Service Life Prediction of Inhibitors and Concrete Surface Coatings in Concrete-Embedded Reinforcing Steel Corrosion Caused by Chloride

Inorganic corrosion inhibitors and surface coatings have a number of drawbacks, such as high costs, toxicity to the environment, poor degradation, and environmental pollution. Green plant-derived corrosion inhibitors are being investigated extensively as a potentially useful substitute for conventional toxicity inhibitors.

In this study, we have tried to employ Calotropis gigantea and Azadirachta indica as environmentally friendly inhibitors to improve the chloride-induced corrosion resistance of reinforcing steel in concrete. The inhibitor efficiency of environmentally friendly inhibitors has been compared with chemical inhibitors and surface coatings.

The half-cell method and the linear polarization resistance method have been used to investigate the corrosion inhibition properties of steel bars embedded in cylindrical concrete specimens with different types of green inhibitors, chemical inhibitors, and surface coatings.

The addition of Calotropis gigantea and Azadirachta indica leaf extracts to fresh concrete demonstrated a positive impact on corrosion resistance with control mixes. The efficiency of corrosion resistance increased with chemical inhibitors and surface coatings. Corrosion resistance has been found to be higher in concrete samples coated with surface coatings. From the results, surface coating has been found to exhibit the highest efficiency than the chemical and green inhibitors.

Overall, the study has demonstrated that, in cases of chloride contamination, surface coatings, particularly polyurethane ones, can provide protection against rebar corrosion. Organic inhibitors have shown promise as non-toxic, environmentally benign substitutes, despite their lower effectiveness.