AU757289B2 - Foundation void former unit - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDAPD PATENT Applicant(s): ECOFLEX AUSTRALIA PTY LIMITED A.C.N. 081 641 518 Invention Title: FOUNDATION VOID FORMER UNIT es 0 060*** *0 a 0@ 0 *0 *aa a..

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a The following statement is a full description of this invention, including the best method of performing it known to us: 2 FOUNDATION VOID FORMER UNIT Field of the Invention The present invention relates to a void former unit for use in concrete foundations.

Background to the Invention Void formers are used to minimise the cost of forming concrete foundations, especially concrete slabs. The use of void formers enables less concrete to be used in forming the slab, whilst reinforcing beams can be defined between adjacent void formers to increase slab strength.

Various void formers are known in the art, including those shown in AU584769, AU585743, AU591816, AU30129/92, 15 AU74322/91, AU37039/89, US3,109,217, US3,148,444 and US4,799,348.

AU710541 discloses the use of vehicle tyres as void 'formers. The tyres are laid side-by-side to provide a base for a concrete raft slab, and are then overlaid with 20 a mesh which supports a waterproof membrane. Edge and internal beams can also be defined around the tyres, by using a shaped water-impermeable sheet material along the edge of a row of tyres. However, construction of the base must be performed in situ, and the steps of overlaying the tyres with a mesh and then a waterproof membrane, and providing sheet material to define the edge and. internal beams, is a cumbersome and time consuming exercise.

Summary of the Present Invention In a first aspect, the present invention provides a portable unit for use as a void former in a concrete foundation including a plurality of tyres located side-byside and having, at a perimeter of the plurality of tyres, a retention element extending therearound.

In a second aspect, the present invention provides a unit for use as a void former in a concrete foundation including a plurality of tyres located side-by-side and 3 having, at a perimeter of the plurality of tyres, a continuous retention element extending therearound.

Advantageously, in the first aspect, portability is provided for, so that the unit can be formed off site and then transported on site for immediate use.

Advantageously the retention element can in the first and second aspects function to retain the tyres in the unit, and also retain a fill material therein (described below).

Preferably, the retention element is one or more lengths of tyre tread or conveyor belt mining conveyor belts), typically continuous lengths.

Preferably, each tyre has an in-use upper side wall removed therefrom. This allows for easy in-filling, and for compacting if necessary, of the units with fill 15 material. The use of fill material enhances the strength and support function of the unit in use in a concrete *-*foundation, especially a monolithic raft slab. This contrasts with the arrangement of AU710541 where no such support function is provided, and the void formers can collapse if walked on.

Preferably, in use of the unit, a fill material is located within each tyre, and between each tyre and the retention element, and in any voids between the tyres in "'.the unit. Suitable fill materials include sand (such as 25 builder's sand), aggregate, crushed cobble stone, etc.

Alternatively, or in addition to these fill materials, the fill material can be tyre portions such as side walls, tread or particulate or granular forms of tyre, or conveyor belt portions including particulate and granular forms thereof. The tread or belt is typically coiled when used as a fill material.

Preferably in the unit each tyre is fixed to each adjacent tyre. It is also preferred that each tyre is fixed at at least one fixing point to the retention element. Preferably, the fixing involves screwing, bolting or pinning.

Preferably, the retention element is located at the 4 perimeter of the plurality of tyres in a manner such that, when located on ground in use, an undercut with respect to the outermost periphery of the unit is defined between the outside of the element and the ground.

Typically, used or discarded tyres, tyre treads and conveyor belts are employed. Tyres from any vehicle, including automobiles, trucks, etc can be employed.

In a third aspect, the present invention provides a concrete foundation including one or more units as defined in the first and second aspects. Preferably, the foundation is a monolithic raft slab.

Preferably, prior to forming the slab, a reinforcing mesh for the slab is located on top of the one or more units.

15 Preferably, prior to locating the reinforcing mesh, a platform is located on top of each unit. The platform can .be formed from roll-formed sheet material roofsheeting, condeck etc.). Such sheet materials have higher structural integrity and can be walked on etc.

