FIRING BEHAVIOUR OF A CLAYEY CERAMIC BODY FOR RUSTIC FLOOR TILES

This work had as its objective to evaluate the firing behavior and microstructure of a typical clayey ceramic body from Campos dos Goytacazes, Brazil, used to fabricate extruded rustic floor tiles. The firing behavior of samples fired at 650, 850 and 1050 degrees C was studied by thermal analysis (DTA/TG) and their microstructural characteristics were evaluated by mercury porosimetry and X-ray diffraction. Technological properties such as water absorption, linear shrinkage and flexural strength were also evaluated. The results showed that the clayey body presents a relatively high weight loss during firing due to a significant amount of clay mineral associated with aluminum hydroxide decomposition. After firing the clayey body developed an elevated amount of porosity and low mechanical strength. Quartz was detected as the only crystalline phase originated from the unfired body. By contrast, mullite, plagioclase feldspar and hematite appeared during the firing.