Corrosion Inhibition Performance of Rhizophora mangle L Bark-Extract on Concrete Steel-Reinforcement in Industrial/Microbial Simulating-Environment

In this paper, the corrosion inhibition performance of the bark-extract of Rhizophora mangle L admixture on steel-reinforcement in concrete, immersed in 0.5 M H2SO4 for simulating industrial/microbial environment, were studied. Different concentrations of the plant-extract were admixed in duplicated concrete samples immersed in the acidic test-solution and these were monitored using non-destructive electrochemical techniques, for seventy-five days experimental period. Statistical analyses of the corrosion test-responses, as per ASTM G16-95 R04, showed that the corrosion rate correlated with function of the admixed bark-extract concentration in concrete, the halfcell potential and the corrosion current from the corrosion test-setup. The experimental and predicted model, from the correlation, both identified 0.167% Rhizophora mangle L bark-extract (per weight of cement) with optimal effectiveness, n = 78.6% (experimental) or n = 70.7% (predicted) at inhibiting steel-reinforcement corrosion. The experimental model of inhibition efficiency compares well with results from literature, classifies as very good inhibition efficiency model and thus supports Rhizophora mangle L bark-extract as inhibitor of steel-reinforcement corrosion in industrial/microbial environment.