Résumé
Carbonation is one of the mains causes of reinforced concrete damage. It leads to decrease the pH of the concrete pore solution and to CaCO3 formation from the reaction between CO2 and cement hydrates. The mechanisms of carbonation are complex in low-clinker cementitious materials. At a given age, the hydration degree in low-clinker cementitious materials is reduced compared to CEM I materials which is due to the slower reaction of mineral additives and leads to the underdevelopped of microstructure. Therefore, the coupling between hydration, drying and carbonation at early age needs to be analysed, in order to understand and predict the durability of low-clinker cementitious materials. In this work, the coupled process leads to a faster drying of GGBS cement paste at early age compared to CEM I case. However, this trend changes when the GGBS reactions occur that are confirmed by the MIP results. Similar carbonation depth at early age are observed but a a lower carbonation degree suggests a lower difusivity and a finer microstructure for GGBS paste.