Sandstone weathering under dry-wet cycling in NaCl solution

Due to precipitation and groundwater level changes, rocks often cycle between dry and wet states. This can cause weathering, which may be exacerbated by the presence of salt. Sandstone is a widely used material in ancient and modern buildings, so the effects of salt during wet-dry cycling are, therefore, of great interest. It is also important in geotechnical engineering to understand its effects on the physical properties of rock. In this paper, sandstone from Wanzhou District, Chongqing, China, was soaked in 0%, 2%, 4%, 6%, or 8% NaCl solutions for 200 dry-wet cycles. The quality, chromaticity, and roughness of the sandstone were measured, and changes in the internal pore structure were studied using nuclear magnetic resonance. The sandstone exhibited three stages of mass loss: a decrease (0-10 cycles), a slow increase (10-140 cycles), and a sharp increase (140-200 cycles). In the third stage, the chromaticity, roughness, porosity, and pore size change significantly. Higher NaCl concentrations cause more serious rock weathering. Salt crystallization increases the pore size, which indirectly accelerates the weathering rate.