Long-Term Corrosion Behavior of Reinforced Concrete: Impact of Supplementary Cementitious Materials and Reservoir Size under Accelerated Chloride Ingress

This study investigates the long-term corrosion behavior of reinforced concrete (RC) subjected to accelerated chloride ingress over approximately 1600 days, employing electrochemical methods such as linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), and galvanostatic pulse (GP) testing. Two concrete mixes (T1 and T2), incorporating distinct supplementary cementitious materials (SCMs), were evaluated to determine their performance in aggressive environments. Specimens with varying reservoir lengths were exposed to a 10% NaCl solution, with electromigration applied to accelerate chloride transport. Electrochemical assessments, including measurements of rebar potential, concrete solution resistance, corrosion current, and mass loss, were conducted to monitor the degradation of embedded steel. The findings revealed that smaller reservoirs (2.5 cm) significantly restricted chloride and moisture penetration, reducing corrosion, while larger reservoirs (10 cm) resulted in greater exposure and higher corrosion activity. Additionally, T1 mixes (cement replacement of 20% fly ash and 50% slag) showed higher corrosion currents and mass loss, whereas T2 mixes (cement replacement of 20% fly ash and 8% silica fume) demonstrated enhanced matrix densification, reduced permeability, and superior durability. These results underscore the importance of mix design and exposure conditions in mitigating corrosion, providing critical insights for improving the longevity of RC structures in aggressive environments.