Determination of the Apparent Activation Energy of Concrete: Ea. Semi-Adiabatic tests of Heat Development

摘要

The method of equivalent age is one of the currently used non-destructive testing mehtods of concrete strength estiamtion. It is based on the Arrhenius' law, which has shown itself to be the most accurate in order to describe the influence of temperature on concrete strength development at early ages. A proper estimation is directly related to a correct determination of the Apparent Activation Energy : Ea. This is the unique parameter which characterizes the concrete mixture and which can be found in the Arrhenius' law. the major aim of this paper is to show how calorimetric tests under semiadiabatic conditions can be an alternative to unwieldy compressive tests procedures in order to determine Ea. The validity of the obtained Ea values has been verified by means of several mechanical tests. Moreover, the possibility of using iether mortar or concrete is partially dealt with. the water to cement ratio appears to naturally be considered as a constant in proportioning an equivalent mortar. Finally, the evolution of hte Apparent Activation Energy in relation to the degree of hydration is given .Hence, the widespread opinion that Ea depends on the degree of hydration is confirmed and a field of definition can be brought to the fore.