Geotechnical Stabilization Potential of Cement Admixed with Rice Husk Ash on the Crude Oil Polluted Laterite Soil: A Case Study of Ebendo, Delta State, Nigeria

Abstract

Crude oil pollution of the environment is one of the greatest concerns to Nigeria’s oil-rich Niger Delta and most oil producing regions of the world, with far-reaching effects on the ecosystems. In this study, the influence of oil pollution on geotechnical properties of laterite soil and possibility of stabilization with rice husk ash (RHA) and ordinary Portland cement (OPC) were investigated. Soil sample categorized as A-2-6 and CL was artificially contaminated with 0, 2, 4, 6, 8, and 10% crude oil. The consistency limits, specific gravity (SG), Compaction, Uniaxial compressive strength (UCS) and California Bearing Ratio (CBR) tests were carried out on both uncontaminated and contaminated soil samples. The 10% contaminated specimen was further stabilized with admixture of OPC and RHA using different percentages (0-10%) by mass of soil. A significant decrease in SG, maximum dry density (MDD), CBR and UCS was revealed but with an increase in consistency limits and optimum moisture content (OMC) as the volume of crude oil increased from 0 to 10%. However, stabilization of the contaminated soil with OPC and RHA improved the soaked CBR and UCS. The addition of OPC (0-10%) enhanced the UCS and CBR of the 10% polluted soil from 25-119 kN/m2 and 2-18.3%, respectively, while the treatment with RHA increased the UCS and CBR values from 25-60 kN/m2 and 2-4.4%. The results of research clearly show that oil contamination had considerable influence on soil properties but addition of 10% RHA or 8% OPC can be adopted to restore and enhance the geotechnical properties of the polluted laterite soil.