Restrained Shrinkage Cracking and Dry Shrinkage of Rapid-Set Prepackaged Cementitious Materials

Abstract

The dry shrinkage characteristics of 23 rapid-set prepackaged cementitious materials collected from the current market have been investigated in this study. The materials showed various trends and rates of free dry shrinkage strain development. Overall, most materials had the free dry shrinkage of less than 0.05% at 28 days; however, only materials with the 28-day free dry shrinkage of less than 0.025% were observed to exhibit a low risk of restrained shrinkage cracking. The restrained shrinkage cracking typically occurred within a week after casting primarily because of the rapid growth of dry shrinkage during this period. A higher free dry shrinkage strain or a higher rate of free dry shrinkage strain development at the early age normally resulted in an earlier formation of cracking and a larger crack size during the restrained shrinkage test. Coarse aggregate extension reduced the free dry shrinkage and the risk or the size of restrained shrinkage cracking or delayed the time of restrained shrinkage cracking.