New interpretation of alkali-silica reaction and expansion mechanisms in concrete

A better understanding of alkali-silica reaction and expansion mechanisms is necessary to enable the controls on deterioration processes to be established more accurately, and to help predict future structural behavior. To this end a series of long-term experiments were set up to determine the effects of relative humidity and temperatures in the range 0-38°C on several concretes affected by ASR (Alkali-Silica Reaction). Results have indicated that in certain circumstances concrete behavior may differ substantially from that predicted by the generally accepted model of deterioration. In particular, it has been found that in some concretes, elevated temperatures may actually increase the cut-off humidity and significantly reduce the ultimate damage caused by ASR. The classic model of alkali-silica reaction has been reviewed in the light of these findings.