Chloride ion diffusivity of fly ash and silica fume concretes exposed to freeze–thaw cycles

This research focuses on investigating the durability of concretes containing fly ash and silica fume exposed to combined mode of deterioration. For this purpose, the chloride ion diffusivity of concrete was evaluated before and after 300 freeze–thaw (F–T) cycles. It was found that the coefficient of chloride ion diffusivity (CCID) increased as water to cementitious material ratio (w/cm) and air content increased. Test results clearly showed that CCID for all concretes increased after F–T cycles. In addition, concrete incorporating silica fume showed the lowest CCID and highest durability factor (DF), regardless of curing regime, air content, and w/cm. However, fly ash concrete showed good resistance to chloride ion diffusivity before and after F–T cycles when low w/cm as well as a proper curing and air content were provided.