Effects of the Water-Cement Ratio and the Molding Temperature on the Hydration Heat of Cement

The effects of the water-cement ratio and the molding temperature on the hydration heat of cement were investigated with semi-adiabatic calorimetry. The specimens were prepared with water-cement ratios of 0.31, 0.38, and 0.45, and the molding temperature was specified at 10 and 20 degrees C. The experimental results show that, as the water-binder ratio increases, the value of the second temperature peak on the temperature curve of the cement paste decreases, and the age at which the peak appears is delayed. The higher the water-cement ratio, the higher the hydration heat release in the early period of cement hydration, but this trend reverses in the late period. There are intersection points of the total hydration heat curve of the cement pastes under the influence of the water-cement ratio, and this law can be observed at both molding temperatures. With the increase in the molding temperature, the age of the second temperature peak on the temperature curve of the cement paste will advance, but the temperature peak will decrease. The higher the molding temperature, the earlier the acceleration period of the cement hydration began, and the larger the hydration heat of the cement in the early stage, but the smaller the total heat in the late period. A subsection function calculation model of the hydration heat, which was based on the existing models, was proposed in order to predict the heat of the hydration of the concrete.