Corrosion Evaluation of Post-Tensioned Tendons– Case Studies

Corrosion and subsequent failure of post-tensioned tendons in concrete box girder bridges are more prevalent than expected. Typical corrosion investigations (such as visual, bore scope, impact echo, corrosion potentials, chloride contamination) may not identify on-going corrosion. It may actually provide a false sense of security while the tendons continue to corrode. There is a general belief that corrosion occurs only if there are voids in the grout. Based on our investigations, it is clear that tendon can corrode even if it is completely covered by grout. The corrosion tendency and the rate of corrosion of tendon primarily depend upon the quality of grout and the level of chloride contamination. At voids and at low pH grouts, corrosion can occur irrespective of chloride concentration. This article establishes the inadequacy of routine inspection methods used in the past. The rate of corrosion (along with other relevant factors) of the tendon is required to define the time-to criticality. The need for specific, targeted investigation to determine the overall condition of the structure is established. Based upon our field and laboratory corrosion investigations, the primary causes of tendon corrosion are compromised alkalinity of the grout and the presence of voids. However, the rate of corrosion can vary based on the quality of the grout, the availability of moisture, the level of chloride contamination or a combination of these factors. Therefore, it is important to measure the rate of corrosion along with other critical factors. The rates of corrosion of tendons will help in determining the time-to-criticality. This information will be useful to the owner in determining the remaining structural capacity and identifying areas that require strengthening.

  • Supplemental Notes:
    • The title of this paper is listed in the Table of Contents on the CD ROM as Corrosion Evaluation of Post-Tensioned Tendons in a Box Girder Bridge—Case Studies.
  • Corporate Authors:

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590

    National Concrete Bridge Council

    Portland Cement Association, 5420 Old Orchard Road
    Skokie, IL  United States  60077-1083

    Missouri Department of Transportation

    105 West Capitol Avenue
    Jefferson City, MO  United States  65102

    American Concrete Institute (ACI)

    38800 Country Club Drive
    Farmington Hills, MI  United States  48331
  • Authors:
    • Venugopalan, Sivaraman
  • Conference:
  • Publication Date: 2008

Language

  • English

Media Info

  • Media Type: CD-ROM
  • Features: Figures; Photos; References;
  • Pagination: 12p
  • Monograph Title: HPC: Safe, Affordable, and Efficient

Subject/Index Terms

Filing Info

  • Accession Number: 01105154
  • Record Type: Publication
  • Files: TRIS, USDOT, STATEDOT
  • Created Date: Jul 24 2008 1:42PM