20 Preferably, the foundation includes a plurality of units that are positioned to define a plurality of channels therebetween such that, when concrete is poured into those channels, beams are defined which project downwardly in the foundation in use.

Preferably, each beam is keyed into the undercut between the retention element and the ground.

In a fourth aspect, the present invention provides a unit for use as a void former in a concrete foundation including a peripheral wall defined by one or more lengths of tyre tread or conveyor belt.

Tyre tread and conveyor belt are very strong and provide a structurally stable and inert retaining wall for the unit, and allow for ready in-filling of the unit. They are also freely available.

Preferably, in the fourth aspect, a fill material is located within the bounds of the wall in use.

In a fifth aspect, the present invention provides a 5 method for preparing a concrete foundation on ground, including the steps of: arranging one or more units as defined in the first, second or fourth aspects on the ground; and (ii) in-filling the units with a fill material and/or covering the unit(s) with a platform.

Preferably after step (ii) concrete is poured over the prepared concrete foundation to cover the one or more units and to fill any spaces therebetween.

Preferably after step (ii) and prior to concrete pouring, a reinforcing mesh is overlaid the one or more units, which is embedded into the concrete after concrete curing.

Preferably the platform is a roll-formed sheet 15 material roof-sheeting, condeck etc.) which is cut to size and then positioned on each unit prior to *.overlaying the reinforcing mesh.

S.Preferably reinforcing is also arranged in one or more channels defined between adjacent units, which reinforcing is also embedded in the concrete after concrete curing.

Brief Description of the Drawings Notwithstanding any other forms which may fall within the scope of the present invention, preferred forms of the invention will now be described, by way of example of only, with reference to the accompanying drawings in which: Figure 1 shows a plan schematic view of a preferred void former unit in accordance with the present invention; Figure 2 shows a schematic plan view of a concrete foundation incorporating a plurality of void former units, some of which are the same as that depicted in Figure 1; Figure 3 is a sectional side view through one of the units, (and part of another unit), and taken on the line A-A in Figure 2; Figure 4 is a perspective view of a foundation at 6 an early stage of preparation; Figure 5 is a view of the foundation of Figure 4, from an opposite end thereof, at a further stage of preparation; Figure 6 is a side perspective view of the foundations of Figures 4 and 5, at a further advanced stage of preparation; Figure 7 is a plan perspective view of an alternative preferred void former unit in accordance with the present invention; Figure 8 is a perspective view of a foundation at an early stage of preparation employing the void former unit of Figure 7; and Figures 9 and 10 are similar perspective views of 15 the foundation of Figure 8 but in varyingly advanced stages of foundation preparation.

6•O o Modes for Carrying Out the Invention Referring firstly to Figure 1, a void former 10 in accordance with the present invention includes a plurality of, in this case four, tyres 12. Each tyre preferably has had an in-use upper tyre side wall removed therefrom (as better seen in Figures 3 and 6) but with an in-use lower side wall 14 remaining intact. A retention element in the form of one or more lengths of tyre tread 16 or conveyor belt 16 extends around the perimeter of the four tyres as shown, and is attached thereto via a plurality of fastening elements in the form of screws Tec Screws), bolts or pins 18. In addition, each tyre is attached to each adjacent tyre, at adjacent treads, by screws, bolts or pins Typically when conveyor belt is employed as the surrounding retention element, only one join is required.

When tyre tread is employed, typically two lengths are required to completely surround the four tyres, so two joins arise. Typically, the retention element is also continuous, in the sense of extending completely around 7 the plurality of tyres. However, discrete lengths can be employed to extend simply between the screws or bolts 18 of adjacent tyres functioning more as discrete tying elements) By fixing together adjacent tyres, and having a retention element extending therearound in the manner as described, the void former can be made portable, and thus can be fabricated off site in a factory) with the advantages that economy of scale can arise and modern in line manufacturing procedures can be employed etc.

Figure 2 depicts schematically a plurality of void formers 10 used in a concrete foundation 25. As shown particularly in Figure 3, concrete is poured so as to leave a step 26 around the perimeter thereof, upon which a 15 course of bricks etc. can be laid. The concrete is poured so as to define a monolithic slab 28 which effectively encapsulates the void formers as shown in Figures 2 and 3.

