Influence of freeze-thaw cycles on secondary deterioration of concrete caused by alkali silica reaction

Experiments were conducted for concrete suffered from various freeze-thaw cycles to investigate their damage characteristic under subsequent effect of alkali silica reaction (ASR). Both fast freeze-thaw cycles and accelerated ASR were carried out. Concrete specimens were undergone 30 and 60 freeze-thaw cycles first, then were immerged into 1 mol NaOH solution at 60°C to suffer from ASR. Once a week, the ultrasonic velocity of specimens were measured and transferred into relative dynamic modulus to represent the deterioration of concrete. Experimental results show that initial freeze-thaw cycles induce the subsequent ASR damage and accelerate the deterioration of concrete. The severer the initial frost damage, the severer the later ASR damage. Compared with specimens without initial frost effect, the damage regularities show little change, except the acceleration of the damage rates. The effect of initial freeze-thaw cycles is equivalent to a severer ASR effect later on. The formation of internal defects and change of internal structure caused by the initial effect accounts for the results.