This study deals with the mineralogical and thermal analysis of Triassic clays in the south-Eastern Tunisia in order to use them in a faience glazed ceramic. Clays were first analysed by X-ray diffraction, chemical composition, thermal analysis and plasticity. The data collected from these techniques show that illite and kaolinite are the major clay phases. The accessory minerals detected in the powdered rock are; quartz, dolomite and hematite. This study revels that the amount of silica is relatively high and a plasticity test shows a medium value. Geotechnical characterization was carried out on the three representative mixtures of Triassic clay samples. Samples were pressed in a rectangular mould and sintered to a temperature ranging from 850 to 1150 ο C. Firing characteristics (shrinkage, water absorption, and mechanical resistance to inflection) were measured. Mechanical properties characterizations were performed by means of three-point bending tests. The optimum firing temperature of each sample has been established. The maximum bending strength of each ceramic body has been determined. Porosity-strength relations have been established. These clays could be used in the manufacture of ceramic pieces.

Keywords: Clay, Kaolinite, Ceramic, Thermal analysis, Firing.