S" Concrete also flows into channels 29 defined between adjacent void formers, to define a series of beams as S 20 described below.

As shown in Figure 2, void formers can also be formed from units 30 comprising two tyres, or from units including fractions of tyres, such as a l-tyre unit 32, or a three-tyre unit 34, (including two adjacent half tyres) Referring now to Figure 3, a cross section through the void former 10 of Figure 1 when located within slab 28 is depicted. As can be seen, each tyre has a fill material 36 located therewithin, such in-filling being more readily facilitated by the removal of the tyre upper side wall in each case. The fill material is typically lightly compacted within each void former, and typical fill materials include sand (such as builder's sand or yellow sand), aggregate, granulated rock, crushed rock or cobble, blue metal, etc.

Fill material is typically also introduced into the voids 38 (Figure 1) located between tyres, and between the 8 tyres and the tread or belt 16.

Figure 3 also shows how reinforcing rods or bars (typically made of steel or other alloy) are arranged in channels 29, typically towards the base of each channel.

Outside bars 42, which are inset from the perimeter of the concrete foundation, are also provided within the slab.

The bars 40 help define and strengthen the resultant internal concrete beams 44, and the bars 42 help define and strengthen the.resultant external concrete beams 46, both of which extend down from slab 28 after the pouring and curing of concrete.

Reinforcing mesh 48 (typically formed from steel or other alloy) is arranged in an upper part of the slab 28 to reinforce and strengthen the slab once cured. As shown 15 in Figure 6, the rods 40, 42 are spaced from underlying ground by lower spacers 50, and the mesh 48 is spaced above the void formers 10 by upper spacers 52, positioned S: as shown on the void formers.

The edges of the reinforcing mesh can be finished off 20 with a reinforcing bar 54 (Figure 3) to provide structural •...integrity of the slab at the edges thereof.

As is known, tyre treads have a curvature in cross section, as depicted in Figure 3. The retention element tyre tread or belt 16 is preferably wrapped around and attached to the tyres 12 in each void former so as to maintain this curvature, again as shown in Figure 3. This in turn has the effect of defining an undercut 56 around each of the void formers, and into which concrete can flow when the slab 28 is poured. This has the effect of capturing the void formers within the concrete foundation, thus enhancing the overall structural integrity of the formation. In addition, by locating the bars 40, 42 close to this undercut region within both the internal and external beams, the strength of the beams adjacent to the undercut is enhanced.

Referring to Figures 4, 5 and 6, and initially to Figure 4, when constructing a concrete foundation, more 9 particularly a concrete slab using void formers in accordance with the present invention, a moisture barrier in the form of sheet 58 (typically a plastic sheet) is laid onto pre-prepared ground, and over and between a surrounding form work 60, defining the perimeter of the concrete foundation. Empty void formers (left hand side of Figure 4) are then positioned on the sheet 58 in a desired location and defining channels 29 therebetween.

Fill material 36 is then introduced into each void former and lightly compacted (eg with a mechanical compactor), until each of the void formers are filled (Figure Figure 5 also illustrates that differently sized void formers in differing locations can be employed. Some of i those void formers void formers 62) can simply be 15 defined by tyre tread or conveyor belt formed into a loop I and filled with fill material with no tyres being disposed therewithin) Reinforcing is now arranged in the concrete foundation, with rods 40 being positioned in each channel .20 29 (Figure 6) and spaced above the sheet by spacers Reinforcing mesh 48 is then located and spaced above the void formers 10 by upper spacers 52.

The concrete foundation is now ready to receive a concrete pour in a known manner, to define the concrete foundation 25 of Figure 2.

Referring now to Figures 7 to 10, an alternative void former 70 is depicted. Again, the void former 70 includes four tyres 72, each preferably having an in-use upper side wall removed therefrom, but with the lower side wall remaining intact.

