Artificially sedimented specimens of Wyoming bentonite (Volclay) were used to investigate the effect of physico-chemical variables on the consolidation properties of montmorillonite. One-dimensional consolidation tests were performed on calcium and sodium montmorillonite at various electrolyte concentrations. The influence of pH and organic pore fluids on the consolidation properties of montmorillonite was also investigated. The consolidation curves of calcium montmorillonite were essentially independent of both the electrolyte concentration in the free pore water and the pH of the suspension from which the specimens were sedimented. The influence of pore water electrolyte concentration on the swelling curves of calcium montmorillonite was much smaller than would be predicted from the Gouy-Chapman double layer theory. The consolidation and swelling curves of sodium montmorillonite were affected by the concentration of electrolyte in free pore water and there was reasonable agreement between the measured swelling curves and the double layer theory. Consolidation tests in which organic pore fluids were used demonstrated that swelling of montmorillonite is caused by either adsorption of the pore fluid or formation of diffuse double layers. The coefficient of permeability of the sodium montmorillonite in water was as low as 2 x IO-l2 cm/s. The coefficients of permeability were higher for the montmorillonite in ethanol than in water, and considerably higher values were obtained when the pore fluid was non-polar, all compared at the same void ratio.
ASJC Scopus subject areas
- Geotechnical Engineering and Engineering Geology
- Earth and Planetary Sciences (miscellaneous)