CORROSION EVALUATION OF EPOXY-COATED, METALLIC-CLAD AND SOLID METALLIC REINFORCING BARS IN CONCRETE

This report describes the work conducted from 1993 to 1998 to develop cost-effective "new breeds" of organic, inorganic, ceramic and metallic coatings, as well as metallic alloys that can be utilized on or as reinforcement for embedment in portland cement concrete. As part of the study, 12 different bar types were tested in concrete: black bars, 3 bendable and 3 nonbendable epoxies, Type 304 and Type 316 stainless steel, copper-clad, galvanized and spray metallic-clad reinforcing. Measurements of macrocell voltages, half-cell potentials, electrochemical impedance spectroscopy, linear polarization and mat-to-mat resistances were used in conjunction with visual observations to determine the effectiveness of each system. It was concluded that Type 316 stainless steel reinforcing bars should be considered at the design stage as a potential method for obtaining a 75- to 100-year design life. These bars had corrosion rates 800 times lower than that of the black bars, even when tested in precracked concrete. Costs associated with the bars limit their widespread use in concrete structures; however, for structures where repair to corrosion-induced damage is difficult, the additional costs associated with the stainless steel bars may be justified. Potential use includes marine substructures, tunnels, and bridges that carry significant traffic where costs associated with road closures are very high. The research supports the continued use of epoxy-coated reinforcing bars as a corrosion-protection system; as in all cases, the corrosion rates of the eopxy-coated bars were less than that observed for the black bars. However, when epoxy-coated bars are to be used, it is appropriate to: use epoxy-coated reinforcing for both top and bottom mats of slabs, minimize damage to the reinforcing bars during shipment and placement, and repair cracks in the concrete. Decks constructed using epoxy-coated bars on the top mat only are not expected to have the same durability as those constructed with two layers of epoxy-coated bars; however, even these structures will show improved durability compared with companion structures that used black bars alone.

• Record URL:
  https://ntlrepository.blob.core.windows.net/lib/21000/21800/21890/PB99146722.pdf
• 
• Corporate Authors:

  Wiss, Janney, Elstner Associates, Incorporated

  330 Pfingsten Road
  Northbrook, IL  United States  60062

  Federal Highway Administration

  Turner-Fairbank Highway Research Center, 6300 Georgetown Pike
  McLean, VA  United States  22101
• Authors:
  • McDonald, D B
  • Pfeifer, D W
  • Sherman, M R
• Publication Date: 1998-12

Language

• English

Media Info

• Features: Appendices; Figures; Photos; References; Tables;
• Pagination: 137 p.

Subject/Index Terms

• TRT Terms: Alloys; Copper; Corrosion resistance; Corrosion resistant steel; Costs; Epoxy coatings; Galvanizing; Metal coatings; Reinforced concrete; Reinforcing bars; Service life; Stainless steel
• Uncontrolled Terms: Electrochemical impedance spectroscopy; Half-cell potential; Macrocell voltage; Polarization resistance; Visual surveys
• Subject Areas: Design; Finance; Geotechnology; Highways; Materials; I34: Steels and Metals;

Filing Info

• Accession Number: 00760490
• Record Type: Publication
• Report/Paper Numbers: FHWA-RD-98-153,, Final Report,, 3D4d
• Contract Numbers: DTFH61-93-C-00027
• Files: NTL, TRIS, ATRI, USDOT
• Created Date: Mar 18 1999 12:00AM