Ceramic formulations prepared with industrial wastes and natural sub-products

This work describes the studies carried out with various industrial wastes and natural sub-products based on the SiO2–Al2O3–CaO system, aimed at producing ceramic products of industrial interest. The physical and chemical characterization of the waste materials is reported and their thermal behaviour is described. Several mixtures were prepared and fired at different temperatures. Compositional evolution was assessed by X-ray diffraction and fluorescence and the sintered samples were characterised in terms of density and mechanical strength. For comparison, similar compositions based on high purity grade commercial reagents were also investigated. The presence of impurities in the former waste materials induces changes on functional properties (e.g. refractoriness). However, those variations are easily predicted and can be accounted for.