Calcium aluminosilicate glasses as supplementary cementitious materials

The suitability of calcium aluminosilicate glass particles as a partial replacement for cement clinker has been investigated, both in terms of cement performance and for a potential reduction in CO 2 emission. The glasses studied were either from the pure CaO―SiO 2 ―Al 2 O 3 system or contained impurities present in natural raw materials, i.e. clay, limestone and sand. In the present study the optimal composition of calcium aluminosilicate glasses suitable for this purpose is investigated by considering the consumption of limestone, melting temperature, glass forming ability, grindability and pozzolanity of the glasses. Since the investigation focuses on the low CaO region of the CaO―SiO 2 ―Al 2 O 3 system, the CO 2 derived from limestone in the raw materials is significantly less than in the case of Portland cement. In addition, the glasses exhibit pozzolanic reactivity, thereby contributing to strength development and the overall cement performance.