Hydration kinetics, change of relative humidity, and autogenous shrinkage of ultra-high-strength concrete

This research forms part of a vast experimental program designed to investigate the shrinkage and creep of compact reinforced composite (CRC), which is an ultra-high-strength concrete. In this paper, only results relating to autogenous shrinkage are presented. While shrinkage deformations were measured, cement hydration, pozzolanic reactions, and pore structure of concrete also were monitored to characterize the microstructural evolution of material. Very high autogenous shrinkage at an early age that stops 10 days after casting was observed. As far as we know, this sudden break in shrinkage kinetics has never been observed before in cement-based materials. The autogenous relative humidity measurements show high self-desiccation within the CRC. A relationship between autogenous shrinkage and self-desiccation of CRC is established and discussed.