Effects of organic corrosion inhibitors on the performance of repair mortars

Reinforced concrete (RC) structures are severely degraded due to the corrosion of the embedded reinforcing steel, and hence, the upgrading of RC structures is essential. Repairing mortar is widely used to improve durability and strengthen structures; however, further repairing might be required considering the extended life of the structure. The use of inhibitors to protect the reinforcement from corrosion has become of great interest. Therefore, it is vital to study the potential of using corrosion inhibitors in a newly repaired system. This study investigated the performance of a commercially available polymer-modified mortar with migrating and admixed corrosion inhibitors. The study examined repair mortar's fresh and mechanical properties with corrosion inhibitors using the workability, flexural strength, and compressive strength tests adopting submerged and sealed curing methods. The resistivity of reinforcement against corrosion was measured using the impressed current technique and mass loss test. The results revealed no adverse effect on the workability of repair material from the admixed corrosion inhibitor. The application of migrating corrosion inhibitor improved corrosion resistance by 29% with reduced mass loss; however, increasing the inhibitor dosage did not result in substantial changes under submerged and sealed curing conditions. On the other hand, the admixed corrosion inhibitor enhanced corrosion resistance by 15%, 28%, and 47% when the inhibitor dosage was at 0.5%, 1%, and 2%, respectively. This study proves that incorporating a corrosion inhibitor to the repair mortar in a repairing process can further delay the potential reinforcement corrosion.