Soil water retention curve of silty sand – experimental investigation using different laboratory methods

Most of the infrastructure investments and earthworks not requiring deep foundations are usually designed in the vadose zone to avoid excessive groundwater-structure interactions. The mechanical behaviour of soil material, under partially saturated conditions, is greatly influenced by pore-water tension, known as soil suction, and the characteristics of the Soil Water Retention Curve (SWRC). In the present paper, the SWRC of a silty sand was determined using two different experimental methods. In the first method, a modified pore water pressure transducer was used for suction monitoring, while the specimen was allowed to change its moisture content by natural evaporation. For the second method, a modified consolidation cell fitted with a high air entry value ceramic disc on the base pedestal was used. Suction was applied using the axis translation technique by utilising pore air and pore water pressure controllers, while moisture was monitored using a volumetric measurement system. Through the determination of the SWRC for the silty sand, this paper intends to compare the abovementioned testing methods basedon the produced SWRCs and to reveal advantages and limitations