3-DIMENSIONAL COMPUTER-SIMULATION OF PORTLAND-CEMENT HYDRATION AND MICROSTRUCTURE DEVELOPMENT

A three-dimensional computer model for the simulation of portland ceme nt hydration and microstructure development has been developed, Starti ng with a measured particle-size distribution and a set of scanning el ectron microscopy images, a three-dimensional representation of a ceme nt of interest is reconstructed, matching the phase volume fractions a nd surface-area fractions of the two-dimensional. images, A set of cel lular-automata rules is then applied to the starting microstructure to model the chemical reactions for all of the major phases during the e volving hydration process, The dissolution cycles used in the model ha ve been calibrated to real time using a single set of parameters for t rue cements at three different water-to-cement ratios, Based on this c alibration, there is excellent agreement between the model predictions and experimental measurements for degree of hydration, heat release, and chemical shrinkage, The degree-of-hydration predictions have been successfully applied to predicting the compressive strength developmen t of mortar cubes for the two cements. The effects of temperature have been examined by performing hydration experiments at 15 degrees, 25 d egrees, and 35 degrees C and applying a maturity-type relationship to determine a single degree of hydration-equivalent time curve that can be compared to the model predictions, Finally, the computer model has been further extended to simulate hydration under sealed conditions, w here self-desiccation limits the achievable hydration.