Physicochemical and Mineralogical Characterization of Clay Materials in the Douala Coastal Sedimentary Sub-basin (Cameroon, Central Africa)

Abstract

This study is focused on the physicochemical and mineralogical characterization of five different clay materials of Eastern part of Douala sub-basin. It aims to know the nature and geotechnological properties of the clay raw materials in order to raise the idea of their potentialities in industrial applications. The samples were subjected to several analyses such as geotechnical tests notably the particle size distribution, the Atterberg limits, the swelling index, the chemical (cation exchange capacity, pH-H2O and pH-KCl, X-ray fluorescence) and mineralogical (X-ray diffraction) analyses. These clay materials showed high fine fractions (up to 99%) and high plasticity index (15 to 63%). The swelling index is medium (16 to 20) and the CEC moderate (30 - 40), indicating the presence of a small proportion of swelling 2:1 type clays. The clay materials are predominantly constituted by kaolinite (32 – 72%), quartz (20.2 - 50.7%) and illite (4.6 – 10%), which are characteristic of the sedimentary environment and morphoclimatic conditions of the Douala coastal sedimentary sub-basin. The predominant oxides in clay materials are SiO2 (34.05 - 51.18%) and Al2O3 (16.05 - 23.98%). Iron oxide Fe2O3 is moderate (1.55 - 11.22%) and alkali and alkaline earth oxides are weak less than 2%. The physicochemical parameters associated with mineralogical and geochemical data make them suitable for ceramic applications and also serve as backfilling materials in building constructions when improved by adding sand.