INSPECTION OF CABLES IN POST-TENSIONED BRIDGES

This paper describes some of the techniques currently available for inspecting the condition of tendons in post-tensioned bridges, and comments on their usefulness. The advantages and limitations of each technique are explained. Air flow testing checks the continuity of grouting within a tendon duct. In almost any survey, the grout inside a duct and the surrounding concrete will be tested for chloride levels. A half-cell is used to measure the electrical potential difference between the reinforcing steel and the concrete surface. In gamma radiography, a powerful source of gamma rays is used to produce two-dimensional radiographs throughout a structure. It is very expensive and requires massive shielding and safety precautions. In impulse radar, reflections are obtained from electrically contrasting layers, such as concrete/steel and concrete/air void. In an intrusive survey, the condition of the tendons can be inspected visually, after removing the surrounding concrete. In load testing, a large load is applied to the bridge, and the strain and deflection at key points are monitored. Pressure testing quantifies the size of voids within tendon ducts. In the author's experience, the most useful technique is to: (1) locate a tendon duct accurately, using impulse radar; (2) form a small diameter percussive hole using a blunt drill bit; (3) perform a pressure test; and (4) remove a 100mm diameter core to expose the duct.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/09670726
• Corporate Authors:

  PALLADIAN PUBLICATIONS LTD

  THE OLD FORGE
  ELSTEAD, SURREY  United Kingdom  GU8 6DD
• Authors:
  • STAIN, R T
  • Dixon, S
• Publication Date: 1919

Language

• English

Media Info

• Features: References;
• Pagination: p. 38-40
• Serial:
  • CONSTRUCTION REPAIR
  • Volume: 8
  • Issue Number: 1
  • Publisher: PALLADIAN PUBLICATIONS LTD
  • ISSN: 0967-0726

Subject/Index Terms

• TRT Terms: Bearing capacity; Bridge decks; Chlorides; Detection and identification; Detectors; Deterioration; Loss and damage; Posttensioning; Radar; Surveillance; X rays
• ITRD Terms: 3085: Bearing capacity; 3482: Bridge deck; 1614: Damage; 9115: Detection; 5255: Deterioration; 7314: Halide; 4789: Post tensioning; 6738: Radar; 9101: Surveillance; 6728: X ray
• Subject Areas: Bridges and other structures; Construction; Materials;

Filing Info

• Accession Number: 00665280
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• Files: ITRD
• Created Date: Sep 9 1994 12:00AM