Furnace bottom ash (FBA) is produced as a by-product from two power stations in Hong Kong. The objectives of the research concentrated on the engineering properties of unbound FBA and stabilised FBA. Test results demonstrated that unbound FBA failed to meet the CBR criteria of General Specifications of Hong Kong. However, a 3-9 percent cement/lime stabilised FBA possessed much better properties for bound sub-base material. A field trial was carried out in a road construction contract near the airport. The compacted FBA layer was overlaid by the lean concrete sub-base and ultimately by unreinforced concrete slab. Subsequent survey monitoring confirmed that the FBA capping layer performed satisfactorily. satisfactorily. Based on current market prices for sub-base Type 1 and FBA, it was estimated that a saving would be achieved from the use of FBA in road construction in Hong Kong. Moreover, the environmental impact arising from stockpiling and disposal of FBA could be reduced. As a result, it is recommended that the use of FBA and stabilised FBA as unbound granular or bound sub-base materials be promoted in road construction in Hong Kong, subject to the establishment of a set of guidelines for application under different circumstances. (A)
Abstract