Lime treatment of a diesel-contaminated coarse-grained soil for reuse in geotechnical applications

Abstract Potential reuse of oil-contaminated soils guidance policies are demonstrating ways to reuse these materials in engineering applications. However, the engineering properties of these materials are highly altered after contamination. Alternatively, chemical stabilization treatments can improve oil-contaminated soil properties for its reuse in geotechnical applications. This study investigates the effect of a diesel contamination on a coarse-grained soil and assesses the viability of a lime treatment. Laboratory tests included pH, Atterberg limits, compaction, unconfined compression strength (UCS), California Bearing Ratio (CBR) and tensile strength, RX-diffraction and scanning electron micrographs before and after lime treatment. Tests were performed on natural soil, diesel-contaminated soils (2, 4, 8, 12, and 16% of diesel) and lime treated diesel-contaminated soils (2, 4, 6 and 8% of lime). Diesel drastically changed soil plasticity and strength properties. Lime stabilization of diesel-contaminated soils was efficient to recapture soil natural properties with low lime contents. The influence of oil and lime in soil mechanical properties and mineralogical characteristics was evidenced in this study. The presence of oil drastically altered soil mechanical properties. Crystallization of calcite was present in both natural and oil-contaminated soils treated with lime, increasing particles flocculation. The presence of oil favored dolomite formation. Lime was significate in enhancing oil-contaminated soil mechanical properties, such as UCS, indirect tensile strength and CBR, mainly due to carbonation reactions. Oil-contaminated soil mixtures showed increase in mechanical properties after lime treatment and curing period.