Quantification of Clay Minerals and Its Correlation with Chemical and Index Properties of Soil

Abstract

Clay-mineral composition is one of the factors that determine the physical and engineering behaviours of fine-grained soils; however, it is usually ignored in soil investigations, because the determination of clay-mineral composition necessitates using sophisticated instruments which are time-consuming and require skilled personnel. Many correlations exist for faster prediction of soil engineering properties from its index properties, but correlations for quicker determination of the amount of clay mineral in the soil are still unexplored. This study focuses on determining the amount of clay mineral present in a soil sample rapidly by correlating clay-mineral percentages with soil index and chemical properties, which aids in selecting proper construction guidelines before undertaking construction work. 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 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 the montmorillonite percentage has shown a stronger correlation with soil index properties than illite and kaolinite percentages, because of its physico-chemical behaviour.