Correlation of microstructure, electrical properties and electrochemical phenomena in reinforced mortar. Breakdown to multi-phase interface structures. Part II: Pore network, electrical properties and electrochemical response

Since reinforced mortar is a multi-phase composite material at different levels of aggregation, a combination of techniques, namely electrochemical impedance spectroscopy (EIS) (for investigating the electrochemical phenomena on the steel reinforcement) and microstructure analysis (for qualifying and quantifying the composite bulk material), was used to provide insight into the macro- and micro-level interactions, involved in conditions of corrosion and cathodic protection for the here investigated reinforced mortar specimens. 120days of exposure to the relevant conditions of chloride-induced corrosion and impressed current cathodic protection (CP), it was found that the accumulation, volume expansion and propagation of corrosion products bring about significant structural alterations in the cement matrix. Further, the current flow involved in CP applications, along with the protection itself, contributes to additional changes in the bulk material. In this study, the elements of the equivalent electrical circuit from EIS measurements are discussed in correlation to the evolution of porosity, pore size distribution and pore interconnectivity of the bulk matrix, during corrosion and CP application. The results indicate that different parameters in the EIS modeling concept correspond well to specific interface microstructures. tcomes of this combination of techniques will possibly provide implications for computer simulation of the corrosion process and CP applications as well as modeling of concrete performance in aggressive environments.