Multiscale modelling of carbonation in concrete made with RCA

The objective of this work is to develop a carbonation model for concrete incorporating recycled concrete aggregates (RCA), with the aim of predicting and assessing the progression of carbonation. The broader goal is to evaluate the relative influence of key parameters on carbonation and, more importantly, to determine the overall impact of replacing natural aggregates with recycled ones. Understanding carbonation is essential, as it is a critical precursor to reinforcement corrosion-one of the primary degradation mechanisms in concrete structures. The numerical model has been developed based on various approaches from the literature. It was first implemented at a macroscopic scale, then extended to a multiscale framework to account for the intrinsic heterogeneity of concrete. This heterogeneity is represented through a representative volume element (RVE), which includes the mortar paste, aggregates, and the adherent mortar surrounding them. The model considers several coupled processes, as well as the chemical reactions resulting from the carbonation process within the concrete matrix. The implementation was carried out using the nonlinear finite element software Lagamine, developed at the University of Liège.