The failure of fractured rock masses in slopes due to freeze-thaw processes is a common occurrence in cold regions, leading to significant issues such as soil erosion and landslide disasters, particularly in mining areas. This study utilizes a self-developed true triaxial grouting apparatus to perform full-stress state grouting on freeze-thawed fractured rock. Furthermore, a computational simulation of CT permeability is conducted on the rock mass post-grouting. The primary focus of this research is the quantitative assessment of the waterproofing properties of grout masses utilizing microsilica powder-enhanced cement, along with an analysis of freeze-thaw durability at the grout-rock interface. Experimental findings indicate that microsilica facilitates particle aggregation through nucleation effects and expedites cement hydration via pozzolanic reaction, thereby significantly improving the impermeability and frost resistance of the interface transition zone. Compared to ordinary Portland cement (PC) grouting for waterproofing, the anti-seepage rate is increased by 17% and 20% when microsilica cement is used to grout rock masses that have undergone freeze-thaw cycles of 25 and 45, respectively. The outcomes of this investigation hold substantial importance in enhancing the grouting reinforcement mechanisms of fractured rock masses in cold regions and in implementing targeted preventive and control strategies. Grouting in a freeze-thaw rock mass under a true triaxial state.CT reconstruction of the grouting vein and seepage simulation.Microsilica enhancement of the compactness and freeze-thaw damage resistance of the grout-rock interfacial transition zone.