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Incorporation of Fly Ash into a 3-D Cement
Hydration Microstructure Model
Extensions have been made to the NIST 3-D cement hydration and microstructure development model to incorporate pozzolanic materials such as silica fume and fly ash. These additions will enable the simulation of the hydration and microstructure development of blended cements as well as conventional Portland cements. SEM and image analysis techniques originally developed for differentiating the cement clinker phases present in a 2-D image of cement particles have been modified and applied to equivalent images of fly ash particles. Reactions have been proposed and the appropriate volume stoichiometries determined for the various components of fly ash. Some preliminary calibrations of reaction rate constants and dissolution rates have been performed by comparison to experimental results for the adiabatic heat signatures of a variety of concretes with various water-to-cement ratios and fly ash contents. Further research needed to complete this calibration is outlined.
Keywords: Building technology, cement hydration, computer modelling, fly ash, microstructure, pozzolan, silica fume, simulation.