Studies on the Compressibility Compaction and Shear Strength Parameters of Natural Clays with Varying Mineral Composition

Abstract

Clay mineral composition is one of the factors that determines the physical and engineering behaviour of fine-grained soils, however, it is usually ignored in soil investigations. The determination of clay mineral composition necessitates using sophisticated instruments which are time-consuming and require skilled persons. Many correlations exist for faster prediction of soil engineering properties from its index properties, but correlations for quicker determination of amount of clay mineral in the soil are still unexplored. This study focuses on determining the amount of clay mineral present in the soil sample rapidly by correlating clay mineral percentages with soil index and chemical properties. Clay soil samples collected from 20 different locations in Tamil Nadu state in India were subjected to chemical tests, like cation exchange capacity (CEC), specific surface area (SSA), and total potassium (TP), to quantify stable clay minerals such as kaolinite, illite, and montmorillonite. Correlations were developed for kaolinite, illite, and montmorillonite percentages in terms of chemical (CEC, SSA, and TP) and index properties. It was observed that montmorillonite percentage has shown a stronger correlation with soil index properties than illite and kaolinite percentage, because of its physicochemical behaviour. newlineThe major mineral constituents of clay soils - kaolinite, illite, and montmorillonite are stable forms of minerals and have a greater impact on the engineering behaviour of clays as compared to other types of clay minerals. Compressibility is the important property of the clay soil, needed for settlement analysis. newline