Estimation of maximum temperature attained during concrete cure for internal sulfate reaction prevention in structures

Nowadays, delayed ettringite formation, DEF, still constitutes one of the main causes of concrete degradation in massive concrete elements or structures in Portugal. The most effective way to prevent the deleterious development of DEF is to control the maximum temperature attained during concrete cure. The tools currently available to practitioners, for predicting the maximum temperature attained in a concrete element, require the previous knowledge of the heat of hydration of the cement to be used in the structure. Several methods can be used to determine it, although the most common has been the Lagavant method, i.e. by means of semi-adiabatic calorimetry, the isothermal conduction calorimetry method is now becoming a widely used method. Since the two test methods produce different values, it is important to establish a correlation between the results obtained with both and to determine their influence on the temperature estimate made with the currently available calculation tools. The laboratory and in-situ tests reported in this paper allowed to gather a relevant amount of data pertaining to the heat of hydration of cement types normally used on massive structures or structures with massive elements, with the two abovementioned standardized methods; to establish a correlation on the heat of hydration values obtained with the two methods; and to use those heat of hydration values to perform estimates of the maximum temperature attained during concrete cure of a particular concrete mixture, used in a real structural element, which were very close to those measured experimentally on an experimental concrete viaduct deck section.