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Cracking in massive concrete structures due to temperature-induced stresses is a problem almost as old as concrete itself. Thermal gradients in bridge elements have historically been ignored in the U.S. As element size increases for structural, traffic, or aesthetic reasons, thermal gradients and thermal cracking have become serious concerns for bridge engineers. Accurate prediction of thermal gradients requires models that characterize the adiabatic temperature rise of concrete. The most common model for this purpose is the Arrhenius equation, which is widely used to characterize the temperature dependency of reaction rate. The Arrhenius equation uses activation energy (Eₐ) to define the sensitivity of a particular reaction to temperature. For portland cement, this constant is computed using either isothermal calorimeter data or mortar cube compressive strength. There is a large disparity in literature as to the proper method to determine Eₐ. This study examined twenty different cementitious pastes. Eₐ was computed for four of these mixtures using different computational methods. This study suggests a systematic computational method for characterizing Eₐ for any cementitious system. This work lays the groundwork for more extensive studies of a wider variety of cementitious systems |
