hamed pouralizadeh - m.sc.studen department of civil & environmental engineering amirkabir university of technology tehran iran
taghi ebadi - assistant professor department of civil & environmental engineering amirkabir university of technology tehran iran
amirhossein mohammadi - ph.d studentdepartment of civil & environmental engineering amirkabir university of technology tehran iran
bijan khatibi - m.sc.student department of civil & environmental engineering amirkabir university of technology tehran iran

Effect of bentonite addition to sandy soil was assessed in terms of compressibility and shear strength behavior. The experiments were carried out by synthetic polluting dry sandy soil by 0, 2.5, 5, 7.5, 10% w/w crude oil with different bentonite dosage (0, 5, 10, 15, 20% w/w). Laboratory experiments were carried out using standard proctor compaction and direct shear tests apparatus. Results of compaction tests indicated that at a fixed bentonite content, with increasing crude oil content, the maximum dry density increases, while the optimum water content decreases. Similarly, at a fixed contaminant dosage, increasing the bentonite content in the soil leads to increase in soil maximum dry density and the optimum moisture content. Moreover, direct shear tests revealed that at a specific bentonite content, higher contamination causes lower internal friction angles. Additionally, the shear test results implied that presence of bentonite and oil pollution in the soil, leads to relatively higher cohesion values compared to clean sample with 0% bentonite which is the result of oil viscosity and natural cohesion of the bentonite.

Bentonite, Compressibility, Shear strength, Oil-contamination, Sandy soil