Experimental investigation of the effects of gas oil and benzene on the geotechnical properties of sandy soils

In recent years, there has been a dramatic increase in using oil hydrocarbons such as gas oil and benzene as the primary source of energy in transport and industrial sectors. Soil contamination is a significant public health problem. The contamination of soils by different hydrocarbons is increasingly recognized as a serious, worldwide public health concern and has become a central issue for geotechnical engineers. However, to our knowledge, no systematic studies have been conducted to investigate the effects of gas oil and benzene contamination on the geotechnical properties of sandy soils. Therefore, the present study investigates the impact of different percentages of benzene and gas oil contamination (0, 5, 10 and 15%) by the dry weight of two types of sandy soils on geotechnical properties of soils using several laboratory tests such as direct shear, compaction and permeability tests. The compaction test results showed that optimum moisture content declined in oil-contaminated samples. Moreover, the maximum dry density increased up to 5% oil content and then decreased by adding oil to the sandy soils. The direct shear test indicated that cohesion increased and friction angle decreased after oil contamination. The permeability test result revealed that contamination caused a decrease in permeability of sandy soil and the change was a function of oil content and viscosity of oils.