Coupled-multielectrode array technique to study chloride-induced corrosion at the steel-concrete interface

The necessity to reduce the risk of failure of reinforced concrete structures and to reduce the production of concrete, which is associated with a large formation of CO2, opened many questions concerning the material degradation mechanisms. The most dangerous mechanism of deterioration is represented by corrosion of steel in concrete, which leads to the reduction of the steel cross section over time and eventually to the failure of the structural element. The worst-case scenario is represented by chloride-induced corrosion which, although localized, normally causes the very fast loss of cross-section of the steel reinforcement. The output of this process is dangerous and well known, while many unanswered questions are still present in literature regarding the reactions and mechanisms leading to the initiation of chloride-induced corrosion with respect to the characteristics at the steel-concrete interface (SCI).

The project here proposed aims to analyze the location of the anodic and cathodic areas over time with respect to the presence of artificially created air voids at the SCI, in case of reinforced concrete exposed wet-dry cycles with a chloride-containing solution.

The project is experimental (i.e. performed in laboratory) and it will imply the use of the 3D printer (no preliminary knowledge required) to produce the casting molds, the concrete design and casting, the realization of arrays of steel electrodes, and to find a solution in order to realize an air void at the SCI (dimension range: ≈30μm-1mm) for each multi-electrode array. Finally, the corrosion current density circulating between the steel electrodes will be monitored to assess the electrode on which the anodic area is localized, with respect to the air void at the SCI, and its development over time (Hren et al., 2023).

The expected multi-electrode arrays specimens are shown in Fig.1.