the entire area beneath the building, and provides a continuous surface upon which the building may be built.

The upper surface of the construction unit 60 has a flat and continuous central portion, upon the periphery of which an inner leaf 62 of a cavity wall is built, and a depressed outer portion upon which an outer leaf 61 is built. A floor 68 for the building is formed on the flat and continuous central portion of the upper surface of the construction unit 60, and support layers 65,66,67 are formed within the ground adjacent to the peripheral edge of the construction unit 60.

The base support layer 65 is formed from gravel, the intermediary support layer 66 is formed from ash, and the upper support layer 67 is formed from concrete paving.

The floor 68 shown in Figure 5 is formed of concrete. In other embodiments, however, the floor 68 shown in Figure 5 may be formed of one or more construction units comprising the material of Figures 1 and 2, and hence having a similar form to the construction unit 60 shown in Figure 5.

For small structures, foundations having the general form of raft foundations may be formed from a single construction unit 60. However, where a single construction unit 60 would be too large to be readily transported and handled, the foundations may be formed from two or more construction units 60. The two or more construction units 60 may be joined at their edges by welding, or alternatively piles may be formed beneath the interface between adjacent construction units 60 and the support device 50 can be used to join the adjacent construction units 60 together.

Figures 6 and 7 show foundations suitable for a relatively light structure, such as a conservatory, that comprises a floor defined by a construction unit 80 according to the invention. The construction unit 80 is formed from the material of Figures 1 and 2, and has a thickness of approximately 100mm.

The foundations shown in Figures 6 and 7 comprise a single construction unit that is supported at its periphery by four foundation beams 90 (only two of which are shown in Figure 6). One of the foundation beams 90 is shown more clearly in Figures 8 and 9. In particular, each foundation beam 90 comprises an inner box-section member 91, and an adjacent outer box-section member 92 that is of greater height and width relative to the inner box-section member 91. Furthermore, the outer box-section member 92 has an upper member 94 that projects horizontally beyond the inner wall of the outer box-section member 92 so as to define, together with an upper member 93 of the inner box-section member 91, a channel that receives a peripheral portion of the construction unit 80 during use. In particular, the upper member 93 of the inner box-section member 91 has a flat, horizontal upper surface upon which the construction unit 80 rests during use, and the upper member 94 of the outer box-section member 92 extends over a peripheral portion of the upper surface of the construction unit 80.

Each foundation beam 90 also comprises an angle-section member that forms an outer ledge 95 extending horizontally from the base of the beam 90, and an inclined support gusset 96 that is situated within the outer boxsection member 92 and supports the outer wall thereof. Each foundation beam 90 is formed of extruded aluminium that is stitch welded together, save for the angle- section member which has seam welds running along its entire length.

As shown in Figures 6 and 7, the foundation beams 90 are formed with bevelled ends that are joined together such that each beam 90 is orientated perpendicularly to its adjacent beams 90. To support the foundation beams 90, helical screw piles 100 are screwed into the ground at the corners of a suitable trench. The foundation beams 90 are then located within the trench such that the upper member 94 of the outer box-section member 92 is located at the desired level of the floor. Each pile 100 includes an end cap with a horizontal support plate that is then fastened to the base of the foundation beams 90. A peripheral portion of the construction unit 80 is then engaged with the foundation beams 90, as discussed above, so that a peripheral portion of the construction unit 80 rests upon the upper members 93 of the inner box- section members 91 of the foundation beams 90.

A bitumen-based, damp-proof membrane is applied across the entire upper surface of the construction unit 80 and the upper members 94 of the outer box- section members 92. Inner 81 and outer 82 leaves of a cavity wall are then built up on the upper member 94 of the outer box-section member 92, and the outer ledge 95, respectively. A damp-proof course 84 is included within the outer leaf 82 of the cavity wall at a similar height to the damp-proof membrane 83. Finally, internal floor and wall finishes 86,87 are applied in a conventional manner, and the cavity wall is filled with suitable insulation 87.

The foundations shown in Figures 6 and 7 comprise a floor defined by only a single construction unit 80. However, a structure according to the invention may comprise a floor defined by two or more construction units 80, which preferably have the form of strips. In addition, in order to provide additional support for the construction unit(s) 80, at least some of the foundation beams may include inner ledges that project horizontally from the inner wall of the inner box-section members 91 of the foundation beams 90. Conventional I- section beams are fastened, in use, to the upper surfaces of the inner ledges, and the construction units 80 are then arranged so that they rest upon the upper surfaces of those I-section beams.

