Ceramic behaviour of some clay deposits from Guayas province, Ecuador: Preliminary study

This note is a preliminary study from mineralogical and chemical points of view about the possibility of using local clays from Ecuador in industrial ceramics. The chemical and mineralogical composition of clays was determined by X-ray fluorescence (XRF) and X-ray diffraction (XRD). Also, the plasticity index (PI) was measured for each sample. Test samples were prepared by pressing and firing at different temperatures. Linear contraction (LC), water absorption capacity (WAC), and bending strength were performed to characterise the fired clays. The clay deposits studied were plastic raw materials with very high contents of quartz. The raw material in traditional ceramics in Ecuador is clay with approximate levels of silica at 60%, alumina 15%, low alkalis and carbonates, and high iron levels. The sample mineralogy indicates quartz as a primary mineral, followed by plagioclases, with hematite to a lesser extent in all the samples. Kaolinite, illite, and chlorite are the main clay minerals in the raw material samples. All the studied clays seem to be easily adaptable to a correct dry pressing ceramic process. The studied clays are an excellent raw material for the formulation of low porosity ceramic stoneware.