Quantifying Microstructural Damage of Sandstone after Hydrochemical Corrosion

Abstract

Rock microstructure changes after hydrochemical reactions, which, in turn, leads to deterioration of mechanical properties. Thus, a quantification study on rock microstructural damage after chemical corrosion is necessary. Quantification of the microstructural damage of rocks after chemical corrosion was carried out in this study. We presented a proposal that included formulae for calculating the damage variable by analyzing the porosity changes of sandstone. The plastic deformation of sandstone specimens after soaking in chemical solution was observed. Plastic deformation can be divided into distinct stages over time. Results showed that the prepeak incremental deformation after chemical corrosion was partially due to the increase in plastic deformation before reaching the peak and to the deformation caused by pore compression. Plastic deformation is an indirect indicator of the degree of chemical corrosion of sandstone specimens. After chemical corrosion, the porosity of sandstone specimens changed consistently with the velocity of longitudinal wave. Therefore, the calculation formula of the damage variable can be used to calculate the porosity of sandstone specimens at different time periods. The chemical damage of sandstone specimens was highly consistent with the peak strain. Therefore, the damage variable based on porosity can be used to quantitatively describe the damage caused by chemical corrosion.