CORROSION EVALUATION OF POST-TENSIONED TENDONS ON THE MID BAY BRIDGE IN DESTIN, FLORIDA

An on-site inspection of corroded post-tensioning tendons and acquisition of samples from these tendons were performed upon the Mid Bay Bridge on January 4 and 5, 2001. The primary focus of the study was upon Tendon 2 of Span 40-A and Tendon 4 of Span 37-C, although other tendons were visually examined and subjected to some testing also. The inspection included and the subsequent analyses were based upon the following: (1) visual inspection, photographic documentation, and condition assessment of polyethylene ducts, grout, and tendons; (2) determination of electrical continuity between strands; (3) half-cell potential measurements in sound areas of grout; (4) pH measurements on exposed grout; (5) chloride analysis of grout samples; and (6) petrographic analysis of grout samples. The visual inspection revealed 1) corrosion of cables and individual wires thereof that ranged from minimal to severe, 2) presence of three broken wires, 3) evidence that duct grouting had not been performed according to specification, and 4) cracking of the polyethylene duct. The half-cell potential measurements indicated that there was no ongoing corrosion of cable exteriors at the time of the inspection for the locations upon the two tendons in question where the duct was removed. This was attributed to the grout having been dry and the relative humidity low. Active corrosion, as evidenced by presence of partially liquid, acidic reaction products, was observed upon previously exposed anchorage faces and cable ends. A mechanism for the duct cracking has been theorized. Left unaddressed, the cracks will eventually lead to enhanced corrosion because of facilitated moisture, oxygen, and chlorides access to the prestressing steel. Specific recommendations are made that include: (1) experimentation to confirm the deterioration mechanism and to better disclose the role of influential variables; (2) development of improved methods for nondestructive inspection and condition assessment of post-tensioning tendons; (3) "surgical" autopsy by corrosion professionals of subsequently disclosed distressed tendons; and (4) revision of construction and inspection specifications associated with post-tensioning tendons.

• 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

  Haydon Burns Building, 605 Suwanee Street
  Tallahassee, FL  United States  32301
• Authors:
  • Hartt, W H
  • Venugopalan, S
• Publication Date: 2002-4-15

Language

• English

Media Info

• Features: Appendices; Figures; Photos; References; Tables;
• Pagination: 56 p.

Subject/Index Terms

• TRT Terms: Chlorides; Condition surveys; Corrosion; Cracking; Ducts; Grout; Highway bridges; Inspection; Petrography; pH value; Posttensioning; Recommendations; Salt water areas; Tendons (Materials)
• Identifier Terms: Mid Bay Bridge (Destin, Florida)
• Uncontrolled Terms: Half-cell potential
• Geographic Terms: Destin (Florida)
• Subject Areas: Bridges and other structures; Design; Highways; Research; I24: Design of Bridges and Retaining Walls;

Filing Info

• Accession Number: 00924274
• Record Type: Publication
• Report/Paper Numbers: Final Report
• Files: TRIS, STATEDOT
• Created Date: May 29 2002 12:00AM