Recycled concrete aggregate (RA) from pavement demolition was used to make concrete. Ten concrete mixtures with different replacement percentages of RA (coarse and fine) were made. The corrosion rate of steel and the electrical resistivity of concrete were determined on reinforced concrete specimens subjected to wetting-drying cycles (3.5% solution of NaCl). Corrosion rate was determined using the electrochemical technique of linear polarization resistance, while the electrical resistivity was measured by electrochemical impedance spectroscopy. The results show that the use of RA introduces more interfaces in concrete, which accelerates the steel corrosion process because the porosity increases and the electrical resistivity decreases. However, steel corrosion and the electrical resistivity in concrete are not significantly influenced by replacing a maximum 30% of coarse aggregate or 20% of fine aggregate with RA.

In this work, the transport equations of ionic species in concrete are studied. First, the equations at the porescale are considered, which are then averaged over a representative elementary volume. The so obtained transport equations at the macroscopic scale are thoroughly examined and each term is interpreted. Furthermore, it is shown that the tortuosity-connectivity does not slow the average speed of the ionic species down. The transport equations in the representative elementary volume are then compared with the equations obtained in an equivalent pore. Lastly, comparing Darcy’s law and the Hagen–Poiseuille equation in a cylindrical equivalent pore, the tortuosity-connectivity parameter is obtained for four different concretes. The proposed model provides very good results when compared with the experimentally obtained chloride profiles for two additional concretes.