Energy-saving cements obtained from chemical gypsum and other industrial wastes

The main sources, properties and uses of chemical gypsum are reviewed and the possibility of its utilization for the manufacturing process of calcium sulphoaluminate cements is explored. In this process other industrial wastes, as sources of reactive silica and alumina, can be employed. Phosphogypsum, blast-furnace slag and fly ash were the main by-products investigated. The principal properties of calcium sulphoaluminate cements, such as synthesis, hydration and strength, were discussed. Some durability problems and suggested solutions were particularly emphasized.