Passive remediation with colloidal silica effect on shear strength properties of oil-contaminated Bushehr carbonate sand

Crude oil is one of the soil and water pollution sources which changes the geotechnical properties of the soil via both physical and chemical processes. Carbonate sand which found in oil-rich and continental regions is exposed to oil pollution so that studying the effect of oil and petroleum products contamination is unavoidable. On the other hand, injecting colloidal silica solution, stabilization and improvement of oil-contaminated sand has been investigated broadly. In this research, several triaxial undrained-unconsolidated tests were conducted to investigate the shear strength of carbonate sand contaminated with crude oil as well as contaminated sand stabilized by colloidal silica injection. The results showed that oil pollution reduced the maximum shear strength and the friction angle of carbonate sand, as well as a significant decrease in elasticity modulus while oil content increased. In injected specimens, colloidal silica increases the shear strength, cohesion and stiffness significantly relative to the oil-contaminated ones.