Preparation and application of calcium sulfoal uminate expansive additives using industrial by-products and wastes

Calcium sulfoaluminate (CSA) was prepared using natural limestone (CaCO3) and industrial by-products and wastes, such as Al(OH)(3) and CaSO4 (.) 2H(2)O. The mixture of raw materials was fired at 20, 400, 600, and 800degreesC for 1 h and cooled rapidly in air. The properties of the cement replaced with 10 wt% C(4)A(3)(S) over bar as expansive additives were investigated by measuring the morphology of its hydrated products, compressive strength, setting time, and expansion under wet curing conditions. The setting time of the cement pastes added clinkers was shorter than that of ordinary portland cement by about I h. The compressive strength was higher than that of ordinary portland cement by about 0similar to10%. The hydration products were mainly ettringite and Ca(OH)(2). The expansion due to the formation of ettringite during hydration decreased the drying shrinkage of hardened cement rather than that of the ordinary portland cement.