Modeling Concrete at Early Age Using Per

The prediction of early age behavior of cementitious materials is critical for assessing crack risks associated with concrete. This study aims to model the mechanical characteristics and autogenous shrinkage of concrete during early hydration. A percolation-type approach is employed on a discretely generated microstructure, utilizing a forest fire algorithm to account for the binding role of hydrates. This methodology identifies a hydration threshold below which concrete rigidity is minimal. The evolution of elastic characteristics is derived through a homogenization method on the percolated microstructure. The model also integrates capillary pressure, resulting from the hydration reaction, which influences autogenous shrinkage. Biot's theory facilitates the computation of this shrinkage and its progression relative to the percolation threshold. The findings indicate that as hydration progresses, mechanical properties rapidly develop, with specific attention to the interplay between autogenous shrinkage and the rates of hydration and mechanical strength development. Thus, the results contribute to a better understanding of early age behavior in concrete, enabling more predictive models for mechanisms underlying crack formation in structural applications.