Determination of apparent activation energy of concrete by isothermal calorimetry

摘要

In recent works at our laboratory, instrumentations have beendeveloped to carry out calorimetric tests on concrete in isothermal conditions,which give much information. The objective of this article is, on the basis of thistechnique, to study the validity of the Arrhenius law and to determine theevolution of apparent activation energy of the concrete. This parameter isnecessary for the calculation of the maturity of the concrete. Measurements ofhydration heat have been carried out for various conditions of isothermal curingand have allowed us to study the evolution of apparent activation energyaccording to the degree of hydration. Generally, activation energy is constant fora degree of hydration ranging between 5 and 50%. On the other hand, we haveobserved that this parameter varied with the temperature, which limits the use ofthis technique to thin elements.