Embeddable corrosion monitoring-instrument for steel reinforced structures

• US 6,690,182 B2
• Filed: 07/06/2001
• Issued: 02/10/2004
• Est. Priority Date: 07/19/2000
• Status: Active Grant

• Current Assignee: Smart Structures, Inc.
• Original Assignee: Virginia Technologies, Inc.
• Inventors: Ross, Robert A., Hudson, Josef K., Jones, Stephen H., Kelly, Robert G.
• Primary Examiner(s): NGHIEM, MICHAEL P
• Application Number:
  US09/899,908
• Publication Number:
  US 20020057097A1
• Time in Patent Office: 949 Days
• Field of Search: 324/700, 324/699, 324/693, 324/71.2, 205/775.5, 702/34, 702/35
• US Class Current: 324/700
• CPC Class Codes: G01N 17/006 of metals
• CPC Class Codes: G01N 17/02 Electrochemical measuring systems for weathering, corrosion or corrosion-protection measurement
• CPC Class Codes: G01N 33/383 Concrete, cement

Abstract

A system for monitoring the material changes in a structure is disclosed through the use monitoring instruments embedded within the structure. The instruments have at least one sensor with electrodes in contact with the surrounding material and electronics that are contained within the instrument. The sensor signals are converted to digital and transmitted to an external data logger or computer for display of the digitized signals. The connection between the microcontroller and the data logger can be either through hardwire or RF. Power is provided to the electronic sensors through either external or local methods. A power management system can be used to place the electronics into a sleep mode when not in use. The electronics are encapsulated within potting material within an instrument case that is manufactured from a material having a flexural modulus equal to, or greater than, the surrounding material to prevent mechanical failure of the device before failure of the surrounding material. The case has protective trays to protect the electrodes and rounded adjacent connection lengths to prevent the case from developing cracks.

Claims

1. A system for monitoring the material changes in a structure using:

at least one monitoring instrument, each of said at least one monitoring instrument having a body, an individual ID and being embedded within said structure and having;

at least one electronic module, each of said at least one electronic module having sensors in contact with said material and electronic monitoring means within said monitoring instrument to receive signals from said sensor;

an analog to digital converter, said analog to digital converter receiving analog signals from each of said at least one electronic monitoring means;

a microcontroller, said microcontroller receiving signals from said analog to digital converter;

a digital to analog converter, said digital to analog converter converting signals from said microcontroller to each of said at least one electronic monitoring means; and

transmission means, said transmission means to transmit said digital signals to a data logger;

power means, said power means providing power to each of said at least one electronic module;

potting material, said potting material encompassing said modules within said monitoring instrument;

a data logger, said data logger being external from said structure and receiving and storing said digital signals;

wherein said monitoring instrument receives signals from said at least one electronic module, converts said signals from analog to digital and transmits said digital signals for each of said at least one monitoring based on said ID to said data logger.

2. The system of claim 1 wherein said data logger displays said digital signals.

3. The system of claim 2 wherein said data logger is a computer.

4. The system of claim 1 wherein said analog to digital converter amplifies and filters said signals, said amplification and filtration being programmable from said data logger.

5. The system of claim 1 further comprising a power management system, said power management system being in communication with each of said at least one electronic module, said analog to digital converter, said microcontroller, and said digital to analog converter, said power management system regulating power consumption by placing each of said at least one electronic module, said analog to digital converter, said microcontroller, and said digital to analog converter in a sleep mode when not in use.

6. The system of claim 1 wherein said material change is corrosion.

7. The system of claim 6 wherein one of said at least one electronic module measures conductivity.

8. The system of claim 6 wherein one of said at least one electronic module measures linear polarization resistance.

9. The system of claim 8 wherein said at least one electronic module has a steel working sensor and a stainless steel reference sensor to measure linear polarization, said steel working electrode having an exterior surface matching an exterior surface of structural reinforcement steel surrounding said monitoring instrument.

10. The system of claim 6 wherein one of said at least one electronic module is capable of measuring chloride concentration.

11. The system of claim 10 wherein said at least one electronic module has a Ag/AgCl chloride ion specific sensor and a MnO2 reference sensor, said voltage potential between said ion specific sensor and said MnO2 reference sensor indicating said chloride concentration.

12. The system of claim 1 wherein each of said at least one monitoring instrument is networked to, and communicates with, at least one other of said at least one monitoring instrument.

13. The system of claim 1 wherein said power means are external to said structure, said power means being hardwired to each of said at least one monitoring device.

14. The system of claim 1 wherein said monitoring device further comprises at least one local power means, said local power means generating power for each of said at least one electronic module.

15. The system of claim 14 wherein said local power means is at least one from the group comprising a piezoelectric generator;

an electrochemical galvanic couple; and

/or a RF power receiver using an impedance matching network.

16. The system of claim 1 wherein a first end of each of said sensors is on a first plane, thereby enabling said material changes to come in contact with each of said sensors about simultaneously.

17. The system of claim 1 wherein communication between said data logger receives said each of said at least one monitoring instrument is wireless.

18. The system of claim 17 wherein said wireless communication is RFID.

19. The system of claim 1 wherein said monitoring instrument is hardwired to said data logger.

20. The system of claim 1 wherein one of said at least one electronic module is a temperature module, said temperature module having temperature recording and transmitting means.

21. The method of monitoring corrosion in a steel reinforced concrete structure comprising the steps of:

assembling a monitoring device having electronic sensors having electrodes;

positioning said electronic sensors within a protective case to enable said electrodes to contact said concrete;

securing said electronic sensor within said protective case with a potting material;

placing at least one monitoring device within said concrete during construction, said monitoring device containing electronic sensors having electrodes to monitor said corrosion;

assigning each of said at least one monitoring device an ID number;

networking each of said at least one monitoring device with other of said at least one monitoring device;

connecting one of said at least one monitoring device to a data logger;

completing said concrete structure;

monitoring signals sent from said electronic sensors indicating corrosion levels within said structure at said data logger.

22. An instrument case to enable electronic sensors to be embedded into a structural material, said instrument case having:

a hollow body, said hollow body being manufactured from a material having a flexural modulus at least equal to said structural material stress divided to by said structural material strain and having a first end, a closed second end and multiple sides each of said multiple sides having a connection length with an adjacent side, said body being configured to contain and protect electronic modules from contact by said structural material;

at least one electrode receiving port in said first end, each of said at least one electrode receiving port enabling an electrode to contact said structural material;

at least one protective tray, each of said at least one protective tray extending from said first end at about a right angled to surround said at least one electrode receiving port;

at least one electronic sensor, said at least one electronic sensor being within said hollow body to receive data from said electrodes and transmit said data to a data gathering source;

at least one cable port to receive a network cable;

wherein said adjacent connection lengths are rounded to direct pressure from said structural material around said instrument case thereby preventing said instrument case from developing cracks from said pressure.

23. The instrument case of claim 22 further comprising attachment flanges, said attachment flanges being integral with said hollow body and tie receiving channels, thereby enabling said instrument case to be attached to reinforcement members within said structural material.

24. The instrument case of claim 22 further comprising at least one electrical sensor, each of said at least one electrical sensor having at least one external electrode and an internal electronic monitor means, said electronic monitoring means being within said instrument case and each of said at least one electrodes extending through said at least one electrode receiving port to place a first end of each of said at least one electrode in contact with said structural material and a second end of said electrode in electronic contact with said electronic monitoring means.