University of Tabriz Journal of Civil and Environmental Engineering 2008-7918 48 91 2018 08 23 The Effect of Silt on Soil-Water Characteristics of Unsaturated Sand The Effect of Silt on Soil-Water Characteristics of Unsaturated Sand 37 45 7910 10.22034/ceej.2018.7910 FA Hadi Aliashrafi Department of Civil Engineering, Urmia University Kazem Badv Department of Civil Engineering, Urmia University Journal Article 2018 10 09 The structure of earth, atmospheric conditions, and hydrogeology, has led that groundwater levels in most parts of the world, including Iran, to decline significantly. This issue causes the large amount of soils above the ground water level to be in unsaturated state.  Various activities associated with soils, such as subsurface explorations, foundation engineering and building constructions in unsaturated soils, etc., necessitates the study of the properties of unsaturated soils. One of the most important and fundamental properties of unsaturated soils is water holding capacity or soil suction. The soil-water characteristic curve (SWCC) has been found to be a conceptual and interpretative tool by which the behavior of unsaturated soils can be understood (Vanapali et al., 1999). The SWCC defines the relationship between soil matric suction (the difference between the air and water pressure in the soil) and the volumetric water content. <br />In this study, the SWCCs of Firoozkoh sand mixed with two silty soils will be investigated to find out the effect of silt on soil-water characteristics of sand in unsaturated state. By conducting this research, one can predict the behavior of natural silty sand for geotechnical applications in practice. In the context of this study, in order to obtain laboratory SWCCs, Tempe pressure cell device will be designed and built. The structure of earth, atmospheric conditions, and hydrogeology, has led that groundwater levels in most parts of the world, including Iran, to decline significantly. This issue causes the large amount of soils above the ground water level to be in unsaturated state.  Various activities associated with soils, such as subsurface explorations, foundation engineering and building constructions in unsaturated soils, etc., necessitates the study of the properties of unsaturated soils. One of the most important and fundamental properties of unsaturated soils is water holding capacity or soil suction. The soil-water characteristic curve (SWCC) has been found to be a conceptual and interpretative tool by which the behavior of unsaturated soils can be understood (Vanapali et al., 1999). The SWCC defines the relationship between soil matric suction (the difference between the air and water pressure in the soil) and the volumetric water content. <br />In this study, the SWCCs of Firoozkoh sand mixed with two silty soils will be investigated to find out the effect of silt on soil-water characteristics of sand in unsaturated state. By conducting this research, one can predict the behavior of natural silty sand for geotechnical applications in practice. In the context of this study, in order to obtain laboratory SWCCs, Tempe pressure cell device will be designed and built. https://ceej.tabrizu.ac.ir/article_7910_f179f229f70b7f7fd40930525d618d4a.pdf