Soil-water characteristic curves from various laboratory techniques

Suctions of two soils (a silty sand of low plasticity and an inorganic clay of intermediate plasticity) at several water contents and dry densities were experimentally measured using null-type axis-translation, filter paper (contact and noncontact), and chilled-mirror dew-point techniques. Additionally, axis-translation and vapor equilibrium techniques were used for establishing the drying suction-water content Soil-Water Characteristic Curves (SWCCs) of the soils. The results from the null-type axis-translation tests generally agreed well with the pressure plate test results at high water contents, whereas differences were noted between the results from the two methods as the water content of the soils decreased. The measured matric suctions using null-type and contact filter paper tests were found to be dissimilar. The total suctions of the soils determined by vapor phase equilibrium techniques (i.e. noncontact filter paper, chilled-mirror dew-point, and desiccator tests) were found to be similar.