Abstract
Abstract High-performance concrete (HPC) and ultra-high-performance concrete (UHPC) are increasingly gaining attention in the construction industry due to their mechanical properties and improved durability compared to conventional concrete mixtures (typically with water-to-binder ratios ≥ 0.4). However, one of the major concerns of low water-to-binder ratio (w/b) mixtures including HPC and UHPC is the autogenous shrinkage due to self-desiccation, which occurs especially during the early age of the hydration process of cementitious materials. To address this issue, different factors influencing autogenous shrinkage such as w/b, cement composition and fineness, supplementary cementitious materials (SCMs), addition of fibers, and chemical admixtures have been studied extensively. In recent years, internal curing (IC) has emerged as a promising shrinkage mitigation technique to supply additional curing water within the concrete matrix, thus mitigating early-age autogenous shrinkage and enhancing durability. This paper provides a comprehensive literature review to elucidate the mechanisms of autogenous shrinkage, the factors influencing autogenous shrinkage, and available solutions to mitigate early age autogenous shrinkage. This paper also reviews the types of IC agents that are currently in use and the factors affecting their performance, such as their absorption and desorption capacities, particle size, porosity, and the recommended dosages. By comprehensively investigating existing studies, this review presents the governing mechanisms of autogenous shrinkage, and highlights limitations in current prediction models. The insights aim to support improved design of shrinkage mitigation strategies in practice and guide future research toward more reliable prediction and mitigation of autogenous shrinkage in low w/b cementitious systems.