Evaluation of the frost resistance of sandstones from the aspect of frost deformation

Frost resistance of rocks is an important index for geological engineering in cold regions. The present evaluation indexes mainly include mass loss ratio and frost resistance coefficient. However, the measurement of them is time-consuming and laborious. In this study, a comprehensive study was conducted to easily evaluate the frost resistance of 14 sandstones from different provinces of China. The mineral composition and initial structure were obtained through X-ray diffraction (XRD) test and 3D optical microscopy, and mechanical strength tests were also performed to assess the durability under freeze–thaw conditions. Various indexes such as mass loss ratio, freeze–thaw coefficient, softening coefficient, water absorption content, and water saturation coefficient were measured for evaluating the frost resistance according to the conventional evaluation method. In addition, the strains of sandstone during freeze–thaw process was also measured, and the frost strain shows significant freezing expansion and thawing shrinkage characteristics for the saturated sandstones with porosities larger than 5%. Based on the above research, a new evaluation method using peak strain and residual strain as evaluation criteria is proposed. This method categorizes the frost resistance into three levels: poor, medium, and good, making it easier to assess their suitability for different engineering geological conditions. The findings of this study not only provide valuable insights into assessing the frost resistance of sandstone but also contributes to a better understanding of the freeze–thaw damage from the aspect of frost deformation.