Stabilization of Puducherry Inland Clay with Lime and Quarry Dust: Geotechnical Evaluation

Background/Objectives: The expansive clay soils of the Puducherry inland region exhibit high plasticity, excessive swelling, and low shear strength, making them unsuitable for direct use in construction without stabilization. Despite the proven effectiveness of lime and quarry dust as soil stabilizers, limited research exists on Puducherry inland clay, especially regarding long-term curing, durability, and the mechanistic interactions between these stabilizers and the clay. This study investigates the effect of lime and quarry dust as stabilizing agents on the geotechnical characteristics of Puducherry inland clay. Methods: Soil samples were treated separately with varying proportions of lime and quarry dust (7%, 14%, 21%, and 28% by dry weight) to assess improvements in geotechnical behaviour. Laboratory tests, including Atterberg limits, Free Swell Index (FSI), compaction characteristics, direct shear test, and Unconfined Compressive Strength (UCS) were conducted to evaluate changes in soil properties. Findings: The plasticity index of lime-stabilized clay decreased by approximately 25%, while quarry dust-stabilized clay showed a decrease of approximately 37%. The optimum moisture content of lime-stabilized clay and quarry dust-stabilized clay decreased by about 20% and 35%, respectively. The maximum dry density of lime- and quarry dust-stabilized clay increased by about 10% and 35%, respectively. Cohesion values for both lime- and quarry dust-stabilized clay were reduced by about 28%. The UCS of lime-stabilized clay showed a significant increase up to 21% additive content, beyond which the strength dropped drastically, whereas quarry dust-stabilized clay exhibited a continuous strength increase even beyond 21% addition. The FSI of lime- and quarry dust-stabilized clay decreased by about 35% and 28%, respectively. Novelty: Utilizing quarry dust for the stabilization of clay improves soil properties, making it suitable for construction. Compared to lime, quarry dust is abundantly available and is usually disposed of in landfills, contributing to environmental pollution. Stabilizing clay with quarry dust offers two key advantages: it enhances the engineering properties of clay and helps mitigate pollution by effectively utilizing a waste material. Keywords: Clay, Soil Stabilization, Cohesion, Lime, Quarry Dust, Geotechnical Properties