Development of ceramic tiles from common clay and blast furnace slag

With an objective of making ceramic tile, granulated blast furnace slag (GBFS) and common clay were mixed whereby calcia:silica ratio (w/w) varied from 0.04 to 0.86. Calcia and silica combined to form wollastonite as the major phase in the sintered microstructure. Excess silica combined with magnesia, iron oxide and alumina to form enstatite, fyalite and alumino silicates respectively during sintering. Optimum compositions were found to be where calcia-silica ratio were in the range of 0.1–0.3 where mechanical strength and water absorption of the fired specimen were in the range of 28–38 MPa and 2.5–0.1%, respectively. Physical properties of the sintered specimen are explained on the basis of XRD and SEM analysis. Formation of wollastonite in the sintered compacts with finer grain size was found to be an important parameter for increase in strength.