Comparative study of a clay before and after fired brick-making process
Mouatassim Charai, Haitham Sghiouri, Ahmed Mezrhab, Mustapha Karkri, Kamal El Hammouti
Abstract
By using X-ray diffraction, SEM/EDS spectroscopy, FT-IR spectroscopy and thermogravimetric analysis, this paper explores the structural, mineralogical and thermochemical transformations of a clay brick before and after baking process under real brick-making plant conditions. The investigated soil is a clayey soil used in brick manufacture, with a clay fraction of 59% dominated by silica. The thermal stability and the crystallinity state of the clay and its brick produced at firing temperatures of 880 °C were examined. The mineralogical transformation of kaolinite, quartz, illite and calcite were discussed and confirmed. The sintering phenomenon of clay was also observed. The thermal transport properties, including the thermal conductivity, the thermal diffusivity and the specific heat capacity were determined using a Transient Plane Source (TPS) method. A comparison of the values for the unfired clay and its associated fired brick can also be seen. It was confirmed that firing treatment has a negative effect on the thermal insulation of clay bricks due to the sintering process. Therefore, further studies are encouraged to be conducted to identify optimal firing temperatures for best pore interconnections in order to develop thermally efficient clay bricks with high porosity and good mechanical strength.