ELECTRICAL METHODS AND SYSTEMS FOR CONCRETE TESTING

• US 20140210494A1
• Filed: 01/30/2014
• Published: 07/31/2014
• Est. Priority Date: 01/30/2013
• Status: Active Grant

• Current Assignee: Giatec Scientific, Inc.
• Original Assignee: Giatec Scientific, Inc.
• Inventors: Ghods, Pouria, Alizadeh, Rouhollah, Salehi, Mustafa
• Granted Patent: US 9,638,652 B2
• Time in Patent Office: Days
• US Class Current: 324/700
• CPC Class Codes: G01L 1/10 by measuring variations of frequency of stressed vibrating elements, e.g. of stressed strings using resistance strain gauges G01L1/22
• CPC Class Codes: G01L 1/20 by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids of piezo-resistive materials G01L1/18; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
• CPC Class Codes: G01L 1/22 using resistance strain gauges
• CPC Class Codes: G01N 17/00 Investigating resistance of materials to the weather, to corrosion, or to light
• 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 17/04 Corrosion probes
• CPC Class Codes: G01N 27/02 by investigating impedance
• CPC Class Codes: G01N 27/026 Dielectric impedance spectroscopy electrochemical impedance spectroscopy for measuring corrosion G01N17/02
• CPC Class Codes: G01N 27/04 by investigating resistance
• CPC Class Codes: G01N 33/383 Concrete, cement
• CPC Class Codes: G01R 27/00 Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
• CPC Class Codes: Y02W 30/91 Use of waste materials as fillers for mortars or concrete

Abstract

Hundreds of thousands of concrete bridges and hundreds of billions of tons of concrete require characterization with time for corrosion. Accordingly, protocols for rapid testing and improved field characterization systems that automatically triangulate electrical resistivity and half-cell corrosion potential measurements would be beneficial allowing discrete/periodic mapping of a structure to be performed as well as addressing testing for asphalt covered concrete. Further, it is the low frequency impedance of rebar in concrete that correlates to corrosion state but these are normally time consuming vulnerable to noise. Hence, it would be beneficial to provide a means of making low frequency electrical resistivity measurements rapidly. Further, prior art techniques for electrical rebar measurements require electrical connection be made to the rebar which increases measurement complexity/disruption/repair/cost even when no corrosion is identified. Beneficially a method of determining the state of a rebar without electrical contact is taught.

Claims

1. A method comprising:

providing an electrical measurement system for measuring an electrical characteristic of a concrete structure;

providing at least one beacon of a plurality of beacons, each beacon including a predetermined portion of a transceiver providing pulses of a predetermined format;

providing a reference location for the at least one beacon;

performing an electrical measurement of the electrical characteristic of a concrete structure;

determining at least a relative location, the relative location being that of the electrical measurement system relative to a predetermined subset of the plurality of beacons; and

storing the electrical measurement together with relative location and the reference location.

2. The method according to claim 1, wherein

the reference location is determined using at least one of a global positioning system, triangulation, multilateration, surveying from a survey reference point, and a predetermined point on the concrete structure.

3. The method according to claim 1 further comprising;

providing a location determination system associated with at least one of the electrical measurement system and a predetermined beacon of the plurality of beacons, the location determination system employing at least one of a global positioning system, wireless based triangulation, and wireless based multilateration.

4. The method according to claim 1 further comprising;

repeating the electrical measurement of the electrical characteristic of a concrete structure for a plurality of locations of the electrical measurement system across a predetermined portion of the concrete structure;

automatically generating a contour map for the predetermined portion of the concrete structure using the plurality of electrical measurements in conjunction with the plurality of relative locations and the global position.

5. The method according to claim 1, wherein

before performing the measurement the following steps are also performed:

drilling a hole through the thickness of a covering to a layer of concrete forming a predetermined portion of a concrete structure;

filling the hole with a fluid which is electrically conductive;

connecting one end of an electrical measurement system for measuring an electrical characteristic of a concrete structure to the fluid and the other end to another part of the concrete structure.

6. The method according to claim 5, wherein

the another part of the concrete structure is a reinforcing bar;

and

the electrical measurement performed is the measurement of an electrical potential.

7. The method according to claim 1, wherein

storing the electrical measurement comprises transmitting the electrical measurement from the electrical measurement system to a microprocessor based device via a wireless interface operating according to a predetermined wireless standard and storing the electrical measurement within a memory of the device.

8. A method comprising;

providing an electrical measurement system for measuring an electrical characteristic of a concrete structure;

generating with the electrical measurement system an electrical pulse which is applied to a first part of the concrete structure;

measuring with the electrical measurement system an output electrical signal with a probe applied to a second part of the concrete structure, the output electrical signal being the result of application of the electrical pulse to the first part of the concrete structure;

applying a predetermined signal processing algorithm to the output electrical signal to generate a low frequency electrical characteristic of the concrete structure.

9. The method according to claim 8 further comprising;

providing at least one beacon of a plurality of beacons, each beacon including a predetermined portion of a transceiver providing pulses of a predetermined format; and

providing a global positioning system to provide a global position.

determining at least a relative location of a plurality of relative locations, each relative location being that of the electrical measurement system relative to a predetermined subset of the plurality of beacons; and

storing the electrical measurement together with the plurality of relative locations and the global position.

10. The method according to claim 8, wherein

before performing the measurement the following steps are also performed:

drilling a hole through the thickness of a covering to a layer of concrete forming a predetermined portion of a concrete structure;

filling the hole with a fluid which is electrically conductive;

connecting one end of an electrical measurement system for measuring an electrical characteristic of a concrete structure to the fluid and the other end to another part of the concrete structure.

11. The method according to claim 10, wherein

the another part of the concrete structure is a reinforcing bar;

and

the electrical measurement performed is the measurement of an electrical potential.

12. The method according to claim 9, wherein

storing the electrical measurement comprises transmitting the electrical measurement from the electrical measurement system to a microprocessor based device via a wireless interface operating according to a predetermined wireless standard and storing the electrical measurement within a memory of the device.

13. A method comprising;

providing an electrical measurement system for measuring an electrical characteristic of a predetermined portion of concrete structure, the electrical measurement system comprising at least four probes, the inner pair of probes having a first predetermined spacing and the outer pair of probes having a second predetermined spacing;

generating with the electrical measurement system a plurality of applied electrical currents which are applied to a first part of the concrete structure via the outer pair of probes, the plurality of applied electrical currents being at a series of predetermined frequencies from a predetermined lower frequency limit to a predetermined upper frequency limit;

measuring with the electrical measurement system a plurality of output electrical voltages with the inner pair of probes, each of the plurality of output electrical voltages being at one of the predetermined frequencies;

applying a predetermined signal processing algorithm to the plurality of output electrical voltages to generate a frequency dependent electrical characteristic of the predetermined portion of concrete structure; and

determining an indication of corrosion for the predetermined portion of concrete structure in dependence upon at least the frequency dependent electrical characteristic.

14. The method according to claim 13, wherein

the indication of corrosion is determined based upon the first derivative of the frequency dependent electrical characteristic.

15. The method according to claim 13 further comprising:

determining a measure of corrosion in dependence upon at least a derivative of the frequency dependent electrical characteristic.

16. The method according to claim 13, wherein

the steps of applying and determining are performed upon a microprocessor based device and the measurements from the electrical measurement system are transmitted to the device via a wireless interface operating according to a predetermined wireless standard.