The use of Recycled Concrete Aggregates (RCA) in concrete provides a sustainable approach to limit the amount of Construction and Demolition Waste (CDW) that is landfilled, while preserving natural resources of aggregates. Recycled Aggregates Concrete (RAC)'s main challenge is its durability compared to Natural Aggregates Concrete (NAC). A significant risk to reinforced concrete structures is chloride infiltration, particularly in coastal or road environments. A multiscale chemo-hydraulic model has been created using the Finite Element Squared (FE²) method and has been verified and calibrated. The constitutive equations utilise intrinsic parameters derived from the experimental characteristics of concrete built in a laboratory. The model can replicate experiments with accuracy and provides a deeper insight into chloride ingress in both saturated and unsaturated concrete. The hysteresis phenomena present in the water retention curve of granular materials is studied experimentally and implemented numerically according to the Van Genuchten formulation. The impact on chloride ingress is analysed, where the degree of saturation is a crucial factor in the transport mechanism. The evidence indicates that under certain mixture quality and environmental conditions, the durability of RAC may be similar to that of NAC. To assess this, an application was conducted, which replicated a real-life scenario.