Effect of maize gluten meal extract as natural corrosion inhibitor on steel in mortar corroded by chloride

Abstract

In this work, we focus on the longterm inhibitive effect on steel corrosion in mortar contaminated by chloride. Especially, when chlorine salt is introduced with mixed water, maize gluten meal extract (MGME) can be preferentially adsorbed on steel during the process of cement setting and hardening, and what is its inhibition effect in mortar? So the influence of MGME on the corrosion rate and surface state of reinforcement was systematically analyzed by electrochemical method, FTIR, Raman and SEM-EDS. During the early cement hydration process, MGME already expelled chloride ions from preferentially adsorbed on steel surface to form a protective layer, which effectively maintained the passivation state even corroded in 3 wt.% NaCl solution for 17 months. Steel surface characterizations further confirmed that MGME in mortar with 3 wt.% dosage could be adsorbed enough on steel surface to shield chloride attack and protect the integrity of FeOOH passive film. Inhibition efficiency of MGME is equivalent to the most commonly used and well-known effectiveness of inhibitors as nitrites and amines, can reach 92.74–97.86%. • MGME was innovatively used as natural inhibitor for reinforced concrete. • MGME could adsorb on steel in the fresh mortar within 2 h hydration time. • MGME expelled chloride ions from preferentially adsorbed on steel surface. • Its inhibition capacity equals to well-known effectiveness of nitrites and amines.