The obtained results by using isothermal calorimetric of activation energy Ea show the dependence of activation energy on water/solid ratio, and the rate of hydration process. The higher water/solid ratio, the lower the activation energy. The hydration reaction rate was occurred under three periods fast, long term as dormant and termination period. The hydration reaction is high with higher  water/solid ratio at lower hydration temperatures  25°C and 35°C.At higher temperatures (60°C and 80°C) the  density of hydration reduced with increasing water/solid ratio 0.7.The effect of temperature and water/solid ratio upon the heat of hydration reaction rate  was investigated and plotted