Geochemistry and predictability of tropical clay behaviour using different techniques

Due to complications in describing and analysing the behaviour of earth materials resulting from alteration of rocks, detailed laboratory and empirical studies of their geochemical, geological, and mechanical properties are very essential and require great attention. In this work, geochemical indices have been used as an important tool in characterising tropical clays and mechanical behaviour has been predicted using different techniques. This was achieved by using a scanning electron microscope equipped with an electron dispersive spectrometer and conducting statistical analysis on tropical clays, materials that are frequently encountered by practising engineers. The mechanical behaviour considered were inherent (in situ specific volume), compression (compression index and intercept), and strength (uniaxial compressive strength), and the indices used were physical (e.g. fines content), mineralogical (e.g. quartz), and chemical indices (e.g. silica-to-alumina ratio). Tropical clay can be characterised by relating chemical indices with both depth and in situ specific volume, and the most appropriate chemical indices are alumina-titania index (ATI), silica-titania index (STI), and silica-to-alumina ratio (SA). The in situ specific volume will be satisfactorily predicted by the coefficient of uniformity (Cu), ATI, STI, and SA. The fines content (Fc), Cu, quartz, and the SA are the most suitable predictor for the compression behaviour. The strength will be successfully predicted by Fc. Physical, mineralogical, and chemical indices can be used to predict mechanical behaviour, and they are recommended for practitioners working on these materials depending on the properties required.