Testing of concrete by laser ablation

• US 5,592,283 A
• Filed: 04/03/1995
• Issued: 01/07/1997
• Est. Priority Date: 04/03/1995
• Status: Expired due to Fees

• Current Assignee: Fluor Daniel Hanford, Inc. (Fluor Corporation)
• Original Assignee: Westinghouse Hanford Co. (Paramount Global (f/k/a ViacomCBS Inc.))
• Inventors: Becker, David L., Flesher, Dann J., Cannon, N. Scott, Beem, William L., Berry, Tommy C.
• Primary Examiner(s): EVANS, FANNIE L
• Application Number:
  US08/415,842
• Time in Patent Office: 645 Days
• Field of Search: 356/72, 356/317, 356/318, 73/19.08, 73/54.03, 73/803
• US Class Current: 356/72
• CPC Class Codes: G01N 21/1702 with opto-acoustic detection, e.g. for gases or analysing solids
• CPC Class Codes: G01N 21/714 Sample nebulisers for flame burners or plasma burners nebulizers per se B05B
• CPC Class Codes: G01N 2291/0232 Glass, ceramics, concrete or stone
• CPC Class Codes: G01N 29/2412 using the magnetostrictive properties of the material to be examined, e.g. electromagnetic acoustic transducers [EMAT]; investigating the presence of flaws using eddy currents G01N27/90, magnetostrictive transducers B06B1/08, measuring magnetostrictive properties G01R33/18
• CPC Class Codes: G01N 29/2418 using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics photoacoustic cells G01N21/1702; measuring characteristics of vibrations by using radiation-sensitive means G01H9/00; acousto-optical conversion techniques for short-range imaging G01S15/8965; sound-producing devices using laser bundle G10K15/046
• CPC Class Codes: G01N 33/383 Concrete or cement

Abstract

A method of testing concrete in a structure in situ, by: directing a succession of pulses of laser radiation at a point on the structure so that each pulse effects removal of a quantity of concrete and transfers energy to the concrete; detecting a characteristic of energy which has been transferred to the concrete; determining, separately from the detecting step, the total quantity of concrete removed by the succession of pulses; and calculating a property of the concrete on the basis of the detected energy characteristic and the determined total quantity of concrete removed.

Claims

1. A method of testing concrete in a structure in situ, comprising:

directing a succession of pulses of laser radiation at a point on the structure so that each pulse effects removal of a quantity of concrete and transfers energy to the concrete;

detecting a characteristic of energy which has been transferred to the concrete;

determining, separately from said detecting step, the total quantity of concrete removed by the succession of pulses; and

calculating a property of the concrete on the basis of the detected energy characteristic and the determined total quantity of concrete removed.

2. A method as defined in claim 1 wherein the laser radiation has an energy density and wavelength selected to transfer energy to the concrete in order to effect vaporization of a portion of the concrete and the step of determining comprises detecting radiation emitted by concrete which is vaporized by the laser radiation and performing spectral analysis on the detected radiation.

3. A method as defined in claim 2 wherein the property calculated in said calculating step is the strength of the concrete.

4. A method as defined in claim 2 wherein the property calculated in said calculating step is the physical state of the concrete.

5. A method as defined in claim 2 wherein the concrete contains cement, sand and aggregate, the cement containing finely ground solid material, the concrete having a solid material/sand volume ratio and one property calculated in said calculation step is the solid material/sand ratio.

6. A method as defined in claim 5 wherein a second property calculated in said calculating step is a characteristic of the aggregate.

7. A method as defined in claim 2 wherein the concrete contains cement, sand and aggregate, the cement containing finely ground solid material which has a chemical composition and one property calculated in said calculation step is the chemical composition of the finely ground solid material.

8. A method as defined in claim 7 wherein a second property calculated in said calculating step is a characteristic of the aggregate.

9. A method as defined in claim 2 wherein the concrete contains aggregate having a given size and dispersed throughout the concrete, and one property calculated in said calculating step is a characteristic of the aggregate.

10. A method as defined in claim 9 wherein the characteristic is the size of the aggregate.

11. A method as defined in claim 9 wherein the characteristic is the uniformity of dispersal of the aggregate throughout the concrete.

12. A method as defined in claim 1 wherein the energy transferred to the concrete has the form of acoustic waves.

13. A method as defined in claim 12 wherein the property is the physical state of the concrete.