Effect of Shape Discrepancies on Strength of Binary Soils

The properties of host sand dominate the soil structure at a low fines content and thus affect the overall mechanical behavior of binary soils. We performed a series of drained triaxial shear tests under different effective confining pressures and fines contents to investigate the stress-dilatancy behavior of sand-silt mixtures by mixing three types of host sand with a given non-plastic silt. We found that the presence of fine particles generated a variable effect on the drained strength, volumetric strain, peak-state friction angle, maximum dilation angle, and critical-state friction angle, contingent on the disparity in shape between the sand particles and the fine particles. Furthermore, we proposed a modified stress-dilatancy equation. In this equation, the slope was independent, while the intercept was incorporated with the combined effects of the host sand shape and the fines content.