Performance of a New Grouting Material under the Coupling Effects of Freeze–Thaw and Sulfate Erosion

In order to study the performance of a new cement-based grouting material under the coupling of freeze-thaw cycle and sulfate erosion, tests related to the performance of the new grouting material were designed and carried out to analyze the damage mechanism of the material under the coupling of freezing and thawing and Na2SO4 solution by testing the mass change, relative dynamic elastic modulus, compressive strength loss and mineralogical and microstructural properties of the new grouting material. The test results show that with the increase in the number of freeze-thaw cycles, the mass loss and compressive strength loss of the specimens in 15% Na2SO4 solution gradually increased, and the relative dynamic elastic modulus showed a decreasing trend. When the freeze-thaw cycle number was 30, the mass loss rate, compressive strength loss rate and relative dynamic elastic modulus of the specimens in Na2SO4 solution were 4.17%, 24.59% and 84.3%, respectively, which showed better erosion and frost durability. Mineralogical and microstructural analysis showed that SO42- in solution led to the decomposition of the C-S-H gel and the formation of CaSO4•2H2O inside the specimen, and the internal deterioration was exacerbated by the widening of the crack width being aggravated, suggesting that the rate of material deterioration under the coupling of the two factors increased.