Subcritical crack growth has a pronounced effect on processes such as rock weathering and CO 2 sequestration. The pH dependence of subcritical fracture behavior of the marble has been investigated utilizing the double torsion technique. The subcritical crack growth index ( n ) responded differently to acidic and alkaline solutions. The n values decreased by 7.64–38.37% in acidic environment (pH = 1~6) and increased by 4.12–7.00% in alkaline environment (pH = 10~12) compared to distilled water conditions. SEM–EDS results indicated that the microstructure and the number of dissolution pores on the marble fracture surfaces are dependent on the fluid pH values. In addition, due to the chemical reaction of minerals with hydrochloric acid, the C content on subcritical fracture surfaces increased with increasing fluid pH value, while the opposite trend was observed for Cl element. Predictions of the n value based on mineral dissolution rates indicate that under strongly acidic conditions (pH ≤ 4), the predictive model tends to underestimate n values due to omission of mineral over-dissolution effects. These findings highlighted the crucial role of fluid pH and chemical reactions in the subcritical fracture behavior of marbles, which has important implications for subsurface engineering construction and weathering assessment of historical heritage.
Wang et al. (Thu,) studied this question.