Thermal behavior of ceramic wall tile pastes bearing solid wastes

Abstract

This work focuses on the thermal behavior of ceramic wall tile pastes containing solid wastes such as flat glass waste and sugarcane bagasse ash waste in partial replacement of natural raw materials. Thermal and miner- alogical transformations occurring during firing were characterized by differential thermal analysis, thermo- gravimetry analysis (TG), X-ray diffraction (XRD), and scanning electron microscopy coupled with energy-dis- persive spectroscopy. On heating four endothermic events within the 48.4-63.1, 271.0-279.1, 555.9-560.2, and 856.1-863.1 C, temperature ranges were observed. The endothermic valleys could be mainly attributed to the release of physically adsorbed water, dehydration of hydroxides (gibbsite and goethite), dehydroxylation of kaolinite, and decomposition of carbonates (calcite and dolomite), respectively. All tile pastes presented an exothermic peak within the 950.0-952.1 C temperature range associated with the crystallization of new mineral phases such as anorthite, gehlenite, mullite, and diopside. However, the tile paste with addition of sugarcane bagasse ash waste also presented an exothermic peak around 581.4 C associated with the decomposition of organic compounds. TG results indicate that the total mass loss of the wall tile pastes is in the 15.1-16.8 % range, and it depends on the added solid waste. It was found that the replacement of natural raw materials (kaolinic clay and quartz) with solid wastes (flat glass waste and sugarcane bagasse ash waste), in the range up to 5 mass%, influenced the thermal behavior of the ceramic wall tile pastes. The thermal analysis results agree well with the XRD, physical properties, and sintered microstructure.