Restrained shrinkage behavior of ambient cured alkali activated concrete

Abstract

This experimental study aims to evaluate the shrinkage cracking potential of Alkali Activated Concrete (AAC) under restraint conditions. The work also looks at the various parameters that effect the cracking potential of such concrete under varying degree of restrained conditions using the ASTM and AASHTO rings. Furthermore, the effect of curing conditions and activator solution ratio on the cracking potential of AAC is also reported. The results indicate the risk of cracking is governed by many competing properties, including strength and stiffness development, free shrinkage potential, degree of restraint and relaxation properties of the mix. Wet curing improved the strength development of the mixes. Nonetheless, extending the wet curing beyond 3-days did not significantly improve the cracking resistance of the restrained samples. The results suggest that a higher alkali activator ratio is more suitable for structural elements under high degree of restraint while a lower alkali activator ratio may be suitable for structural elements under low degree of restraint.