Enhancing the Geotechnical Properties of Oil-Contaminated Soils Using a Hybrid Blend of Rice Husk Ash and Charcoal Powder

Abstract

Petroleum pollution has become a significant concern for public health and infrastructural development. This research was embarked upon to assess the remediation potential of sustainable materials on oil-contaminated lateritic soil. Soil samples contaminated with spent vehicle oil (SVO) were treated with combined rice husk ash (RHA) and charcoal powder (CP) at various quantities. The geotechnical properties (California Bearing Ratio (CBR), permeability, maximum dry density (MDD), optimal moisture content (OMC), and consistency limits) of the natural, contaminated, and remediated soil samples were determined in accordance with ASTM International guidelines. The results gotten from the remediated soil specimens revealed that, the two agricultural products substantially reduced the impact of the SVO on the lateritic soil geotechnical properties. The soil's CBR increased from 6.91 to 17.85% (158% improvement), the permeability declined from 9.19 x10^-8 to 3.11 x10^-8 m/s (195% improvement), while the plasticity index (PI) decreased from 14 to 8% (75% improvement) as the content of the remediating agents increased from 4% to 20%. Interestingly, the results depicted that the stabilized soil can be utilized as sub-grade material in road construction. Remarkably, this research outcome highlights that, in addition to mitigating the SVO effects on the soil, the rice husk ash and charcoal powder were able to enhance the soil's geotechnical properties, rendering it suitable for road sub-grade construction.