Claims

Claims 1. A construction unit for use in the construction of foundations

for, or the floor of, a structure, the construction unit having a load-bearing axis and comprising material having a cellular structure that defines a plurality of channels, each channel having a longitudinal axis along which the channel is of substantially constant cross-section and the longitudinal axis of each channel being orientated substantially parallel to the load-bearing axis of the construction unit.
2. A construction unit as claimed in Claim 1, wherein the material having a cellular structure makes up the majority of the construction unit.
3. A construction unit as claimed in Claim 2, wherein the material having a cellular structure forms a core of the construction unit, and upper and lower face sheets are provided that form upper and lower surfaces of the construction unit.
4. A construction unit as claimed in Claim 3, wherein the upper surface of the construction unit is orientated generally perpendicularly to the longitudinal axes of the channels and the load-bearing axis of the construction unit, and hence orientated generally horizontally when forming part of the foundations or floor of the structure.
5. A construction unit as claimed in any preceding claim, wherein the channels defined by the material having a cellular structure are arranged in a regular array.
6. A construction unit as claimed in Claim 5, wherein the channels defined by the material having a cellular structure are arranged in a hexagonal array.
7. A construction unit as claimed in Claim 5 or Claim 6, wherein the material comprises a continuous wall of substantially constant thickness that defines a regular array of channels.
8. A construction unit as claimed in any preceding claim, wherein the channels have a circular, elliptical or polygonal cross-sectional shape.
9. A construction unit as claimed in any preceding claim, wherein the material having a cellular structure is formed of a plastics materials.
10. A construction unit as claimed in Claim 9, wherein the plastics material is fibre reinforced.
11. A construction unit as claimed in Claim 9 or Claim 10, wherein the face sheets of the construction unit are formed of a plastics material and are welded to a core of material having a cellular structure.
12. A construction unit as claimed in any preceding claim, wherein the construction unit is reinforced internally with reinforcing members, and/or externally by incorporation of the construction unit into a reinforcing frame.
13. A structure having a floor that comprises one or more construction units as defined by any preceding claim.
14. A structure as claimed in Claim 13, wherein the one or more construction units have a constant thickness.
15. A structure as claimed in Claim 13 or Claim 14, wherein the floor of the structure comprises a plurality of construction units arranged sideby-side.
16. A structure as claimed in Claim 15, wherein the construction units are connected together by welding, adhesive, or a suitable connector.
17. A structure supported by foundations comprising one or more construction units as defined by any one of Claims I to 12.
18. A structure as claimed in Claim 17, wherein the one or more construction units form a part of the foundations upon which load-bearing members of the structure are erected and hence supported.
19. A structure as claimed in Claim 18, wherein the one or more construction units have a flat upper surface that is orientated generally horizontally when forming part of the foundations.
20. A structure as claimed in any one of Claims 17 to 19, wherein the foundations formed by the one or more construction units have the general form of either strip foundations or raft foundations.
21. A structure as claimed in Claim 20, wherein the foundations have the general form of strip foundations, the construction unit or units that form part of the foundations forming a continuous surface beneath the load-bearing members of the structure.
22. A structure as claimed in Claim 21, wherein the one or more construction units each have a width of between 200mm and 1000mm, and a thickness of between 100mm and 1500mm.
23. A structure as claimed in Claim 20, wherein the foundations have the general form of raft foundations such that the construction unit or units form a continuous surface beneath the entire structure.
24. A structure as claimed in Claim 23, wherein the load-bearing members of the structure and the floor of the structure are supported by the construction unit or units.
25. A structure as claimed in Claim 24, wherein the portions of the construction unit or units upon which the load-bearing members of the structure are supported have an increased thickness relative to the remainder of the construction unit or units.
26. A structure as claimed in Claim 25, wherein the construction unit or units have a floor-supporting portion with a substantially constant thickness of between 100 and 500mm, and a load-bearing portion with a greater thickness ofbetween25Ommand 1500mm.
27. A structure as claimed in any one of Claims 17 to 26, wherein the foundations for the structure comprise one or more layers of conventional foundation materials in addition to the one or more construction units.
28. A structure as claimed in any one of Claims 17 to 27, wherein the construction unit or units that form part of the foundations for the structure are supported by one or more piles.
29. A structure as claimed in Claim 28, wherein each construction unit is supported by an upper surface of one or more piles.
30. A device for location between a pile and a construction unit, the device comprising a support surface for supporting the construction unit, and means for engaging an upper end of the pile such that the device is supported by an upper surface of the pile, the support surface of the device having a greater area than the upper surface of the pile.
31. A device as claimed in Claim 30, wherein the support surface is generally flat.
32. A device as claimed in Claim 30 or Claim 31, wherein the support surface is orientated generally perpendicularly to the load-bearing axes of the pile and the construction unit, when fitted.
33. A device as claimed in any one of Claims 30 to 32, wherein the support surface has at least twice the area of the upper surface of the pile.
34. A device as claimed in any one of Claims 30 to 33, wherein the device comprises a plate, the upper surface of which forms the support surface.
35. A device as claimed in any one of Claims 30 to 34, wherein the device includes means for fastening the construction unit to the device.
36. A device as claimed in Claim 35, wherein the fastening means comprises a connecting member that extends upwardly from the support surface through the construction unit, and an upper member that engages the upper end of the connecting member such that the construction unit is clamped between the support surface and the upper member of the device.
37. A device as claimed in Claim 36, wherein the upper member has the form of a plate that lies alongside the upper surface of the construction unit.
38. A device as claimed in Claim 37, wherein the upper member and the connecting member are threadably engaged.
39. A device as claimed in any one of Claims 30 to 38, wherein the means for engaging an upper end of the pile takes the form of a socket within which the upper end of the pile is received.
40. A device as claimed in Claim 39, wherein the device comprises a plate, the upper surface of which forms the support surface, and the socket is formed by a skirt that extends downwardly from the underside of the plate.
41. A method of forming a floor of a structure using one or more construction units as defined by any one of Claims I to 12.
42. A method of forming foundations for a structure using one or more construction units as defined by any one of Claims I to 12.
43. A construction unit as hereinbefore described and as illustrated by Figures Ito 4.
44. A construction unit as hereinbefore described and as illustrated by Figures 1, 2 and 5.
45. A construction unit as hereinbefore described and as illustrated by Figures 1,2,6 and 7.
46. A structure as hereinbefore described and as illustrated by Figures 1 to4.
47. A structure as hereinbefore described and as illustrated by Figures 1, 2 and 5.
48. A structure as hereinbefore described and as illustrated by Figures 1, 2, 6 and 7.