Chloride-induced corrosion poses a substantial risk to reinforced concrete structures. The use of Recycled Concrete Aggregates (RCA) as a substitute for Natural Aggregates (NA) exacerbates durability concerns. Indeed, the adhesive mortar paste reduces the mechanical characteristics of concrete, whilst possibly altering its durability. However, Recycled Aggregates Concrete (RAC) presents a sustainable construction approach that reduces landfill waste and conserves natural resources. A comprehensive experimental investigation was undertaken on concretes composed of NA and RCA. Their inherent properties in terms of water transport and chloride ion ingress were assessed. A multiscale chemo-hydraulic model was created using the Finite Element Squared (FE \(^{2}\) ) method, and then verified and calibrated. The model’s constitutive equations use intrinsic properties obtained from experimental data. The results demonstrate the model’s accuracy in providing additional insight into chloride ingress in both saturated and unsaturated concrete. The research findings suggest that the durability of RAC may be comparable to that of NAC under specific mixture quality and environmental conditions. To evaluate this, a modelling application was carried out, which replicated actual conditions on a maritime lock wall.