Mineralogical, geochemical and geomechanical characterization of lateritic and alluvial clayey mixture products from Monatele - Ebebda, as building materials

Abstract

This work focuses on the mineralogical and chemical analysis of two alluvial clays from the Sanaga River, four lateritic clays from Monatele and Ebebda regions in southern Cameroon and, on the physicomechanical characterization of these clayey mixtures. The exploitation of XRD patterns reveals that quartz, muscovite, kaolinite corundum and rutile are the main minerals in alluvial clays, associated with goethite, hematite and ilmenite in lateritic materials. The main oxides are SiO₂, Al₂O₃ and Fe₂O₃ in lateritic clays. The low proportion of fluxing oxides (Na₂O + K₂O + CaO + MgO < 2.50 wt%) causes insufficient sintering during firing. Their particle size distribution is suitable for roofing tiles, lightweight blocks and solid bricks. Geotechnical characterization was carried out on five representative mixtures of lateritic and alluvial clay fired at five different temperatures, 900, 950, 1000, 1050 and 1100°C. The water absorption values are suitable for bricks (< 25%) at all the tested temperatures and for roofing tiles (< 20%) except at 900°C for the mixtures of one site at Monatele and at 1050°C for the mixture with 80 wt% of lateritic clay site at Ebebda. The flexural strength values are suitable for bricks (> 2.0 MPa) in all the sites except for two mixtures at Monatele, for tiles (> 6.5 MPa) in, one site at Ebebda and for the specimens with 80 and 60 wt% lateritic clays in one site at Monatele at 950 and 1050°C. The linear shrinkage values are high, causing deformations and microcracking on the produced bricks which require an addition of degreasers in order to reduce their plasticity before being used as building materials.

Keywords: Monatele-Ebebda (Centre Cameroon), lateritic and alluvial clays, mineralogy, géochemistry, geomechanical characterization