Mineralogy, geochemistry and physico-mechanical characterization of clay mixtures from Sa’a (Center Cameroon): possibly use as construction materials

Abstract

Six lateritic clay samples and lateritic and alluvial clay mixtures were studied in order to evaluate their potential use as raw material for bricks and tiles manufacturing. Their mineralogical and geochemical compositions were determined by X-ray diffraction and X-ray spectrometry, respectively, together with some physico-mechanical characteristics. The main minerals for the raw materials are kaolinite, quartz, goethite, hematite, and muscovite. Fluxing oxides are in low proportion (≤ 1.55 wt%) and causes insufficient sintering during firing. The flexural strength (FS) values are lower than 2 MPa for lateritic clay bricks, due to the Fe2O3 content. This justifies their amendment with alluvial clays from the near Sanaga River. The lateritic and alluvial clay mixtures were done with respectively 100, 80, 60, 40, and 0 wt% of lateritic clay and fired at 900, 950, 1000, 1050, and 1100 °C. Linear shrinkage values increase with temperature and globally with alluvial clay content. Except for one sample-based product at 900 and 950 °C, water absorption values overall remain lower than 20% which is adequate for dense bricks and roofing tiles. For the mixtures, FS values globally increase with alluvial clay content except for a few samples at some temperatures. The studied clay mixtures can be used for bricks manufacture at the five tested temperatures. Some compositions with 40, 60, and 100 wt% of alluvial clays may be used for the production of roofing tiles above 1000 °C. Fluxes amendment is needed at 1050 and 1100 °C for other mixtures to increase their FS.