Abstract
In this study, the chloride ion binding ability of sulfoaluminate cement concrete (SAC) containing different mineral admixtures was investigated. The effects of chloride concentration, curing age, and the type and amount of mineral admixture on the chloride binding rate of SAC were analyzed. It was found that the content of water-soluble chloride ions in SAC decreased with the increase of curing age, while the chloride binding ratio increased accordingly, indicating that its resistance to internal chloride permeation increased. The addition of fly ash (FA) and ground granulated blast furnace slag (GGBS) can significantly improve the chloride binding capacity of SAC, and the chloride binding rate increases to 46.6% with 20% of FA and 38.7% with 40% of GGBS. The effects of mineral dopants on the microstructure and phase composition of SAC were further investigated by X-ray diffraction (XRD) analysis. The results showed that the addition of FA and GGBS promoted the formation of C-S-H (calcium silicate hydrate) gels and improved the resistance of SAC to chloride ion penetration. On the other hand, the excessive addition of silica fume (SF) led to a decrease in the chloride binding capacity, whereas a moderate amount of limestone powder (LP) improved the chloride binding capacity.