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.

Abstract: A retaining wall system (10) is defined which includes a plurality of tires arranged in a plurality of courses (14). The tires can be offset within the wall and can be cut in various ways to advantageously improve the strength of the wall. In addition, reinforcing (25, 30, 32) formed from tires or conveyor belts can be associated with the wall system to improve the structural stability of the wall.

Abstract: A retaining wall system (10) is defined which includes a plurality of tyres (11) arranged in a plurality of courses (14). The tyres can be offset within the wall and can be cut in various ways to advantageously improve the strength of the wall. In addition, reinforcing (25, 30, 32) formed from tyres or conveyor belts can be associated with the wall system to improve the structural stability of the wall.