Shrinkage and strength behaviour of quartzitic and kaolinitic clays in wall tile compositions

Five different clays of Indian sources were characterized and its influence in wall tile compositions was evaluated. The results show that the compositions containing a higher amount of quartzitic clays possess lower shrinkage (<1.0%) in the temperature range of 1050-1150 °C. Body compositions containing higher amount of kaolinitic clays showed lowest water absorption and highest strength due to better densification. XRD studies conducted on fired tile specimens (1150 °C) show the formation of anorthite and quartz as major crystalline phases and monticellite and mullite as minor phases. SEM picture of a selected sample show the presence of uniformly distributed pores in the matrix. No cracks were seen around the quartz grain.