A variety of applications of a three-dimensional digital-image-based computer model to studying cement hydration and properties has been demonstrated. The model provides a deeper understanding of the effects of physical microstructure and environmental variables on properties. As new and more detailed information becomes available on the basic mechanisms of cement hydration, the model will be concurrently updated to remove some of the assumptions currently being employed. As the model continues to be developed, it will provide a basis for examining new cement-based materials and optimizing formulations for a specific desired set of physical properties. Current research is focused on extending the model to incorporate pozzolanic materials; the incorporation of silica fume has been successfully completed [37] and that of fly ash is currently in progress [49]. Longer term efforts will focus on allowing compositional and molar volume variations in the C-S-H gel and incorporating an induction period mechanism into the model so that the very early time behavior of these complex materials may be better simulated.