Effects of Na2Cr2O7 Inhibitor on the Corrosion Potential Response of Steel Reinforced Concrete in Saline Medium

Electrochemical monitoring method of the open circuit potential was used to investigate the effect of the concentrations of Na2Cr2O7 on the corrosion potential response of steel reinforced concrete in sodium chloride medium. In the study, five different concentrations of Na2Cr2O7 admixtures were employed in a system of replicated samples of steel-reinforced concrete specimens partially immersed in 3.5% NaCl to simulate marine and saline environments. Forty days measured responses from these were subjected to the statistical analyses of the Normal and the Weibull distribution functions and tested using the Kolmogorov-Smirnov goodness of fit criteria. Results obtained from the analyses identified 4 g Na2Cr2O7 with optimal averaged potential response inhibition performance by the Normal model which showed better agreements in its models of Na2Cr2O7 potential test data than that obtained from the Weibull model of the same data. These bear pertinent implications on the need for suitability studies of appropriate statistical distribution for studying performance of corrosion inhibitors even as suggestions were proffered for addressing results conflicts among replicates of steel reinforced concrete samples employed

METHODS OF ASTM G16 AND CONFLICTS IN CORROSION TEST DATA: CASE STUDY OF NANO2 EFFECTIVENESS ON STEEL-REBAR CORROSION

In this paper, applications of the methods of ASTM G16 for addressing inherent conflicts in laboratory measurements of corrosion test data were studied, using the inhibiting effect of NaNO2 on the corrosion of concrete steel-rebar for the case study. For this, electrochemical monitoring techniques were employed for studying effectiveness of different concentrations of NaNO2 admixture in replicated concrete samples immersed in NaCl and in H2SO4 media for an experimental period of sixty-eight days. The corrosion test data from this experimental setup were subjected to the probability density fittings of the Normal and the Weibull functions as well as to significance testing methods of ASTM G16-99 R04 specifications. Results identified 10g (0.1208M) NaNO2 admixture with optimal inhibition efficiency model, η = 88.38±4.62%, in the saline/marine simulating environment and the 8 g (0.0966M) NaNO2 admixture with optimum effectiveness, η = 13.51±83.48%, in the acidic environment. The techniques of ASTM G16 adequately identified and addressed conflicting effectiveness from the test data of NaNO2 admixtures in the studied test environments