Nondestructive Testing for Concrete Bridges Using Residual Magnetic Flux Leakage Method

Detecting corrosion in post-tensioned concrete structures is of interest to many departments of transportation and bridge owners and has been the focus of numerous research studies. Several methods have been offered to detect corrosion in steel elements embedded in concrete. Among these techniques, magnetic flux leakage (MFL) is recognized to be an effective method for detecting corrosion. An investigation was conducted to develop the instrument and a strategy for detecting corrosion in major post-tensioned concrete bridges. Two methods were considered, active and residual. The residual MFL method differs from active MFL in that the area of interest is magnetized first and sensors are then used to map the residual magnetic field over the area of interest. Comprehending the meaning of the collected data formed a good portion of this study. After lengthy investigation it was concluded that the best approach for using MFL to detect corrosion was to use this technique for comparing the relative performance of various areas of the bridge and use the symmetry for making conclusions. This paper provides an overview of the approach used with an application to a major bridge that is in service. Although many factors, such as transverse bars over post-tensioning ducts, affect the signals obtained, the residual MFL method is judged to be an acceptable method to detect corrosion in strands and bars.

Language

  • English

Media Info

  • Media Type: CD-ROM
  • Features: Figures; Photos; References;
  • Monograph Title: TRB 86th Annual Meeting Compendium of Papers CD-ROM

Subject/Index Terms

Filing Info

  • Accession Number: 01045899
  • Record Type: Publication
  • Report/Paper Numbers: 07-3387
  • Files: TRIS, TRB
  • Created Date: Feb 8 2007 8:04PM