Electrical methods and systems for concrete testing
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.
1. 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 with a first probe to a first part of the concrete structure;
measuring with the electrical measurement system an output electrical signal with a second 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;
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 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 at least one of the output electrical signal and the low frequency electrical characteristic together with the plurality of relative locations and the global position.
2. 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;
inserting either the first probe into the fluid for applying the electrical pulse or inserting the second probe into the fluid for measuring the output electrical signal.
3. The method according to claim 1 , wherein
at least one of the first part of the concrete structure and the second part of the concrete structure is a reinforcing bar; and
the electrical measurement performed is the measurement of an electrical potential.
4. 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.
5. The method according to claim 1 , wherein
the low frequency electrical characteristic is a predetermined portion of the result of applying the predetermined signal processing algorithm to the output electrical signal.
6. The method according to claim 1 , further comprising
establishing a corrosion state of a reinforcement within the concrete structure in dependence upon the low frequency electrical characteristic.
7. The method according to claim 1 , further comprising
establishing a corrosion state of a reinforcement within the concrete structure in dependence upon at least the low frequency electrical characteristic and a second predetermined portion of the result of applying the predetermined signal processing algorithm to the output electrical signal.
8. The method according to claim 1 , wherein
the first part of the concrete structure is a reinforcing bar; and
the electrical pulse is applied via electromagnetic induction.
9. The method according to claim 1 , wherein
the electrical measurement system further comprises an inner pair of probes having a first predetermined spacing and an outer pair of probes having a second predetermined spacing, wherein
the electrical pulse is applied to the first part of the concrete structure via the outer pair of probes and the output electrical signal is measured with the inner pair of probes.
10. An electrical measurement system comprising:
a first probe for applying an electrical pulse to a first part of a concrete structure via a first probe;
a second probe for measuring an output electrical signal from 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;
at least one beacon of a plurality of beacons, each beacon including a predetermined portion of a transceiver providing pulses of a predetermined format;
a global positioning system to provide a global position;
a microprocessor for:
applying a predetermined signal processing algorithm to the measured output electrical signal to generate a low frequency electrical characteristic of the concrete structure;
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
a memory for storing at least one of the output electrical signal and the low frequency electrical characteristic electrical measurement together with the plurality of relative locations and the global position.
11. The electrical measurement system according to claim 10 , wherein
at least one of the first probe for applying the electrical pulse and the second probe for measuring the output electrical signal are to be inserted into a hole made within the concrete structure prior to performing the measurement, wherein
the at least one of the first probe and the second probe are electrically connected to the concrete structure via an electrically conductive fluid added to the hole and into which the at least one of the first probe and the second probe are inserted.
12. The electrical measurement system according to claim 10 , wherein:
the at least one of the first part of the concrete structure and the second another part of the concrete structure is a reinforcing bar; and
the electrical measurement performed is the measurement of an electrical potential.
13. The electrical measurement system according to claim 10 , 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.
14. The electrical measurement system according to claim 10 , wherein the low frequency electrical characteristic is a predetermined portion of the result of applying the predetermined signal processing algorithm to the output electrical signal.
15. The electrical measurement system according to claim 10 , further comprising establishing with at least one of a second processing circuit and a microprocessor a corrosion state of a reinforcement within the concrete structure in dependence upon the low frequency electrical characteristic.
16. The electrical measurement system according to claim 10 , further comprising establishing with at least one of a second processing circuit and a microprocessor a corrosion state of a reinforcement within the concrete structure in dependence upon at least the low frequency electrical characteristic and a second predetermined portion of the result of applying the predetermined signal processing algorithm to the output electrical signal.
17. The electrical measurement system according to claim 10 , wherein
the first part of the concrete structure is a reinforcing bar; and
the electrical pulse is applied via electromagnetic induction.
18. The electrical measurement system according to claim 10 , wherein
the first probe is an inner pair of probes having a first predetermined spacing;
the second probe is an outer pair of probes having a second predetermined spacing.