Investigating the effect of additives’ size on the improvement of the tensile and compressive strengths and deformation characteristics of collapsible soils

In the present study, an experimental investigation was conducted to examine the effect of the size of additives on the improvement of collapsible soils. For this purpose, three collapsible soils with severe collapse potential were selected from Varamin Plain, Iran. The selected soils were then treated in the laboratory by the addition of alumina materials in two sizes of 70 nm (nano-alumina) and 685 nm (micro-alumina) and in different contents to improve their mechanical properties. Soil properties including collapse potential, uniaxial compressive strength, compressive modulus of elasticity, direct tensile strength, and tensile modulus of elasticity were selected as the target parameters for the improvement. These parameters were measured and determined before and after the treatment and the behaviors of treated soils were studied in both compression and tension states. The obtained results indicated that the nanometric and micrometric additives have diverse effects on the performance of the treated soil under compression and tension conditions.