Progress in in-situ electrochemical monitoring techniques for chloride ions in concrete structures

Chloride-induced corrosion of steel reinforcement is a major threat to the durability and safety of concrete structures. This review provides a comprehensive overview of the progress in electrochemical monitoring techniques for chloride ions in concrete, focusing on the development and application of Ag/AgCl ion-selective electrodes, all-solid-state chloride sensors, electrochemical impedance spectroscopy (EIS) sensors, and multiparametric analysis approaches. The fundamental principles, key advancements, and performance characteristics of each technique are discussed in detail. Ag/AgCl electrodes have shown excellent stability and reproducibility, with various preparation methods and microstructural optimizations enhancing their long-term performance. All-solid-state sensors offer improved durability and ease of integration, while EIS provides valuable insights into the corrosion mechanisms. Multiparametric analysis, combining measurements of chloride concentration, pH, and other parameters, enables a holistic assessment of the corrosion state. The review also highlights the challenges associated with sensor stability, selectivity, calibration, and integration with wireless sensor networks. Future perspectives emphasize the need for advanced materials, multifunctional sensor systems, IoT integration, machine learning, standardized protocols, and extensive field trials. By addressing these challenges and leveraging the potential of electrochemical monitoring techniques, effective corrosion management strategies can be developed to ensure the long-term integrity of concrete infrastructure.