Interface shear between different oil-contaminated sand and construction materials

The aim of this paper was to investigating the effects of soil relative density, construction ‎materials roughness, oil type (gasoil, crude oil, and used motor oil), and oil content on the ‎internal and interface shear behavior of sand with different construction materials by means ‎of a modified large direct shear test apparatus. Tests conducted on the soil-soil (S-S), soil-‎rough concrete (S-RC), soil-smooth concrete (S-SC), and soil-steel (S-ST) interfaces and ‎results showed that the shear strength of S-S interface is always higher than the soil-material ‎interfaces. Internal and interface friction angles of sand beds increased by increase in ‎relative density and decreased by increasing oil content. The oil properties (especially ‎viscosity) played a major role in interface friction behavior. Despite the friction angles of ‎contaminated sands with viscous fluids drastically decreased, it compensated by the ‎apparent cohesion and adhesion developed between the soil grains and construction ‎materials. ‎