Abstract:To solve the serious freezethaw and corrosion damage of machinemade sand concrete for engineering construction in alpine areas, the mineral admixture with high performance was used to modify the durability. The incorporation effects of fly ash, flag powder and the mixtures on frost resistance and impermeability of C40 grade machinemade sand concrete were analyzed. The micromechanism was discussed based on the interfacial zone morphology and pore structure. The results show that the mixing of fly ash and flag powder can significantly improve the durability of C40 grade machinemade sand concrete better than the single one. Mixing with 21% fly ash and 9% flag powder, the frost resistance and the impermeability of C40 grade machinemade sand concrete are greatly improved in both early and late stages, and the interfacial zone morphology and pore structure are significantly improved.