Utilization of Agricultural Wastes in Enhancing Strength and Reducing Shrink-Swell Potential of Expansive Soils

This study determined the effects on the strength performance of expansive soil with rice husk ash (RHA) combined with coconut shell ash (CSA) as admixtures calcined at varying durations.The expansive soil sample was sourced from the proposed sanitary landfill site excavated at a depth of almost 2 meters.The expansive soil was mixed with 20% RHA as the primary stabilizing agent to control the shrink-swell potential and a varying amount of CSA as the binder to improve the strength of the expansive soil.The samples were mixed with either tap water or seawater to examine their effects on the soil's shrink-swell potential and strength.Laboratory tests like Atterberg limits, compaction by standard Proctor, unconfined compressive strength (UCS), and California Bearing Ratio (CBR) were conducted to determine the improvement in the soil properties.All specimens showed improvement in UCS by increasing more than 345 kPa.The sample with 10% CSA and 20% RHA calcined at 10 hours showed the most significant improvement.The specimen soaked with tap water yielded higher CBR values than the specimen soaked with seawater, with 10-hour calcination.Based on the load-bearing capacity, the maximum strength improvement of expansive soil was achieved when mixed with 10% CSA and 20% RHA at 10 hours of calcination soaked in tap water.