Influence of water on deformation and failure of gypsum rock

While water is known to significantly reduce the strength of rocks, there remains a paucity data on water-weakening gypsum. Here, we quantify in natural gypsum facies from Monferrato (Italy) by performing experiments nominally dry, oil-saturated, and water-saturated samples. Uniaxial conventional triaxial revealed significant as well strong strain-rate dependence uniaxial compressive strength. Moreover, creep tests showed time-dependent deformation samples saturated with sulphate over-saturated water, but not dry oil-saturated The phenomenology similar that observed other rock types consistent stress-corrosion microcracking, which supported our microstructural observations. However, systematically recorded more inelastic strain deformed at low strain-rates suggesting additional mechanisms were also active. Comparing new short-term published results for types, conclude that, when equilibrium rock, weakening notably higher than rocks partially due reduction fracture toughness presence water.