Groundnut Shell Ash as a Stabilizing Agent for Clayey Sand: A Review

Abstract

This review examines the potential of groundnut shell ash (GSA) as an eco-friendly stabilizing agent for clayey sand soils. The focus is on the chemical composition of GSA, its impact on soil properties, and its effectiveness compared to traditional stabilizers like cement and lime. GSA, a byproduct of groundnut processing, contains significant amounts of silica, alumina, and calcium oxide, which contribute to its pozzolanic activity and soil-binding properties. The addition of GSA to clayey sand reduces the liquid limit and plasticity index, improves particle size distribution, and significantly enhances mechanical properties such as unconfined compressive strength (UCS) and California Bearing Ratio (CBR). Durability tests show that GSA-treated soils exhibit reduced weight loss under wet-dry cycles, indicating improved durability. However, the effect on permeability varies, with some studies reporting decreased permeability due to void filling, while others note increased permeability from larger pore formation. Compared to traditional stabilizers, GSA requires higher dosages to achieve similar strength improvements but offers substantial cost savings and environmental benefits, reducing stabilization costs by up to 40% and CO₂ emissions by approximately 30%. Future research should explore long-term performance, optimize GSA particle size, combine GSA with other agricultural wastes, standardize production, and conduct life cycle assessments. Overall, GSA presents a sustainable alternative for soil stabilization, turning agricultural waste into a valuable resource for construction.