Utilization of a sandy clay in double-fired wall tile bodies

In the production of ceramic tiles, composition of body and firing conditions determine the phase transformations and in turn affect the final properties of the product Thus, selection of relevant raw materials and characterisation of their individual physico-mechanical and chemical characteristics are very important In this study, sintering behaviour of a model double-fired ceramic wall tile body, mainly consisting of a sandy clay, was investigated Further formulations were also prepared containing the sandy clay and increasing amount of calcite and were compared with a commercial formulation Raw materials were characterized using XRF and XRD In order to study the thermal properties of the developed formulations, TGA/DTG measurements were carried out The sintering behaviour was evaluated using a double-beam optical non-contact dilatometer XRD was also used to analyse the phases before and after firing Microstructural and microchemical characteristics of the fired formulations were observed using scanning electron microscopy (SEM) Finally, the physical, mechanical and colour properties of the formulations, such as water absorption, linear firing shrinkage, bulk density, breaking strength and chromatic coordinates, were measured The results showed that it was possible to develop wall tile formulations only by appropriate mixture of sandy clay and calcite and obtain suitable technological properties