Cement Hydration Rate of Ordinarily and Internally Cured Concretes

Abstract

In the present paper, adiabatic temperature rise test was used to evaluate the effect of internal curing on cement hydra-tion rate and final degree of hydration in normal and high strength concretes. In the experiments, emphases were placed on the impacts of internal curing and water to cementitious material ratio on the adiabatic temperature rise characteristics. Two kinds of concrete, ordinarily cured concrete and internally cured concrete were used in the experiments. In each kind, four concrete mixtures with water to cementitious material ratios of 0.20, 0.30, 0.43 and 0.62 were used. The test results show that internal curing with PSLWA increases temperature rise of concrete, whatever the con-crete strength is low or high. Internal curing can not only increase the ultimate temperature rise, but also increase the rate of temperature rise. Internal curing can obviously improve the cement hydration behavior compared with the concrete without internal curing. The improvements on cement hydration may present in two. One is the hydration rate in the second stage is increased; another is the final cement hydration degree is increased. For internally cured concrete, the water used to calculate the water to binder ratio can be simply summing the mixing water and internal curing water together when calculate the final cement hydration degree. The proposed cement hydration rate model can well predict developing of cement hydration degree for both ordinarily and internally cured concretes.