Foundation void former unit

Abstract

A void former unit (10) for use in a concrete foundation (25) includes a plurality of tyres (12) located side-by-side. The void former can have a retention element in the form of tyre tread or conveyor belt (16) located around the perimeter of the plurality of tyres. Typically, each tyre has an in-use upper side wall removed therefrom, thus enabling a fill material (36) to be located within each tyre, and between each tyre and the retention element, and in any voids between the tyres in the unit The improvement comprises arranging a capping element (80) on the unit and / or in-filling the unit with fill material (74,78) formed from tyre or conveyor belt material. The unit can be used in a concrete foundation by arranging one or more of the void former units on the ground and in-filling the units with the fill material and / or covering the units with the capping element prior to concrete pouring.

Description

FIELD OF THE INVENTION [0001] The present invention relates to an improved void former unit for use in concrete foundations. BACKGROUND OF THE INVENTION [0002] 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. [0003] Various void formers are known in the art, including those shown in AU584769, AU585743, AU591816, AU30129 / 92, AU74322 / 91, AU37039 / 89, U.S. Pat. No. 3,109,217, U.S. Pat. No. 3,148,444 and U.S. Pat. No. 4,799,348. [0004] 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 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 e...

AI Technical Summary

Benefits of technology

[0008] Preferably the capping element is formed from roll-formed sheet material to aid in its structural integrity and strength. In this regard, the roll-formed sheet material is typically roll-formed steel because of its abundance and relatively low cost. Optionally the steel is galvanised or coated to minimise corrosion of the capping element within a concrete slab. Typically the roll-formed sheet is also corrugated to further enhance its structural integrity and strength. The capping element can also be formed from roll-formed sheet material such as roof-sheeting, condeck etc. Such sheet materials have high structural integrity and can be walked on etc.

[0010] By in-filling with tyre or conveyor belt material the overall structural integrity of the void former can be enhanced. The in-filling with tyre or conveyor belt material (especially used tyre or conveyor belt material) is also advantageous environmentally, as off-cuts, scrap etc. of tyre and conveyor belts can be used as the fill material, so that an increased use of an otherwise difficult to dispose of waste can be made.

[0014] Preferably, each of the plurality of tyres has an in-use upper sidewall removed therefrom. This allows for easy in-filling, and for compacting if necessary, of the units with fill material. The use of fill material enhances the strength and support function of the unit in use in a concrete foundation, especially in 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.

Problems solved by technology

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.

Images