Research civil engineer, Center for Building Technology, National Bureau of Standards, Gaithersburg, MD
The maturity method may be used to predict the in-place strength of hardening concrete based on its thermal history. A theoretical basis for the maturity method is presented. The general form of the time-temperature function is found to be the time integral of the rate constant. For the case of linear dependence between temperature and the rate constant, the time-temperature function becomes the traditional maturity function. The Arrhenius equation is shown to be an accurate representation of the temperature dependence of the rate constant, and the concept of equivalent age is explained for practical application of the Arrhenius equation. It is explained how the accuracy of strength prediction by the traditional maturity method can be improved by using the proper datum temperature. Results illustrate that the appropriate value of apparent activation energy or datum temperature for concrete may be obtained from strength-gain data of isothermally cured mortar specimens.
Paper ID: CCA10358J