Geo-Polymerization of Kaolin-Amended Black Cotton Soil

Geotechnical engineers encounter several challenges in infrastructure development due to the presence of black cotton soil in the field. Black cotton soil contains a higher percentage of montmorillonite and provides low bearing capacity, high shrinkage, and high compressibility. Various ground improvement techniques are adopted to enhance the strength of these soils. Chemical treatment is one of the most important and widely adopted methods for ground improvement of high plastic clays. Alkali-activation of the geomaterials leads to the formation of various compounds that provide strength due to geo-polymerization. Utilization of kaolin serves two purposes, that is, reduction in the formation of shrinkage cracks and increase in the availability of alumina content to enhance the process of geo-polymerization. There is no study available on the geopolymerization of black cotton soil, which includes the influence of the kaolin content and alkali concentration. In this work, the shear strength of the black cotton soil and kaolin-amended black cotton soil was performed using unconfined compressive strength (UCS) tests. The UCS tests were conducted on black cotton soil amended with different percentages of kaolin using different concentrations of alkali (NaOH) under controlled curing conditions. Controlled curing refers to the heating of samples at 40℃ or 60℃ for the desired duration. The study considered the 5M, 7.5M, and 10M of NaOH, and 5%, 7.5%, and 10% of kaolin for amendment of black cotton soil. The results of the study showed the use of a sustainable binder to improve the shear strength of the black cotton soil.