Revisiting demolition waste management

Waste arising from the construction, repair, maintenance and demolition of buildings, structures and roadways is generally termed as Construction and Demolition waste or CDW. A large quantity of demolition waste is produced every year and this creates a major environmental concern. On the other hand an even larger quantity of concrete is produced every year and this consumes a lot of natural aggregates. This creates a concern to preserve natural aggregates. Recycling concrete and masonry waste into recycled concrete aggregate (RCA) and using it in new construction is a natural way of addressing both these concerns. But existing practice uses RCA only as the base material which is low in value. This is due to the fact that the quality of the concrete debris, the raw material for the current recycling process, is of varied quality. This is a Technology Management problem that needs development of better technology. After reviewing the literature this paper proposes a process where the concrete debris is analysed using spot samples and the raw material is categorised before the production process begins. The categorisation is confirmed with continuous sampling during production. This evidence based categorisation of the RCA produced, permits the RCA to be used for structural and non-structural concrete with confidence. The paper proposes the findings from the literature and the proposed process in detail.