HYDRATION PROPERTIES AND TECHNICAL BEHAVIOUR OF BLENDED BELITE CALCIUM SULFOALUMINATE CEMENTS

Belite calcium sulfoaluminate (BCSA) cements are environmentally friendly binders inasmuch as they can allow a significant reduction in CO2 emissions thanks to the saving of both fuel consumption and limestone requirement. Compared to the production of ordinary Portland cement, the manufacture of BCSA cements is characterized by further relevant sustainable features, namely: (i) lower synthesis temperature (1250°-1350°C), (ii) easier clinker grindability and (iii) larger use of industrial wastes. Moreover, their environmental sustainability can be increased by the addition of supplementary cementitious materials. The aim of this paper is to compare the hydration behaviour and the technical properties of a blast furnace slag (17.5% by mass) or a coal fly ash (17.5% by mass)- blended BCSA binder with a plain BCSA-system. All the binders, containing 2.5% by mass of slaked lime, were investigated by means of calorimetric, X-ray diffraction and differential thermal-thermogravimetric analyses, mercury intrusion porosimetry, expansion/shrinkage tests and mechanical compressive strength measurements.