ABSTRACT
Abstract A digital-image-based microstructural model is applied to simulating cement paste-aggregate interfacial zone microstructural development in a variety of concretes. A starting model system consists of a single square, flat plate, or cubic aggregate surrounded by circular or spherical cement and mineral admixture particles. A cement hydration model based on a cyclic process of dissolution, diffusion, and reaction is utilized to hydrate starting microstructures. In addition to supporting the well known wall effect, the model has suggested that a "one-sided growth" effect also contributes to the microstructural features developed in interfacial zones. The effects of mineral admixture particle size and reactivity and those of aggregate reactivity and water absorptivity on interfacial microstructure are explored via simulation. In many cases, it appears that improvements in the uniformity and density of the interfacial zone microstructure can be achieved by controlling these properties. Quantitative validation of the model is obtained by comparing model systems to ones prepared in the laboratory for concretes containing 0, 10, and 20% silica fume. Good agreement between the two systems is observed. Keywords: Aggregate, Cement Hydration, Clinker, Computer Modelling, Interfacial Zone, Microstructure, Mineral Admixture, Simulation.
