Valorization of Spent Engine Oil Contaminated Lateritic Soil with High Calcium Waste Wood Ash

Lateritic soils often become contaminated with oil of hydrocarbon origin resulting from anthropogenic activities such as operation of mechanic workshops on lateritic soil deposits, leakage of underground petroleum and oil storage tanks, accidental spillage of crude oil and petroleum product. Whenever such areas will be used either as construction sites or borrow pits, concern is usually raised on the impact of the oil contamination on the soil. This study therefore examined the impacts of waste wood ash on the stabilization of the spent engine oil (SEO) contaminated lateritic soil, using 0 - 9% of waste wood ash by mass of soil sample in 3% step concentration. Sieve analysis, consistency limit, compaction and uniaxial compressive strength tests were carried out on the stabilized soil specimens. The results revealed that the addition of the waste wood ash improved the liquid, plastic and shrinkage limits, but decreased the plasticity index of the lateritic soil. The maximum dry density and uniaxial compressive strength of the lateritic soil increased from 0 to 6% addition of waste wood ash, which gives an indication that waste wood ash is significantly effective up to 6% addition. Based on this study, addition of 6% waste wood ash by weight of the dry soil is therefore recommended for the stabilization of the SEO contaminated soil in order to improve its consistency and strength characteristics for its use as a highway material.