Electrochemical investigation of the influence of a durable exterior emulsion coating on the corrosion resistance of mild steel in simulated concrete pore solution

• N. Anitha¹, V. Velkannan², K. Kavipriya³, K. Bhuvaneswari¹, M. Lavanya¹, Gurmeet Singh⁴, Abdulhameed Al-Hashem⁵, S. Rajendran^1,6 and C. Lacnjevac⁷

¹ Department of Chemistry, Corrosion Research Centre, St. Antony’s College of Arts and Sciences for Women, Dindigul 62405, India
² Department of Chemistry, Thiagarajar College of Engineering, Thiruparankundram, Madurai Tamil Nadu, 625015, India
³ Department of Chemistry, PSNA College of Engineering and Technology (Autonomous), Dindigul, India
⁴ Vice Chancellor, Pondicherry University, Puducherry, 605014, India
⁵ Petroleum Research Centre, Kuwait Institute for Scientific Research, Ahmadi, Kuwait
⁶ Adjunct Professor, Centre for Nanoscience and Technology, Pondicherry University, Puducherry, 605014, India
⁷ Faculty of Agriculture, University of Belgrade, Nemanjina 6, Beograd 11080, Serbia

Abstract: In concrete technology, rebars are used to strengthen the structure of concrete. The corrosion resistance of mild steel rebars in simulated concrete pore solution has be evaluated by electrochemical studies such as polarization study and AC impedance spectroscopy. The mild steel rebars have been coated with Nippon paint, SUMO XTRA, Durable exterior emulsion. Corrosion parameters such as linear polarization resistance (LPR), corrosion current density, corrosion potential, Tafel slopes, charge transfer resistance (R_t), double layer capacitance (C_dl), phase angle and impedance value have been derived from electrochemical studies. In the presence of emulsion coating, it was observed that, LPR increases, corrosion current density decreases, R_t increases, C_dl decreases, phase angle increases and impedance value increases. When Durable exterior emulsion coated mild steel was immersed in simulated concrete pore solution, the LPR value increases from 283 Ohm·cm² to 1.37×105 Ohm·cm²; the corrosion current density decreases from 1.50×10^–4 A/cm² to 3.323×10^–7 A/cm²; charge transfer resistance increases from 50.25 Ohm·cm² to 64351 Ohm·cm²; double layer capacitance decreases from 1.01×10^–7 F/cm² to 7.93×10^–11 F/cm²; the impedance increases from 1.81 [log(Z/Ohm)] to 4.82 [log(Z/Ohm)] and the phase angle increases from 36.27° to 51.54°. These observations confirm that the emulsion coating is stable in the presence of simulated concrete pore solution. This has controlled the corrosion of the rebars in the concrete. There will be augment in the life time of the mild steel rebars. The corrosion inhibition efficiency calculated from electrochemical studies is greater than 99%.

Keywords: electrochemical investigation, emulsion coating, corrosion resistance, mild steel, simulated concrete pore solution, concrete technology

Int. J. Corros. Scale Inhib., 2023, 12, no. 2, 696-707
doi: 10.17675/2305-6894-2023-12-2-17

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