This research paper presents an analysis of the corrosion properties of steel-reinforced concrete samples during immersion in 3.5 wt. % NaCl aqueous solution by measuring their response both cathodic and anodic polarization in order to determine the corrosion rates in the function of their calcium nitrate inhibitor content. This cheap inorganic inhibitor was added to the concrete mix in concentrations of 1% and 3% by weight of cement in addition to two different superplasticizers (MapeiDynamon SR 31 and Oxydtron). The compressive strengths of the so prepared samples were also checked according to the relevant European standard and were within the acceptable limits, so this inhibitor does not weaken this important property of the concrete samples.
The test results on steel reinforced samples immersed in 3.5 wt. % NaCl aqueous solutions at room temperature showed promising corrosion mitigating effects just after 6 months testing period. After 6 months the lower corrosion currents (i.e. better corrosion resistance) for both types of superplasticizers were observed with those samples which contained 3% calcium nitrate inhibitor. The best result was observed with sample C4 (in this case 3% calcium nitrate was added to the mixture of cement+Oxydtron superplasticizer). The advantageous inhibition mechanism of nitrate anions is also discussed and interpreted.
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1. M.L. Rivetti, J.S. Andrade, N.S.Amorim and D.V. Ribeiro, Corrosion Inhibitors for Reinforced Concrete: Corrosion Inhibitors, Principles and Recent Applications, IntechOpen, 2017. http://dx.doi.org/10.5772/intechopen.72772
2. M. Adamu, L. E. Umoru, O.O. Ige, Effect of Calcium Nitrate and Sodium Nitrite on the Rebar Corrosion of Medium Carbon Steel in Seawater and Cassava Fluid. Journal of Minerals and Materials Characterization and Engineering2014, 2, 223-229. http://dx.doi.org/10.4236/jmmce.2014.23027
3. S. A. Abdulsada, É. Fazakas, T. I.Török, Corrosion testing on steel reinforced XD3 concrete samples prepared with a green inhibitor and two different superplasticizers, Materials and Corrosion2019, 70, 1262-1272. https://doi.org/10.1002/maco.201810695
4. S.A. Abbas, T.I. Török, É. Fazakas, Preliminary Corrosion Testing of Steel Rebar Samples in 3.5% NaCl Solution with and without a Green Inhibitor, Építőanyag – Journal of Silicate Based and Composite Materials2018, 70, 48-53. https://doi.org/10.14382/epitoanyag-jsbcm.2018.10
5. S.A. Abbas, É. Fazakas, T.I. Török, Corrosion studies of steel rebar samples in neutral sodium chloride solution also in presence of a bio-based (green) inhibitor, International Journal of Corrosion and Scale Inhibition, 2018, 7, 38-47. http://dx.doi.org/10.17675/2305-6894-2018-7-1-4
6. M.A.Quraishi, D.K.Nayak, R. Kumar and V. Kumar, Corrosion of Reinforced Steel in Concrete and Its Control: An overview, Journal of Steel Structures and Construction2017, 3, 1-6. https://doi:10.4172/2472-0437.1000124
7. S. A. Abdulsada, A.I. Al-Mosawi and A.A. Hadi, Studying the Effect of Eco-addition Inhibitors on Corrosion Resistance of Reinforced Concrete, Bioprocess Engineering2017, 1, 81-86. http://doi:10.11648/j.be.20170103.14
8. H. S. Ryu, S. H. Shin, C. G. Lim, T. W. Kang, S. Lim and H.T. Kim, Evaluation of Corrosion Resistance of Corrosion Inhibitors for Concrete Structures by Electrochemical Testing in Saturated Ca(OH)2 Solutions with NaCl and Na2SO4, Advances in Materials Science and Engineering2019, Article ID 8294360, 11 pages. https://doi.org/10.1155/2019/8294360
9. G.M. Akshatha, B.G. Jagadeesha and H. Pushpa, Effect of Corrosion Inhibitors in Reinforced Concrete, International Journal of Innovative Research in Science, Engineering and Technology2015, 4 (8), 6794-6801. https://doi.org/10.15680/IJIRSET.2015.0408013
10. Z. Marta, Effectiveness of Calcium Nitrate as Corrosion Inhibitor in Concrete, Master Thesis, Politecnico Di Milano, School of Industrial and Information Engineering, Department of Chemistry, Materials and Chemical Engineering, 2017.
11. EN 197-1, Cement – Part 1: Composition, specifications and conformity criteria for common cements, 2000.
12. EN 12620, Aggregates for Concrete, 2002.
13. H. Justnes, Concrete Corrosion Problems solved by Calcium Nitrate, in 25th Conference on Our World in Concrete and Structures, 349–356, 2000.
14. P. Saura, E. Zornoza, C. Andrade, and P. Garcés, Steel corrosion – inhibiting effect of sodium nitrate in simulated concrete pore solutions, Corrosion2011, 67, 075005-1-075005-15. https://doi.org/10.5006/1.3613642
15. C. Andrade and C. Alonso with contributions from J. Gulikers, R. Polder, R. Cigna, Ø. Vennesland, M. Salta, A. Raharinaivo and B. Elsener, Test methods for on-site corrosion rate measurement of steel reinforcement in concrete by means of the polarization resistance method, Materials and Structures2004, 37, 623-643. https://doi.org/10.1007/BF02483292