Crystallization characteristic of sandstone under capillary salt weathering test using different salt property and temperature

This work aimed to explore the influences of different salts and temperatures on the salt weathering of sandstone in the Nankan Grotto. Capillary salt weathering tests were designed under different conditions. The geochemical, physical, and mechanical properties of sandstone were also analysed. After the tests, the electrical conductances (EC), anion concentrations, masses, P-wave velocities, and porosities of specimens increased as the test temperature was changed from 15 °C to 35 °C within individual experimental settings. Under 6% Na2SO4 + 3% NaNO3 condition, only Na2SO4 exerted crystallization pressure, which exceeded the tensile strength of Nankan sandstone (2.20 MPa). Under 3% Na2SO4 + 6% NaNO3 condition, NaNO3 crystallized at 25 °C and 35 °C, and Na2SO4 crystallized at 35 °C. Their crystallization pressures exceeded the tensile strength of Nankan sandstone. Temperature influences the physical properties of a salt solution, which determines the salt weathering intensity. Our research suggests that salt weathering issues in grottoes should be evaluated in different seasons.