One of the inherent advantages of a CA for modelling cement microstructure development based on digital images is its capability of handling complex particle shapes and chemical phase distributions. These features are much more difficult to capture in continuum−type models where particles generally must be described as simple geometric objects such as spheres or ellipsoids, as used by Struble et al (1989) . For digital image−based models, however, the complexity of the cement particles is limited only by the resolution of the underlying lattice. For the simulations described in this paper, the scale of the models is such that each site is about 1 µm on a side. While creating particles of essentially arbitrary complexity is relatively straightforward, generating particles which accurately represent an actual cement is a more formidable task. This section describes three methods we have used to create starting images.
3.1 Initial 2D Images Derived from Cement Micrographs