Experimental Studies on the Effects of Cyclic Freezing–Thawing, Salt Crystallization, and Thermal Shock on the Physical and Mechanical Characteristics of Selected Sandstones

Rocks are used in engineering works as monuments, building stones, and architectural covering stones. Their weathering behaviors and physical and mechanical properties are the most important factors controlling their suitability as building stones. The aim of this study is to evaluate the weathering behaviors of sandstones from the Qazvin area (western Iran). In total, nine sandstones (A, B, C, CG, S, S₁, Min, Tr, and Sh) were analyzed. Accelerated weathering processes, namely freezing–thawing (F–T), salt crystallization (SC), heating–cooling (H–C), and heating–cooling–wetting (H–C–W), were used. Sandstones were subjected to 60 cycles of F–T, H–C, and H–C–W and 20 cycles of SC, and changes in characteristics including weight loss (%), P-wave velocity loss (%), and changes in uniaxial compressive strength (UCS) and point load strength were recorded after different numbers of cycles. The results from our laboratory studies indicate that rocks from the same stratigraphic layer can show major differences in weathering properties, and their sensitivity to these processes are different. Also, it was found that the thermal behavior of sandstones under wet and dry conditions were different. In the next stage of this study, a decay function model was used to statistically evaluate the disintegration rate. This model showed that the disintegration rate was higher for salt recrystallization compared with F–T, H–C, and H–C–W processes.