Electrochemical Impedance Spectroscopy Investigation of Accelerated Erosion Mechanisms in Cement-Based Materials Under an Applied Electric Field

To address the issues of lengthy test cycles and singular evaluation methods for the durability of cement-based materials in sulfate environments, this study conducted accelerated sulfate erosion experiments on 3D-printed cement-based materials incorporating various supplementary cementitious materials, such as fly ash (FA), silica fume (SF), and metakaolin (MK), by applying a controlled external electric field. Electrochemical impedance spectroscopy (EIS) was employed to characterize the extent of material degradation. By regulating electric field intensity and sulfate solution conditions, and integrating multiple analytical techniques including electrochemical impedance spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TG), this research revealed that the applied electric field accelerates both cement hydration and sulfate-induced degradation through enhanced ion migration. Furthermore, the impedance response characterized by electrochemical impedance spectroscopy showed a positive correlation with macroscopic mechanical properties. Comparative evaluation of sulfate resistance among cement composite systems, FA–cement composites, SF–cement composites, and MK-cement composites indicated that cement-based material with 10% FA addition exhibited the strongest corrosion resistance. This study analyzes the changes in electrochemical impedance spectroscopy characteristic parameters before and after the application of an electric field, systematically elucidating the evolution of the material’s microstructure and the patterns of durability degradation. It provides key mechanisms for understanding the durability evolution of cement-based materials exposed to sulfate environments under electric-field assistance, and lays both experimental and theoretical foundations for developing methods to enhance durability.