Enhancing the Geotechnical Properties of Expansive Soils through Coconut Shell Ash Treatment: An Experimental Investigation

Expansive Soils (ES) present a significant challenge to civil engineering projects worldwide due to their propensity to undergo volumetric changes in response to fluctuations in the moisture content. This study examined the potential of Coconut Shell Ash (CSA) as a soil stabilizer to mitigate the adverse effects of ES. The objective was to conduct a systematic evaluation of the impact of CSA on a range of soil properties, including the plasticity index, compressive strength, shear strength, swelling potential, and compaction characteristics, across a diverse array of soil types. This study adopted a comprehensive methodology, which involved the laboratory testing of soil samples with varying proportions of CSA. The tests included the determination of the Atterberg limits, the evaluation of the compaction properties, unconfined compression tests, and swelling tests. The findings revealed significant variations in the soil properties in response to the CSA content. The plasticity index responses exhibited a range of subtle changes, with a downward trend at lower CSA concentrations and more complex behaviors at higher concentrations. The compaction characteristics exhibited alterations in the optimum moisture content and maximum dry unit weight, indicating changes in soil density and stability. Similarly, the compressive and shear strength properties exhibited fluctuations with varying CSA content, underscoring the necessity for a comprehensive assessment of soil stability under CSA-treated conditions. Additionally, swelling tests demonstrated the potential of CSA to mitigate soil expansiveness, with lower swelling percentages observed in treated soils. This study highlights the importance of considering the soil type, CSA content, and engineering requirements to optimize the effectiveness of CSA in soil stabilization applications.