Abstract: Mineral admixtures could enhance the corrosion resistance of concrete to address the salt corrosion of concrete structure in saline soil region of northwest China. In this paper, we examine the influence of admixtures on concrete’s resistance to sulfate corrosion via SEM (Scanning Electron Microscope) and XRD (X-Ray Diffraction) based on the prerequisite that concrete strength is required in advance in specific projects, e.g., at C35 grade. In the test, concrete specimens dosed with single (fly ash or slag powder), double (fly ash and silica fume, or slag powder and silica fume), or triple (fly ash, slag powder, and silica fume) admixtures in different proportions have undergone drying and wetting cycles in sulfate solution. We also investigate concrete’s resistance to chloride ion diffusion using fast chloride ion transfer coefficient and electric flux method. Research findings suggest that at given concrete strength, the climbing of admixture content improves concrete’s ability of resisting sulfate corrosion and chloride ion diffusion. The effect of fly ash is better than that of slag powder. Combining the admixtures could ameliorate concrete’s pore structure and hydration product structure, and boost concrete’s corrosion resistance.

Key words: concrete, corrosion resistance, mineral admixture, wetting-drying cycles, sulfate corrosion, SEM, XRD, chloride ion penetration