Geotechnical properties of gas oil-contaminated kaolinite

• The geotechnical characteristics of kaolinite contaminated with gas oil was examined.
• Tests were Atterberg limits, consolidation, direct shear, and unconfined compression.
• Increasing the gas oil content increases the soil's cohesion.
• Increasing the gas oil content reduces the soil's friction angle and compressibility.

The leakage of petroleum products contaminates the soil and changes its physical and mechanical properties. This paper is a part of an extensive laboratory program aimed at promoting greater understanding of the influence of petroleum-derived contaminants on the geotechnical properties of soils. The laboratory tests included basic properties, Atterberg limits, consolidation, direct shear, and unconfined compression tests, all of which were carried out on clean and contaminated kaolinite specimens at the same relative compactions. Contaminated specimens were prepared by mixing kaolinite with different gas oil contents. Results indicate an increase in the cohesion and a decrease in both the friction angle and compressibility of kaolinitic soils with increasing the gas oil content. Results are intended to provide an alternative to the treatment methods currently used in practice for petroleum-contaminated sites and help bridge/narrow the gap between research and practice in environmental protection of the sites.