Suction Measurement of Bentonite Using Filter Paper Technique

Abstract

Bentonite is used as buffer material in nuclear waste disposal for which its characteristics should be studied. Soil - water characteristics curve (SWCC) is important to understand the unsaturated soil behaviour. The SWCC provides an understanding between the mass of water in a soil and the energy state of the water phase. Curve between soil suction and water content or degree of saturation gives soil-water characteristic curve. In order determine the relationship between suction and water content of unsaturated soil, filter paper technique can be used. The method is simple, economical and provides result with reasonable accuracy. It is an indirect suction measurement technique. Contact and Non – contact methods of filter paper technique determines the total and matric suction values, respectively. In the current study, bentonite was obtained from Bikaner, Rajasthan. Suction versus water content SWCC was established for the specimens of different dry densities and results are calculated using ASTM correlations. Experimentally obtained suction versus water content relationships were compared with that of the results obtained from Fredlund and Xing (1994) and van Genutchen (1980) models. The study revealed that with the increase in water content, suction value decreases but shows no pattern with dry density. Theoretical models were used to find suction values and compared with experimental results whereas van Genutchen model gives more accurate results than that of Fredlund& Xing model.