In this embodiment, a plurality of tyre side walls 74 are stacked within each tyre of the unit. Typically the tyre side walls are stacked up to the top of each tyre, and increase the structural stability of the tyre whilst disposing of the cut tyre side walls.

Again, tyre tread or conveyor belt 76 extends continuously around the perimeter of the four tyres and is 10 attached to the tyres via a fastening element (eg. bolts, screws etc.).

As a further fill material and as a means of disposing of further tyre or conveyor belt material, coils 78 of either tyre tread or conveyor belt can be formed and positioned within each of the tyres and between tyres. One such coil only is shown in Figure 8, but multiple numbers of coil units can be positioned within and between the tyres.

Again, as for void former 10, fill material (including granulated/particulate type tread or conveyor belt) can be introduced into the centre of each tyre and between tyres, and also between tyres and the retention element. However, if no fill material is readily 15 available, the void former 70 can be filled with tyre and :belt scrap material (side walls, tread, belt off-cuts etc.) or can function without the use of a fill material.

'In this regard, referring to Figure 8, it will be seen that each unit can have a platform 80 positioned 20 thereon. Typically the platform is fastened to the unit with screws. This can be done either on-site, or off-site in a factory and the units then transported on-site. The platform is typically formed from a roll-formed sheet material a roofing material such as corrugated steel roofing). Alternatively, material such as condeck (i.e.

concrete support decking) can be employed. Even flat sheet material can be used, including masonite, low medium or high density fibre board etc. Because the void former will ultimately be embedded in a concrete slab, scraps or offcuts can also be employed as the platform, and even leftover/waste formwork timber material can be employed.

In Figure 8, it will be seen that each void former is positioned and levelled using a levelling beam 82). Reinforcing rods or bars 83 are then positioned in channels 84 between the void formers. Platforms 80 are cut, positioned and then fastened to each unit. Typically the platforms are cut to have a shape roughly 11 corresponding to that of the void former in plan. The platform can also have holes easily cut therein to accommodate any plumbing and electrical conduits 85, as shown in Figure 8.

Referring to Figure 9, once each void former has been fitted with its associated platform, reinforcing steel mesh 86 can be positioned on top of all of the void formers. The provision of the platforms 80 makes it easy for a user to walk across the void formers, and the integrity of the void former means that weight is transferred evenly from the platform to the void former and through to the underlying ground without void former collapse, displacement etc.

As shown in Figure 10, typically the mesh 86 is 15 spaced above the void formers by employing a plurality of S- spacing elements 88 (as is known). Once the reinforcing steel mesh completely covers the foundation, concrete can be poured into the foundation (typically by being pumped thereover), the concrete filling the channels between the 20 void formers, and covering the void formers by sitting on top of the platforms thereof. The concrete progressively fills up and embeds the steel mesh therein.

A number of advantages can be identified with the void formers and construction methods as defined above: The void formers are structurally superior to prior art void formers, attributable to the use of tyres, and retaining tyre tread or conveyor belt, both of which are very strong and durable, having high tensile and reasonable compressive strength.

The void formers when filled eliminate air voids found in existing void formers, including those disclosed in Australian Patent 710541, and thus the resultant concrete foundation (slab) has increased strength.

The void formers can be filled with fill excavated from the site where the concrete foundation is to 12 be laid, thus making use of that fill and not requiring it to be dumped.

The removal of tyre upper side walls also enables the fill material to be compacted in the void formers in use, thus increasing their structural integrity.

The removal of the tyre upper side wall enables a stack of tyre side walls to be located in each tyre, and tyre and belt tread can be coiled and located within and between the tyres in the void former.

Also, granulated tyre or belt material can fill each void former, disposing further of these waste products.

0 The use of a platform with each void former makes it easy for users to walk across the foundation, for positioning of reinforcing mesh, plumbing and "'.electrical conduits etc.

The use of the platform also enhances the support offered by the void formers to spacing elements associated with the reinforcing steel mesh, which further simplifies the concrete pouring procedure.

Whilst the invention has been described with reference to a number of preferred embodiments, it should be appreciated that the invention can be embodied in many other forms.

