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Computer simulations

In addition to the experimental studies, computer simulations were performed using the NIST cement paste microstructural model [14]. For each of the two cements, initial 3-D cement particle images were created for w/c=0.3 and w/c=0.4, and then "computationally hydrated" under saturated and sealed conditions. In the case of sealed (self-desiccating) conditions, the computer model creates empty pore space as the hydration occurs to account directly for the chemical shrinkage. A previous calibration of model cycles to real time [14] was then applied to create model degree of hydration vs. time curves to compare to the experimental counterparts. In addition, two-dimensional slices from the "fully hydrated" three-dimensional computer model microstructures were created to compare to the SEM images for the two curing conditions for Cement 115 with w/c=0.3.