Surface application of multifunctional compound to prevent and control combined chloride and carbonation corrosion in concrete

This paper presents the performance of a multifunctional generic compound, 4-Aminobenzoic acid (4ABA) as migratory inhibitor applied on hardened concrete surface to curb corrosion due to combined chloride and carbonated environment. Electrochemical techniques (LPR and EIS), gravimetric analysis were applied to evaluate the corrosion performance and the inhibition mechanism of 4ABA. Chloride and carbonation profiles were developed to investigate the dominant cause of corrosion during the exposure. Visual and microscopic analysis of concrete surface and rebar surface was also done. Compressive strength test was performed to study the effect of corrosion inhibitor on strength property of hardened concrete. Results confirm that 4ABA prolonged the passive state of rebar when used as preventive measure and restrained the on-going corrosion process when employed as repair strategy. Combined exposure by chlorides and CO2 leads to redistribution of chloride ions in concrete matrix. The results also conclude that during the combined exposure, chloride ions initiate the corrosion process and carbonation aggravates this process. Application of 4ABA does not influence the strength properties of concrete. ABA has performed the inhibition by protective layer development and shield formation against the negatively charged corrosive ions. Blended cement concrete system which was observed to be more vulnerable to corrosion was seen to attain similar corrosion resistance as OPC concrete after inhibitor application.