The durability of shotcrete in cold region tunnel: A review

Frost damage is a common problem for tunnels in cold regions. To improve the durability of the shotcrete in cold areas this paper reviews recent research findings, summarizes the common damage and frost heaving process of shotcrete in cold areas, and includes the microstructure changes of shotcrete caused by the freeze-thaw cycles, the main influencing factors of frost durability, the four stages of the frost damage of shotcrete, and primary methods used to improve the frost durability of shotcrete. Suggestions for further research on the frost resistance of shotcrete were provided.