Influence of Exposure Conditions on the Efficiency of Internal Curing in Concrete

Abstract

Abstract Internal curing uses pre-wetted fine lightweight aggregate (LWA) to supply cementitious systems with water. This increases the hydration of cement and reduces the influence of self-desiccation resulting in concrete with increased compressive strength, reduced permeability, and reduced shrinkage potential. Whereas these mixtures have shown great potential, there has been considerable debate on how internally cured samples should be conditioned during laboratory testing. This paper explores the influence of sample storage on the properties of mixtures prepared with and without internal curing. Samples were prepared and cured in different exposure conditions including environments in which: (1) moisture is supplied either via soaking or misting, (2) moisture is neutral, and (3) moisture loss is allowed. Experimental results show that when adequate external curing water is supplied, only limited benefits are seen from internal curing. The benefits of internal curing are more evident in systems that do not receive additional external curing water (sealed) and even more so when systems are exposed to external drying. Conditions where inadequate external curing water is supplied may be more representative of what would be experienced in the field.