Claims (29)

1. A portable unit for use as a void former in a concrete foundation including a plurality of tyres located side-by-side and having, at a perimeter of the plurality of tyres, a retention element extending therearound.

2. A unit for use as a void former in a concrete foundation including a plurality of tyres located side-by- side and having, at a perimeter of the plurality of tyres, a continuous retention element extending therearound.

3. A unit as claimed in claim 1 or claim 2 wherein the retention element is continuous and is one or more lengths of tyre tread or conveyor belt. i

4. A unit as claimed in any one of the preceding claims 15 wherein a fill material is located within each tyre in :use.

5. A unit as claimed in claim 4 wherein the fill material is located between each tyre and the retention element, and in any voids between the tyres in the unit. 20

6. A unit as claimed in claim 4 or 5 wherein the fill material is sand, aggregate or crushed cobble stone.

7. A unit as claimed in claim 4 or 5 wherein the fill material is tyre or conveyor belt material.

8. A unit as claimed in claim 7 wherein the fill material located within each tyre includes tyre side walls and/or particulate tyre/conveyor belt material.

9. A unit as claimed in claim 7 or 8 wherein the fill material located outside each tyre in the unit includes coiled tyre tread/conveyor belt and/or particulate tyre/conveyor belt material.

A unit as claimed in any one of the preceding claims wherein each tyre in the unit is fixed to each adjacent tyre, and each tyre is fixed at at least one fixing point to the retention element.

11. A unit as claimed in claim 10 wherein the fixing involves screwing, bolting or pinning.

12. A unit as claimed in any one of the preceding claims 14 wherein the retention element is located at the perimeter of the plurality of tyres in a manner such that, when located on ground in use, an undercut with respect to the outermost periphery of the unit is defined between the outside of the element and the ground.

13. A unit for use as a void former substantially as herein described with reference to the accompanying drawings.

14. A concrete foundation including one or more units as defined in any one of the preceding claims.

A foundation as claimed in claim 14 that is a monolithic raft slab.

16. A foundation as claimed in claim 15 wherein, prior to forming the slab, a reinforcing mesh for the slab is 15 located on top of the one or more units.

17. A foundation as claimed in claim 16 wherein, prior to locating the reinforcing mesh, a platform is located on top of each unit.

18. A foundation as claimed in claim 17 wherein the 20 platform is formed from roll-formed sheet material.

19. A foundation as claimed in any one of claims 14 to 18 that includes a plurality of units positioned to define a plurality of channels therebetween such that, when concrete is poured into those channels, beams are defined which project downwardly in the foundation in use.

20. A foundation as claimed in claim 19 wherein each beam is keyed into an undercut between the retention element and the ground.

21. A unit for use as a void former in a concrete foundation including a peripheral wall defined by one or more lengths of tyre tread or conveyor belt.

22. A unit as claimed in claim 21 including a fill material located within the bounds of the wall in use.

23. A unit as claimed in claim 22 wherein the fill material is as defined in any one of claims 6 to 9.

24. A method for preparing a concrete foundation on ground, including the steps of: 15 arranging one or more units as defined in any one of claims 1 to 13 or 21 to 23; (ii) in-filling the unit(s) with a fill material and/or covering the unit(s) with a platform.

25. A method as claimed in claim 24 wherein after step (ii) concrete is poured over the prepared concrete foundation to cover the one or more units and to fill any spaces therebetween.

26. A method as claimed in claim 25 wherein after step (ii) and prior to concrete pouring, a reinforcing mesh is overlaid the one or more units, which is embedded into the concrete after concrete curing.

27. A method as claimed in claim 26 wherein the platform is a roll-formed sheet material which is cut to size and 15 then positioned on each unit prior to overlaying the reinforcing mesh.

28. A method as claimed in any one of claims 25 to 27 wherein reinforcing is arranged in one or more channels defined between adjacent units, which reinforcing is embedded in the concrete after concrete curing.

29. A method for preparing a concrete foundation substantially as herein described with reference to the accompanying drawings. Dated this 5th day of December 2001 ECOFLEX AUSTRALIA PTY LIMITED By its Patent Attorneys GRIFFITH HACK