Properties of cement waste composites

Many nominally inert waste materials can be activated by alkaline substances, including Ca(OH)2 and Portland cement, to form valuable supplementary cementitious materials. Waste materials are inherently more variable in composition than well specified, manufactured materials. Nevertheless, sufficient characterisation techniques are available to permit the specification of materials such as fly ash and blast furnace slags with confidence. Applications for other processed waste materials, e.g. metakaolin, are being developed. Properly applied, these wastes can actually improve the performance of cement materials. The leach testing of products containing potentially hazardous waste materials, suited only for disposal, is described.