Ceramic with potential application of ngwenfon alluvial clays (noun, west cameroon) in building construction: Mineralogy, physicochemical composition and thermal behaviour

Our aim is to characterize four types of alluvial clays from the locality of Ngwenfon situated 35 km from Foumban (West Cameroon). X-ray diffraction, thermal analysis, chemical composition, particle size distribution, organic matter content and plasticity were investigated in raw clay materials in order to determine their suitability for building material and firing bricks in particular. Ceramics properties such as linear shrinkage, water absorption, flexural strength, compressive strength, bulk density and mineral neoformations were also investigated by firing specimen bricks at a temperature range of 800 °C-1150 °C. Kaolinite, quartz, goethite, feldspar and illite represent the dominant mineral phases, in addition to minor quantities of chlorite, gibbsite, anatase and plagioclase. The main oxides are; SiO2, Al2O3, and Fe2O3. The physical parameters of the alluvial clays display a continuous and various particles size with a relatively high plastic index (12%-36%) and high organic matter contents (9%-13%). A significant densification has been observed at a temperature of 1150 °C. This was confirmed by the appearance of new mineral phases such as mullite, cristobalite and spinel, which are responsible for the increased mechanical strength and a reduction in water absorption. Most of the alluvial clays from Ngwenfon display suitable ceramic properties at sintering range from 1000 °C to 1150 °C. However, the black clays, with low ceramic properties at temperatures of 1150 °C, are inappropriate for fired brick production. These black clays are characterized by a compressive strength lower than the required value of 20 MPa for the standard reference.