LAUSR

Abstract The current study aims to investigate the influence of the addition of fine materials on the engineering properties of silty sand soil. An intensive laboratory study of saturated and unsaturated silty sand soil treated with different percentages of fine materials of clayey soil (passing sieve #40 and ranging of 5, 10, 20, 40 and 80%) was investigated by conducting Oedometer and permeability tests. Unsaturated permeability and soil–water characteristics curve (SWCC) were also examined. Test results show that soil plasticity increases as the fine materials increase. The maximum dry unit weight (γdmax) increased up to 10% of fine materials then decreased, while the optimum moisture content (OMC) increased along with the increase of fine materials. One dimensional compression test results show that the fine materials influence the compression characteristics and the compression index of the soil samples increased with the increase of fine materials. In contrast, the saturated permeability sharply decreased as fine materials were increased. For higher percentages of fine content, the reduction in soil permeability becomes less significant. In addition, the unsaturated permeability decreases with fine materials and suction pressure increases. The effects of fine materials are more evident at lower suction pressures. Furthermore, the water holding capacity and air entry value increased with the addition of fine materials.