Use of recycled gypsum in road foundation construction

Interest in finding alternatives to land fill for plasterboard and other waste gypsum products has increased with the escalating costs of disposal and their reclassification as non-hazardous non-inert waste. WRAP is working to divert plasterboard waste from landfill by seeking to overcome the barriers to plasterboard recycling. One area of its work is to develop markets for the materials from plasterboard recycling (recycled gypsum and reclaimed paper). This project examined the feasibility of using plasterboard gypsum in combination with a range of mineral wastes in road bases, sub-bases and stabilised sub-grades. The project investigate the use of plasterboard gypsum (PG) combined in mixtures with blast furnace slag, cement kiln dust (CKD), cement bypass dust (BPD) and power station run-of-station ash (ROSA) to form a novel blended binder with pozzolanic properties. This novel binder had potential use to stabilise soils and to produce roller-compacted concrete (RCC) for road foundation construction. The plasterboard gypsum acts as a source of sulphate in the blended binder. The blast furnace slag used in the project was basic oxygen slag (BOS).