Physical and mechanical properties improvement of a porous clay ceramic

This work deals with the chemical, physical, thermal and mechanical analyses of porous clay and non-plastic clays mixtures from Tunisia. Five mixtures which are M1 (70 mass% clay + 30 mass% waste brick), M2 (70 mass% clay + 15 mass% waste brick + 15 mass% sand), M3 (70 mass% clay + 30 mass% sand), M4 (70 mass% clay + 30 mass% chamotte) and M5 (70 mass% clay + 15 mass% chamotte + 15 mass% sand) were sintered between 900 and 1100 °C and were evaluated for their possible ceramic applications. Thermal analysis (DTA/TG), dilatometry, X-ray diffraction (XRD), scanning electron microscopy (SEM) and physical-mechanical analyses (tensile strength, water absorption and bulk density) were used to assess the thermal behavior, phase evolution and microstructure of the fired mixtures. The formations of both the anorthite phase and the vitreous phase have improved the required ceramic product performance. M1 has the highest values of tensile strength and bulk density at 1100 °C. According to the European Norm EN 14411, all the mixtures belong to the BIII group which are suitable for the production of earthenware and unglazed stoneware.