Use of Saturated Saline Solutions in Determining the Water Retention Curve of Compacted Bentonite at Different Temperatures

Vapour equilibrium techniques are usually used in determining the water retention curve of soils for high values of suction. These high values may regularly occur in highly plastic soils such as compacted bentonites, which are often proposed for the engineered barrier in high-level nuclear waste disposal. In the present work, the use of saturated saline solutions for vapour equilibrium techniques at different temperatures was studied. First, a hygrometer was used to measure the evolution of the relative humidity generated by salt solutions at different temperatures. Then, several vapour equilibrium techniques were used for suction control in the determination of water retention curves. The results on relative humidity measurement were in good agreement with that found in the literature. It was observed that the equilibrium time during water retention tests depended on several parameters as the exposition surface of the solution, the dimension of soil samples, and the air circulation, etc. Finally, the water retention curves obtained evidenced the effects of temperature, dry density, hydric history, and negligible influence of the technique used.