Influence of petrochemical contamination on the geotechnical behavior, shear strength characteristics, and compressibility indices of sandy clay soil

One of the most important geo-environmental issues is the contaminated soils in the construction industry which are caused by the contamination of petrochemicals. In contrast with previous studies which evaluated individual soil properties separately, this study presents an integrated experimental evaluation of index properties, compaction behavior, shear strength, compressibility, permeability and microstructure of a most of the existing studiedly clay soil (CL, USCS) contaminated with diesel fuel at 0%, 2%, 5% and 10% by dry weight, using standard ASTM procedures. The outcomes indicate that the liquid limit, plasticity index, MDD, OMC, cohesion and permeability decreased significantly with contamination while the compression index, settlement and failure strain increased. Carbonaceous coatings of soil particles and measurable loss of crystallinity of clay minerals were confirmed via SEM, EDS, FTIR and XRD analysis, which accounted for the observed decrease in soil strength and resulted in a change from brittle to ductile soil behavior. High regression correlations (R² = 0.94–0.99) were achieved between contamination level and all the measured parameters. The results offer site information for site assessment, foundation design, and remediation planning for petroleum-contaminated sites.