Effect of Calculation Methods on Cement Paste and Mortar Apparent Activation Energy

Concrete hydration and strength development rates are a function of the concrete temperature, with higher temperatures leading to faster rates of reaction. The equivalent age maturity method is a commonly used method to model concrete property development under varying temperature curing conditions. The equivalent age maturity method requires the use of an activation energy value to account for the temperature sensitivity of the chemical reactions. Several experimental methods and calculation techniques are currently used to quantify the activation energy for concrete. This study compared the activation energy calculated using several different numerical methods from mortar strength, time of set, chemical shrinkage, and isothermal calorimetry paste and mortar experiments. The activation energy calculated from isothermal calorimetry experiments was found to be similar for paste and mortar. This indicates that aggregates have very little effect on the activation energy, which would permit the use of an activation energy calculated from cement paste to be used on concrete.