Geotechnical Evaluation of Wood ash Stabilized Clay Soil

This study examines the effects of wood ash on the index and strength properties of clay soil. The properties of the natural clay soil were determined. Moisture content test, sieve analysis , specific gravity test, Atterberg’s limit test and unconfined compressive strength (UCS) were carried out on the clay soil sample. The proportion of wood ash content used are 0%, 5%, 10%, 15%, 20% , 25% and 30% respectively as wood ash –soil mixtures. The investigated clay soil has natural moisture content of 9.2% , specific gravity of 2.72 and 68 % weight of Silty- clay particles. The results of Atterberg’s limit shows liquid limit and plastic limit increases with wood ash addition while the plasticity index decreases with higher wood ash content. Decrease in Plasticity limit is an indication of reduction in expansion potential of the clay soil. The OMC increase with wood ash addition while the MDD decreases from 1.77 to 1.65 with higher wood ash content. The UCS increase significantly from 163.7 to 209 kN/m2.. Therefore, wood ash can be used as partial replacement for cement and lime.