CATHODIC PROTECTION AND ENVIRONMENTAL CRACKING OF STEEL TENDONS IN PRESTRESSED CONCRETE. FINAL REPORT. SECOND ANNUAL REPORT

Corrosion of prestressing steel in concrete has become a major technological problem with regard to both highway and building structures. While cathodic protection is now recognized as an appropriate technique for mitigating corrosion of steel in concrete, the possibility of environmental cracking (hydrogen embrittlement) in the case of prestressing tendon has limited its use. This report presents results of a program where hydrogen embrittlement susceptibility of both notched and smooth prestressing wire was evaluated in a simulated concrete pore water solution by the constant extension rate testing (CERT) technique. Variables investigated were 1) the magnitude of cathodic polarization, 2) pH and chloride ion concentration and 3) time of cathodic precharging. It was concluded that cathodic polarization (item 1 above) is the most influential factor with the other variables exerting a more modest role. In this regard, a potential of -0.900 volts, SCE, has been identified as a polarization threshold below which tendon fracture load is significantly reduced. Because of this potential threshold it is concluded that conventional, constant current cathodic protection systems should not be utilized for prestressed concrete systems unless accompanied by a lower limit potential interrupt. For some of the test conditions investigated, a fracture load reduction of about 10% accompanied wire failure in tests at potentials positive to the -0.900v threshold. In view of the fact that tendons are stressed in service to approximately 70% of ultimate, this modest fracture load reduction could result in failure of a limited number of tendons even when cathodic protection is in the proper range.

• Supplemental Notes:
  • See also first annual report, TRIS 481038.
• Corporate Authors:

  Florida Atlantic University, Dania Beach

  Department of Ocean Engineering, 101 North Beach Road
  Dania Beach, FL  United States  33004

  Florida Department of Transportation

  P.O. Box 1029
  Gainesville, FL  United States  32602

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Hartt, W H
  • Chen, T Y
  • Narayanan, P K
• Publication Date: 1989-5-31

Media Info

• Features: Figures; References; Tables;
• Pagination: 55 p.

Subject/Index Terms

• TRT Terms: Cathodic protection; Embrittlement; Laboratory tests; Prestressed concrete; Steel; Strain (Mechanics)
• Uncontrolled Terms: Hydrogen embrittlement; Strain rate
• Old TRIS Terms: Steel tendons; Test results
• Subject Areas: Bridges and other structures; Design; Highways; I24: Design of Bridges and Retaining Walls;

Filing Info

• Accession Number: 00491922
• Record Type: Publication
• Report/Paper Numbers: CMM-FAU-88-03
• Contract Numbers: 0376
• Files: TRIS, USDOT, STATEDOT
• Created Date: Mar 31 1990 12:00AM