Mechanisms of internal curing agents and their impact on concrete performance: a review

Water management has become unbalanced due to increased population and construction activities. In construction, water is essential for mixing and curing concrete governing the hydration process. Compared to conventional concrete, internally-cured concrete has the ability to alleviate the rate of water loss and intensifies its water retention capacity by using appropriate types and doses of internal curing (IC) agents. With the use of IC agents, the concrete doesn’t require water for curing (or requires less amount of water) and hence the need of water in the construction industry can be reduced by utilizing the natural water resources for other purposes. The present study reports an in-depth analysis on the utilization of three different IC agents, viz., poly-ethylene glycol, super-absorbent polymers, and Light Weight Aggregates, and their effects on physical, mechanical, durability, and functional characteristics of concrete, along with their mechanisms of actions, advantages, and limitations. The methodology employed for this review involved a structured literature search across major databases (Scopus, Springer, ASCE Library, and Wiley) to gather studies related to the performance of various IC agents in concrete. Key performance indicators such as compressive strength, tensile strength, shrinkage behavior, water absorption, and durability aspects were evaluated. The research shows that IC agents benefit concrete’s mechanical properties, hydration, durability, and crack susceptibility, besides reducing the water consumption for concrete curing and allowing to preserve natural water resources. However, challenges such as the effective dosage and compatibility of IC agents with varying mix designs remain least explored. At low water-binder ratios the effect of IC agents can be better observed, especially in high-strength concretes. The scope of this paper provides insights into the current state of research and development in the field, as well as the potential benefits and challenges associated with the use of IC agents in concrete.