https://orcid.org/0000-0003-1794-5695
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ABSTRACT
Fusion-bonded-epoxy (FBE)-coated steel rebars have been used in many concrete structures in anticipation of better corrosion resistance. However, due to premature corrosion observed, FBE-coated rebars are banned in many parts of the world. On the other hand, such rebars with damaged coating are still used widely in some other parts of the world. This paper discusses the thickness, continuity, flexibility, and chemical composition of coating. Also, the performance indicators such as electrical resistance, UV-resistance, moisture resistance, and chloride diffusion coefficient of coating, and the chloride threshold of FBE-coated rebars are discussed. Laboratory tests adopted techniques (EIS, LA-ICP-MS, and EDX) on samples of coating peeled-off from coated rebars and specimens of coated steel rebars embedded in cement mortar, indicate that more comprehensive and stringent specifications are required to promote the use of quality epoxy materials, FBE-coated steel rebars, and construction practices are recommended.
Abbreviations
| %bwob | = | : % by weight of binder |
| Clc-s, Clth | = | : Critical chloride threshold of steel-coating interface |
| tcoating | = | : Coating thickness |
| Dcl, concrete | = | : Chloride diffusion coefficient of concrete |
| Dcl, coating | = | : Chloride diffusion coefficient of coating |
| EIS | = | : Electrochemical impedance spectroscopy |
| EEC | = | : Equivalent Electrical Circuit |
| FBE | = | : Fusion-Bonded-Epoxy |
| FBEC-ND | = | : FBE-coated steel rebars in as-received condition with no damage or degradation |
| FBEC-RSD | = | : FBE-coated steel rebars with repaired scratch damage |
| FBEC-SD | = | : FBE-coated steel rebars with scratch damage |
| FBEC-UV | = | : FBE-coated steel rebars after 10 days of exposure to UV rays |
| LA-ICP-MS | = | : Laser ablation inductively coupled plasma mass spectrometry |
| NMR | = | : Nuclear magnetic resonance |
| RC | = | : Reinforced concrete |
| RC | = | : Resistance of the coating |
| RP, C-S | = | : Polarization resistance of the coating-steel interface |
| RSD | = | : Repair scratch damage |
| SD | = | : Scratch damage |
| S-C | = | : Steel-Coating interface |
| SEM | = | : Scanning electron microscope |
| UC | = | : Uncoated |
| UV | = | : Ultraviolet |
Acknowlegements
The authors acknowledge the financial support (Project No. EMR/2016/003196) received from the Science and Engineering Research Board, Department of Science and Technology, and the partial financial support from the Ministry of Human Resource Development of the Government of India, and funding of the research project by Akzo Nobel. The authors also acknowledge assistance from the faculty, laboratory staff, and students in the Construction Materials Research Laboratory in the Department of Civil Engineering at the Indian Institute of Technology Madras, India, and the support from the Department of Chemistry in the Centre for Building Materials at the Technical University of Munich, Germany.
Data availability statement
The authors confirm that the data supporting the findings of this study are available within the article.
Disclosure statement
No potential conflict of interest was reported by the authors.
Additional information
Funding
Notes on contributors
Deepak K. Kamde
Deepak K. Kamde earned his B.Tech. degree in Civil Engineering from SRCOEM, Nagpur and M. Tech. degree in Structural Engineering from SVNIT Surat, Gujarat. In 2020, he earned a Ph.D. degree in Civil Engineering from IIT Madras. He is Project Officer at IITM, Chennai, India. His research interests include corrosion, durability, service life estimation, repair, and cathodic protection of concrete structures. Email: [email protected]
Marc Zintel
Marc Zintel holds a Diploma and Ph.D. degree in Civil Engineering from Technical University of Munich, Germany. He is Business Development Manager of Construction Products at Swiss Steel AG, Emmenbrücke, Switzerland. His research interests include durability of reinforced concrete structures, life cycle costs and corresponding sustainability approaches. Email: [email protected]
Sylvia Kessler
Sylvia Kessler holds a Diploma from RWTH Aachen University, Germany and Ph.D. degree in Civil Engineering from Technical University of Munich, Germany. She is a Full Professor of Engineering Materials and Building Preservation at Helmut-Schmidt-University / University of the Federal Armed Forces Hamburg, Germany. Her research interests include durability, service life prediction, non‑destructive testing and maintenance and repair of reinforced concrete structures. Email: [email protected]
Radhakrishna G. Pillai
Radhakrishna G. Pillai holds M.S. and Ph.D. degree in Civil Engineering from Texas A&M University, USA. He is an Associate Professor in the Department of Civil Engineering, Indian Institute of Technology Madras, India. His research interests include corrosion, durability and service life estimation of steel-cementitious systems, maintenance/repair, and cathodic protection of concrete structures. Email: [email protected]