CORROSION DETECTION IN STRUCTURAL TENDONS

• US 20150097589A1
• Filed: 10/08/2014
• Published: 04/09/2015
• Est. Priority Date: 10/08/2013
• Status: Active Grant

• Current Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Original Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Inventors: Orazem, Mark E., Chen, Yu-Min, Alexander, Christopher
• Granted Patent: US 9,829,452 B2
• Time in Patent Office: Days
• US Class Current: 324/693
• CPC Class Codes: G01N 17/04 Corrosion probes
• CPC Class Codes: G01N 27/02 by investigating impedance

Abstract

Various examples are provided for corrosion detection in structural tendons. In one example, among others, a method includes injecting current through a portion of a tendon assembly including a tendon at least partially encased in grout, where the current is injected through the portion of the tendon assembly via contact points on a surface of the grout. A potential across the portion of the grout surface is measured and a condition of the tendon can be based at least in part upon the current and the potential. In another example, a system includes supply electrodes to inject current into grout surrounding a tendon via contact with a surface of the grout, sensor electrodes to measure a potential difference between the supply electrodes, and an impedance detection device to determine an impedance of the tendon based at least in part upon the injected current and the potential difference.

Claims

1. A method, comprising:

injecting current through a portion of a tendon assembly including a tendon at least partially encased in grout, the current injected through the portion of the tendon assembly via contact points on a surface of the grout;

measuring a potential across a portion of the grout surface between the contact points; and

determining a condition of the tendon based at least in part upon the current and the potential.

2. The method of claim 1, wherein the condition of the tendon is based at least in part upon an impedance corresponding to the current and the potential.

3. The method of claim 1, comprising injecting current through the portion of the tendon assembly at a plurality of frequencies;

and

measuring a plurality of potentials across the portion of the grout surface, each of the plurality of potentials corresponding to one of the plurality of frequencies.

4. The method of claim 3, wherein the condition of the tendon is based at least in part upon the current injected at the plurality of frequencies and the plurality of potentials.

5. The method of claim 1, further comprising:

applying supply electrodes to the contact points on the surface of the grout to inject the current through the portion of the tendon assembly; and

applying measurement electrodes to measurement points on the surface of the grout, the measurement points located between the contact points.

6. The method of claim 1, wherein the portion of the grout surface is centered between the contact points.

7. The method of claim 1, wherein the condition of the tendon is associated with a portion of the tendon located between the contact points.

8. The method of claim 1, further comprising:

injecting current through a second portion of a tendon assembly via contact points on the surface of the grout;

measuring a potential across a second portion of the grout surface between the contact points of the second portion; and

determining a condition of the tendon based at least in part upon the current and the potential associated with the second portion of the tendon assembly.

9. The method of claim 8, wherein part of the second portion overlaps part of the first portion of the tendon assembly.

10. A system, comprising:

supply electrodes configured to inject current into grout surrounding a tendon via contact with a surface of the grout;

sensor electrodes configured to measure a potential difference between the supply electrodes, the potential difference measured via contact with the surface of the grout; and

an impedance detection device configured to determine an impedance of the tendon based at least in part upon the injected current and the potential difference.

11. The system of claim 10, wherein the impedance detection device is configured to determine a condition of the tendon based at least in part upon the determined impedance.

12. The system of claim 10, further comprising a controllable power source configured to supply current at a plurality of frequencies via the supply electrodes.

13. The system of claim 12, wherein the impedance detection device is configured to determine a condition of the tendon based at least in part upon potential differences measured at the plurality of frequencies.

14. The system of claim 10, further comprising probes including the supply electrodes, the probes configured to extend through access openings to allow contact of the supply electrodes with the surface of the grout.

15. The system of claim 14, further comprising measurement probes including the sensor electrodes, the measurement probes configured to extend through access openings to allow contact of the sensor electrodes with the surface of the grout.

16. The system of claim 15, wherein the access openings extend through a structure surrounding the tendon and the grout.

17. The system of claim 16, wherein the structure is a span of a bridge.

18. The system of claim 10, wherein the impedance detection device comprises processing circuitry configured to determine a condition of the tendon based at least in part upon the determined impedance.

19. The system of claim 10, wherein the supply electrodes and the sensor electrodes are silver-silver chloride electrodes.

20. The system of claim 19, wherein the supply electrodes and sensor electrodes are coupled to the grout via a conductive adhesive.