Corrosion performance of mild steel and epoxy coated rebar in concrete under simulated harsh environment
International Journal of Building Pathology and Adaptation
Article publication date: 30 May 2019
Issue publication date: 5 September 2019
The purpose of this paper is to present the results of a two-year long study carried out in order to evaluate the corrosion performance of mild steel bare bars (BB) and epoxy-coated rebar (ECR) in concrete under a simulated harsh environment of chlorides.
The blocks are subjected to Southern Exposure testing. The electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) and Tafel plot are performed to measure the polarization resistance and corrosion current densities of these rebars. Knife-peel test was performed to assess the adhesion between epoxy and underlying steel after two years of exposure.
Mild steel BB showed a high corrosion current density of 1.24 µA/ cm2 in Tafel plots and a very low polarization resistance of 4.5 kΩ cm2 in LPR technique, whereas very high charge transfer resistance of 1672 and 1675 kΩ cm2 is observed on ECR and ECR with controlled damage (ECRCD), through EIS technique, respectively. EIS is observed to be a suitable tool to detect the defects in epoxy coatings. After two years of immersion in 3.89 percent NaCl− solution, the mild steel BB were severely corroded and a considerable weight loss was observed, whereas under heavy chloride attack, ECR showed no deterioration of epoxy coating and neither any corrosion of underlying steel. Results of this study show that the durability of reinforced concrete (RC) structures with respect to corrosion could be enhanced by using ECR, especially in harsh climatic conditions.
The corrosion performance of mild steel and ECR in concrete under a simulating splash zone environment is evaluated. EIS was used to evaluate the health of epoxy and corrosion state of underneath steel rebars. EIS was able to detect the defects in epoxy. The durability of RC structures could be enhanced in harsh climate regions by using ECR.
The funding for this research was provided by the National Priorities Research Program of the Qatar National Research Fund (a member of Qatar Foundation) under the award no. NPRP 7-410-2-169. Authors would also like to thank Qatar Metals Coating Company (Q-Coat), Qatar Steel for providing the materials and support. The statements made herein are solely the responsibility of the authors and do not necessarily reflect the opinions of the Sponsor.
Sohail, M.G., Salih, M., Al Nuaimi, N. and Kahraman, R. (2019), "Corrosion performance of mild steel and epoxy coated rebar in concrete under simulated harsh environment", International Journal of Building Pathology and Adaptation, Vol. 37 No. 5, pp. 657-678. https://doi.org/10.1108/IJBPA-12-2018-0099
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