Utilisation of industrial wastes and by-products for the synthesis of special cements

Abstract Calcium sulfoaluminate, which is the main component of low energy cements, can be synthesised using pure and commercial raw materials, as well as industrial wastes and by-products. It has been found that industrial process wastes like fly ash, blastfurnace slag, phosphogypsum and bauxite fines allow the synthesis of the binder to be performed at about 1200°C with high yield and satisfactory selectivity. Besides the main mineral components calcium sulfoaluminate, dicalcium silicate and anhydrite, a number of side products (minor mineralogical phases) were also present. Furthermore, calcium sulfosilicate formed instead of dicalcium silicate in the presence of excess calcium sulfate.