Dry–Wet Cyclic Sulfate Attack Mechanism of High-Volume Fly Ash Self-Compacting Concrete

High-volume fly ash replacing cement helps to improve the fluidity, volume stability, durability, and economy of self-compacting concrete (SCC). Sulfate attack is most common form durability damage hydraulic concrete; in particular, performance degradation at water level change position more significant. Therefore, research on influence effect mechanism great significance. In this paper, regularity SCC physical mechanical properties with replacement percentage dry–wet cycles were studied by 60 sulfate test. The 6 h electric flux, MIP, SEM used study cured for 56 days, which had also been attacked sulfate. results show that increased first then decreased attack. After 10–15 cycles, corresponding slightly, gradually. When content was 40%, corrosion resistance coefficient, relative dynamic elastic modulus, flexural strength retention higher than those control specimen. However, when 50%, they close deteriorated obviously further addition ash. For pore sizes range 120–1000 nm, porosity days inversely proportional flux properties, indicating large pores decisive factor affecting chloride ion permeability resistance. incorporation can products destruction mechanism. 40% specimen dominated ettringite crystallization expansion, while a 50% 60% no obvious products, microstructures became looser. appropriate could significantly SCC.