In this work, we conducted an experimental and micromechanical investigation on the mechanical and chloride diffusion properties of recycled aggregates concrete (RAC). Due to the composite aspect of the recycled concrete aggregates (RCA), their impact on the properties of concretes is first evaluated by conducting an experimental campaign and further numerically modeled using micromechanical tools. Local mechanical properties of phases such as the attached mortar, the interfacial transition zones (ITZ) and the aggregates are also investigated by means of indentation tests at nano and microscale. Finally, experimentally informed multi scale model is established and the overall elastic modulus and chloride diffusion coefficient of concretes (with different rates of RCA) are computed and compared to experimental results at macroscopic scale for discussion. The established model provides a predictive tool for the mechanical and chloride diffusion properties of RAC.