A numerical model and associated calorimeter for predicting temperature profiles in mass concrete

摘要

This paper describes the development and operation of a finite difference heat model for predicting the time-based temperature profiles in mass concrete elements. The model represents a two-dimensional solution to the Fourier heat flow equation and runs on a commercially available spreadsheet package. An important problem facing heat modelling of concrete is that the rate of heat evolution at any point in the concrete element depends on concrete mixture parameters, time and position within the element. The present model resolves much of this complexity by using, as input, the results of a heat rate determination using a low-cost adiabatic calorimeter together with the Arrhenius maturity function to indicate the rate and extent of hydration at any time and position within the structure, based on the time-temperature history at that point. The paper presents a discussion of the structure of the finite difference model and its application to spreadsheet architecture. A brief description of the calorimeter is also presented together with the results of a verification exercise that was carried out to assess the accuracy of the model using a block of concrete instrumented with thermal probes. The results show that the model is able to predict the temperature at any point in the concrete block to within 2 deg C of the measured values.