Berger [10] has investigated the use of cement clinker aggregate in concrete. He attributed the increased strengths of these systems to an improved cement paste-aggregate bond. More recently, Yang et al. have experimentally addressed the issue of engineering an optimum aggregate for concrete, consisting of an inert core and a reactive surface layer [11]. To model cement clinker aggregate, the aggregate is assigned a phase identifier of C3 S so that it is eligible for dissolution and reaction just like the smaller cement particles. Due to its small surface-to-volume ratio, only a thin layer on the outer surface of the clinker aggregate will undergo significant hydration.