Effect of Crude Oil Contamination on the Geotechnical Properties of Kaolinite Clay soil in the Road

Crude oil and its derivatives infiltrate into the soil in the communities where oil exploration activities are prevalent. The leakage of crude oil, in addition to negative environmental effects such as groundwater contamination, causes changes in the geotechnical characteristics of the soil. In granular soils, these changes occur mostly in physical properties while in fine-grained soils, the texture and structure of the soils are mainly altered. It is important to note that these changes in characteristics of the soil layer could reduce the bearing capacity and increase the overall and relative the settlement of the foundation underneath the structures and may lead to an ultimate collapse. This research work aimed at experimental investigation into the effect of crude oil contamination on Atterberg limits, specific gravity, compaction, strength and permeability of Kaolinite clay soil. Numerous Soil samples were prepared from contaminated soil having various percentages of crude oil and were tested subsequently. The results of the experiments showed that the liquid and plastic limits and plasticity index decreased with increase in crude oil content. Also, as the crude oil content in the contaminated soil increased, the maximum dry unit weight of the soil increased while the optimum moisture content decreased. In addition, increasing contamination caused the permeability coefficient of contaminated soils to decrease. Increasing the amount of oil had also a different effect in the uniaxial test of contaminated soils. It was observed that increase in contamination content up 2% would cause the uniaxial strength to increase. However, more increase in the contamination content, 4% and 6%, reduced the rate of increase in the uniaxial strength of soil.Soil contaminated with crude oil is essential be stabilization or modified before use in construction.