The damage mechanism and deterioration characteristics of acid-corroded sandstone: an experimental study

Because of the long-term interaction with polluted groundwater, the physicomechanical characteristics of rock have deteriorated. In this paper, experimental investigations were conducted to shed light on the effects of acid types, pH values, and immersion periods on physicomechanical properties, microstructure change, and energy characteristics of sandstone. Besides, the essence of mechanical deterioration of corroded sandstone was revealed based on the energy evolution law, and the chemical damage mechanism of sandstone subjected to acid solutions was concluded in the theoretical context of chemical kinetics. The results showed that acid corrosion would cause the increase of P-wave velocity, porosity, peak strain, the decrease of characteristic stresses, elastic modulus, strain energy, and the change of internal microstructure and mineral content. The same exponential function could express the relationship between damage variables based on P-wave velocity or porosity and corrosion time. Moreover, the effects became evident as pH values declined and immersion periods extended, especially for HCl solution.