A Long-Term Experimental Study on Evaluating Corrosion Currents in Reinforced Concrete for Marine Structures

This study investigates the corrosion currents in four reinforced concrete mixes—SL (cement replacement of 50% slag), FA (cement replacement of 20% fly ash), T1 (cement replacement of 50% slag and 20% fly ash), and T2 (cement replacement of 20% fly ash and 8% silica fume)—using an electromigration method to accelerate chloride transport and initiate corrosion within weeks/months. The corrosion propagation was monitored over 1600 days using electrochemical techniques such as Linear Polarization Resistance (LPR), Electrochemical Impedance Spectroscopy (EIS), and Galvanostatic Pulse (GP) measurements. The study evaluated how the composition of the concrete mixes and reservoir length influenced corrosion, by testing both binary mixes (SL and FA) and ternary mixes (T1 and T2). The results show that the LPR readings, which uses prolonged polarization, generally produces higher corrosion current values than GP readings, offering a dynamic view of corrosion but greater variability. The binary mixes with slag (SL) or fly ash (FA) exhibit higher corrosion currents, while ternary mixes, especially those containing fly ash and silica fume (T2), show reduced corrosion currents, suggesting improved resistance. The larger reservoir length contributed to higher corrosion currents, highlighting the critical influence of exposure conditions, concrete mix composition, and measurement techniques in evaluating corrosion. This underscores the importance of considering these factors collectively when assessing the durability and long-term performance of concrete in corrosive environments.