Durability of fly ash concrete exposed to slow freeze-thaw cycles

Experimental research was carried out to investigate the effect of fly ash on the durability of concrete subjected to slow freeze-thaw cycles. Particular emphasis was given to the effect of fly ash replacement level (up to 65%) on the durability of air entrained concrete (AEC) and non-air entrained concrete (NAEC). Two groups of tests were conducted. In the first group, concrete specimens from all mixes were exposed to slow freeze-thaw cycles at an early age of 7 days. In the second group, the freeze-thaw cycles started after 28 days of curing. The deterioration, weight loss and residual strength of concrete specimens were assessed after cycles of slow freezing and thawing. The results showed that fly ash has a significant effect on the durability and residual strength of concrete exposed to freezing conditions. In addition, the initial curing period before exposing concrete specimens to freeze-thaw cycles was one of the most significant factors affecting the freeze-thaw durability of fly ash concrete. Compared to Portland cement concrete, air-entrainment is more vital for fly ash concrete if structures are expected to experience freeze-thaw cycles during their lifetime.