Article

Journal of Central South University

, Volume 20, Issue 12, pp 3697-3714

First online:

Analysis of inhibition of concrete steel-rebar corrosion by Na2Cr2O7 concentrations: Implications for conflicting reports on inhibitor effectiveness

  • J. O. OkeniyiAffiliated withMechanical Engineering Department, Covenant University Email author 
  • , I. O. OladeleAffiliated withMechanical Engineering Department, Covenant University
  • , I. J. AmbroseAffiliated withMechanical Engineering Department, Covenant University
  • , S. O. OkpalaAffiliated withMechanical Engineering Department, Covenant University
  • , O. M. OmoniyiAffiliated withMechanical Engineering Department, Covenant University
  • , C. A. LotoAffiliated withMechanical Engineering Department, Covenant UniversityChemical, Metallurgical and Materials Engineering Department, Tshwane University of Technology
  • , A. P. I. PopoolaAffiliated withChemical, Metallurgical and Materials Engineering Department, Tshwane University of Technology

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Abstract

Corrosion test data were measured using non-destructive electrochemical techniques and analysed for studying inhibition effectiveness by different concentrations of Na2Cr2O7 on the corrosion of concrete steel-rebar in NaCl and in H2SO4 media. For these, specifications of ASTM G16-95 R04 were combined with the normal and the Gumbel probability density functions as model analytical methods for addressing issues of conflicting reports of inhibitor effectiveness that had generated concerns. Results show that reinforced concrete samples admixed with concentrations having 4 g (0.012 7 mol), 8 g (0.025 4 mol) and 6 g (0.019 1 mol) Na2Cr2O7 exhibited, in that order, high inhibition effectiveness, with respective efficiency, η, of (90.46±1.30)%, (88.41±2.24)% and (84.87±4.74)%, in the NaCl medium. These exhibit good agreements within replicates and statistical methods for the samples. Also, optimal inhibition effectiveness model in the H2SO4 medium was exhibited by 8 g (0.025 4 mol) Na2Cr2O7 concentration having η=(78.44±1.10)%. These bear implications for addressing conflicting test data in the study of effective inhibitors for mitigating steel-rebar corrosion in aggressive environments.

Key words

corrosion inhibitor effectiveness saline/marine and industrial/microbial environments concrete steel-rebar normal and Gumbel probability distribution functions Kolmogorov-Smirnov statistics tests of significance