Supporting Data: Effect of various pore fluids on the strength of granite

Laboratory three-point bending experiments are carried out to evaluate the effect of various fluids on the tensile strength of granite. The fluids used to saturate the granite include distilled water, hydrochloric acid (HCl), sodium hydroxide (NaOH), kerosene, and hydraulic oil. Compared to dry granite specimens, water, HCl, NaOH, kerosene, and hydraulic oil reduce the tensile strength of granite by 26%, 37%, 28%, 23%, and 41%, respectively. The test data indicates that aqueous and non-aqueous solutions have a similar effect on reduction of the tensile strength as long as viscosity is similar. Fluid viscosity, on the other hand, has a strong impact on the strength with higher viscosity leading to greater strength reduction. The experiments suggest that chemical fluid-rock interaction plays a minimal role in these experiments where failure occurs within seconds to minutes from the time loading commences. On the other hand, the mechanical influence of the fluid, such as lubrication of grain boundaries and/or local pore pressure generation appears to play a more important role in the determination of the strength of granite.