A Critical Review of the Methodologies Employed for Suction Measurement for Developing the SWCC

Several methodologies have been developed and used by researchers for measuring either total suction ψ (sum of matric suction ψm and osmotic suction ψo), or only ψm. While employing different methodologies for establishing the soil-water characteristic curve, SWCC, there is a possibility that the factors such as the type of the soil suction measured, measurement range, equilibration time, presence of salts or contaminants in the soil etc., may influence it. Thus there is a need to understand the uniqueness of SWCC determined by using some of the commonly adopted methodologies such as insertion tensiometer, a pressure membrane extractor for measuring ψm, and a dew point potentiameter for measuring ψ. For this purpose, two locally available uncontaminated fine grained soils, of entirely different characteristics were considered in this study. In addition, to understand the influence of salt content on the SWCC, another chloride rich soil of marine origin was also considered. The study indicates that the SWCC established by using different methodologies may not be unique and hence due care should be taken while reporting the SWCC of a soil.