LAUSR

Densely compacted bentonite has been identified as a potential buffer in deep geological repositories as the expansive clay satisfies the hydro-mechanical and physico-chemical functions of the buffer material. A key feature in understanding the hydro-mechanical behaviour of compacted bentonite upon exposure to chemical concentration gradients is to estimate the solute concentrations in micro-pore and macro-pore solutions. This study describes a method based on measurements of total surface area, external surface area, c-axis (2d) spacings and volumetric calculations to determine the solute concentrations in micro-pore and macro-pore solutions of compacted bentonite-enhanced sand (BES) specimens. Results of the study with Barmer bentonite-based BES specimens illustrate that cation concentrations in micro-pore and macro-pore solutions are sensitive to variations in dry density. Further, the exchangeable cation concentrations in the micro-pore solution exceed the soluble salt-cation concentrations in the macro-pore solution of Barmer bentonite.