An Experimental Study on the Effect of Migratory Corrosion Inhibitors on the Durability of Concrete

The durability of reinforced concrete remains a primary concern in aggressive service conditions, where chlorideinduced corrosion of the embedded steel governs the loss of structural service life. Migratory Corrosion Inhibitors (MCIs) offer an attractive route to mitigation because they diffuse through the pore network of hardened concrete and build a protective film on the reinforcement without altering normal construction practice. This work reports an experimental evaluation of four commercial migratory corrosion inhibitors, designated MCI-1 to MCI-4 and their influence on the durability of high-strength concrete. An M50 mix containing fly ash and alccofine as supplementary cementitious materials was adopted as the base matrix and the effect of each inhibitor on transport behaviour was assessed through the water permeability test conducted as per IS 516 (Part 2, Section 1) and the rapid chloride penetration test (RCPT) performed in accordance with ASTM C1202 at 28 days of curing. MCI-1 produced the lowest depth of water penetration, 7.33 mm, about 64% below the control, indicating a denser near-surface pore structure. The RCPT data revealed a different order, with MCI-4 returning the most consistently low charge passed, 1803 coulombs and therefore the strongest control over chloride ion movement. One-way analysis of variance confirmed that the differences among the mixes were statistically significant for both tests (p < 0.01) and a Fick's-second-law estimate translated the charge data into service-life differences of several years. These results show that the benefit of an MCI is tied to the transport mechanism that controls deterioration, so the inhibitor must be matched to the expected exposure rather than chosen on a single index.