Experiment study on the failure mechanism of dry-mix shotcrete under the combined actions of sulfate attack and drying-wetting cycles

The damage process and failure mechanism of shotcrete under the combined actions of sulfate attack and drying-wetting cycle were investigated. The results indicated that shotcrete was inherently more inhomogeneous, the compact area and defect region exhibited different erosion mechanisms and failure forms. The connected and loose defects could accelerate the intrusion of external sulfate ions and the growth of corrosion products. The localization and directivity of defects would lead to the localized distribution of expansive stress. Hence, the crack in defect region developed significantly faster and was the key factor that limited the durability of shotcrete under sulfate attack.