Evaluation of strength properties of oil-contaminated sands upon stabilisation with laterite soil

Abstract

ABSTRACT Commercial decontamination procedures of oil contaminated sands can be costly. In this study, the inexpensive laterite soil was used as the stabilization additive, which brought notable results in geotechnical strengths, permeability, penetrability by a standard plunger, and surface morphology. To simulate contamination, clean sands were blended with motor oil where loses in geotechnical strength and permeability decreases were observed.Subsequent stabilization by the laterite soil recovered the strengths where maximum dry unit weights, friction angles cohesions and California bearing ratios (CBR) were enhanced; the permeability however decreased further. Adding 15% laterite soil to sands with 3 to 10% oil contents increased friction angles by 9.5 to 14.4%. For sands with 5% oil, treatment with 15 and 20% laterite soils increased CBR by 27 and 36% respectively; the latter figure indicates strength even better than that of the uncontaminated.The scanning electron microscopy (SEM) showed morphologies of soil grains drenched in oil and the subsequent rejuvenation brought by the stabilization. Rather than neglected, oil-contaminated sands, after stabilisation by laterite soil, are now feasible for use as subgrade or subbase material, or the fine aggregate of hot-mixed asphalts.