Influence of pre-curing time on the hydration of binder and the properties of concrete under steam curing condition

There is a pre-curing period before the freshly made concrete elements were exposed to steam curing in the steam curing process. In this paper, the influence of pre-curing time on the hydration of binder and the properties of concrete under steam curing condition was investigated. Three binders were used: the pure cement, the binder containing high content of GGBS, and the binder containing high content of fly ash. Three pre-curing times (1, 3, and 6 h) and one steam curing period at 60 °C (over 8 h) were adopted. Results show that pre-curing time has limited influence on the hydration degree of binder, and compressive strength and pore structure of paste. The influence of pre-curing time has limited influence on the compressive strength and chloride permeability of the pure cement concrete and the concrete containing high content of GGBS at whether early or late ages, indicating that the proper pre-curing time can be as short as 1 h for these two concretes. Increasing pre-curing time enhances the late-age compressive strength of the concrete containing high content of fly ash significantly, but it has limited influence on the late-age permeability.