Use of clay in the manufacture of lightweight aggregate

Clay is used as a raw material for the production of lightweight aggregates because it is readily processed into suitable granules and forms low-density but high strength aggregate particles when sintered at relatively low temperatures. The use of waste clay generated by major infrastructure development projects to make lightweight aggregate has a positive environmental impact and contributes towards a more circular economy. This paper reviews the manufacturing process used to produce lightweight aggregates from clay and the influence of processing conditions on properties. It also reviews secondary materials that have been incorporated into clays to produce lightweight aggregates. Additional research is required to improve understanding of the effects of composition and production parameters on the pore structure, density, water adsorption and strength of clay derived lightweight aggregates.