Artificially sedimented specimens of Wyoming bentonite (Volclay) were used to investigate the effect of physico-chemical variables on the shear strength properties of montmorillonite. Triaxial compression tests were performed on calcium and sodium montmorillonite at various electrolyte concentrations.The influence of the type of adsorbed cation and concentration of electrolyte in the free pore water on the shear strength of montmorillonite was investigated using undrained triaxial compression tests with pore water pressure measurements. The effective-stress failure envelopes of calcium and sodium montmorillonite were curved; in the range of stress studied their slopes decreased from 15º to 10º and 4º to 0º, for calcium and sodium montmorillonite respectively. The decrease in slope of the effective-stress failure envelope could be due to greater parallelism of clay plates at higher consolidation pressures. A series of drained triaxial compression tests using calcium montmorillonite yielded the same effective-stress failure envelope obtained using undrained tests. Consolidated undrained tests on calcium montmorillonite showed that simply over-consolidated specimens had strength higher than normally consolidated specimens at the same effective normal stress at failure.
ASJC Scopus subject areas
- Geotechnical Engineering and Engineering Geology
- Earth and Planetary Sciences (miscellaneous)