Characterization and potential application of gleysols and ferralsols for ceramic industry: a case study from Dimako (Eastern Cameroon)

Abstract

Gleysol and ferralsol samples were collected at Dimako (Eastern Cameroon) to investigate their use as raw materials in the ceramic industry, using petrological and physicochemical approach. Field and analytical investigations reveal that gleysols are grey-white with sandy clay textures. The organic carbon contents are low in both soil types. These soils are characterized by low cation exchange capacity (CEC) contents (3–5.40 cmol(+)/kg). The mineral assemblage of gleysols comprises quartz and kaolinite with few amounts of anatase and zircon. In ferralsols, the mineralogical composition is quartz, kaolinite, and hematite with accessory anatase, gibbsite, goethite, and zircon. The Fourier-transform infra-red (FT-IR) spectra confirm the presence of kaolinite with ordered structure. Gleysols are richer in SiO2 than ferralsols. However, gleysols are less enriched in Al2O3 than ferralsols. Fe2O3 contents are lower in gleysols (av. = 0.93 wt% at Koba and 1.69 wt% at Dimako) than in ferralsols (6.21–8.79 wt%). The abundance of quartz and kaolinite exhibits low contents in other major elements and several trace elements (including rare-earth elements (REE)) except Zr, Sr, and Ba in some samples. The normalized REE patterns relative to parent rocks (gneisses and granites) and chondrite reveal negative and positive Ce anomalies, strong negative Eu anomalies, and intense REE fractionation. Both soils result from the intense chemical weathering of gneisses and granites under tropical humid climate. Technological properties (color, grain size distribution, linear shrinkage, water absorption, and flexural strength) increase with the firing temperature, from 1000 to 1200 °C. Petrological and technological features highlight that gleysols are inorganic clays appropriate for refractory bodies and white stoneware tiles.