Anticorrosion and adsorption mechanism of rhizophora mangle L. leaf-extract on steel-reinforcement in 3.5% NaCl-immersed concrete

Abstract

This paper studies anticorrosion and adsorption mechanism of Rhizophora mangle L. leaf-extract on steel-reinforcement in concrete immersed in 3.5% NaCl test-environment. Open circuit potential, macrocell current and corrosion rate measurements were obtained from steel-reinforced concrete samples, into which different concentrations of the leaf-extract was admixed during casting, and which were immersed in the saline/marine simulating-environment. Corrosion noise resistance was modelled as the ratio of standard deviation of the corrosion potential to the standard deviation of the corrosion current. Analyses of these test-results showed that the corrosion rate from linear polarization resistance exhibited very good correlation with the noise resistance model for the leaf-extract concentrations studied. Further analyses identified Rhizophora mangle L. leaf-extract concentration with excellent corrosion inhibition efficiency performance on steel-reinforcement. Also data of anticorrosion performance followed the Langmuir adsorption isotherm model, which indicated physisorption as the prevalent corrosion-protection mechanism by the Rhizophora mangle L. leaf-extract on steel-rebar in concrete immersed in the 3.5% NaCl, simulating saline/marine environment.