Pavement material microwave density measurement methods and apparatuses

Patent metadata

Field	Value
Publication number	US-11740187-B2
Application number	US-202117159647-A
Country	US
Kind code	B2
Filing date	Jan 27, 2021
Priority date	Oct 24, 2003
Publication date	Aug 29, 2023
Grant date	Aug 29, 2023

Abstract

Portable microwave material gauge for determining the quality of a pavement material is provided. The gauge includes an electromagnetic field generator configured to generate an electric field mode that penetrates into the material wherein the material includes a heterogeneous material including at least one of a pavement material and a soil material, a calibration data set, a sensor of size and shape to support the electric field mode and to determine the response of the pavement material to the electric field wherein determining the response includes determining a change in the permittivity as a function of a change in the quality of the material; and an analyzer configured to correlate the sensor permittivity response to the calibration data set wherein correlating the response includes using stored relationships between the material quality and the sensor response using calibration samples having changes in permittivity as a function of quality.

First claim

What is claimed is:

1. A portable material gauge for determining a quality property of a pavement material comprising:
an electromagnetic field generator configured to generate at least one frequency of an electric field mode that penetrates into a material, wherein the material includes a heterogeneous material including at least one of a pavement material and a soil material;
a memory storing a calibration data set represented by a frequency response relationship of known physical properties of a material, wherein the frequency response is stored in memory of the portable gauge;
at least one sensor operative of the electric field mode, wherein the at least one sensor is excited by the at least one frequency and determine a permittivity response of the pavement material to the electric field as a function of a quality property of the material; and
an analyzer configured to correlate the sensor permittivity response to the calibration data set wherein correlating the response includes using stored relationships between the material quality and the sensor response using calibration samples having changes in permittivity as a function of quality,
wherein the quality property of the pavement material is related to at least one of density, modulus, and moisture content,
wherein the frequency response is related to at least one of measured magnitude and phase of the sensor permittivity response as determined by the analyzer, and
wherein the electromagnetic field generator is configured to generate:
a single frequency at which the sensor permittivity response varies with compaction of the pavement material, or
a range of frequencies by sweeping across a bandwidth in which the sensor permittivity response varies with density of the pavement material,
wherein the at least one sensor comprise:
a first planar circuit sensor configured to measure a first permittivity in a sample volume corresponding to a first pavement material measurement, and
a second planar circuit sensor configured to measure a second permittivity in a sample volume corresponding to a second pavement material measurement,

wherein the analyzer is configured to determine at least one of a bulk and a surface permittivity of the pavement material by:
obtaining calibration data for the first and second planar circuit sensors by calibrating to a plurality of known pavement material permittivities; and
correlating the first permittivity and the second permittivity with the calibration data to determine the permittivity of the pavement material.

2. The portable gauge of claim 1 where the changes in permittivity are determined by a response of the at least one sensor incorporating impedance, admittance, loss, phase shift, scattering parameters, reflection, transmission, VSWR, phase velocity, and combinations thereof.

3. The portable gauge of claim 1 wherein the sensor response is of at least one or more frequency responses to characterize the quality property of the pavement material.

4. The portable gauge of claim 1 wherein the electromagnetic field generator is configured to generate a field having at least one of a resonant mode and a non-resonant mode.

5. The portable gauge of claim 1 wherein the electromagnetic field generator is configured to generate an electromagnetic field between 1 KHz and 10 GHz.

6. The portable gauge of claim 1 wherein the electromagnetic field generator is configured to generate an electromagnetic field of 1 GHz.

7. The portable gauge of claim 1 wherein the electromagnetic field generator is configured to generate an electromagnetic field of 2 GHz or 2.5 GHz.

8. A portable material gauge of claim 1 wherein the quality property is at least one of asphalt density and soil moisture.

9. A portable material gauge of claim 1 wherein the quality property is a modulus property of concrete or asphalt.

10. A portable material gauge of claim 1 wherein the analyzer is configured to correlate the changes in response to one of a volumetric property and a mechanistic property of the material.

11. The portable material gauge of claim 1 wherein the analyzer corrects for the quality property of the material based on measured material temperature.

12. The portable material gauge of claim 11 wherein the temperature correction is related to volumetric expansion of hot asphalt.

13. The portable material gauge of claim 11 wherein the analyzer is configured to determine a corrected relative density of the material, moisture content of the material, or quality property of a concrete material.

14. The portable material gauge of claim 1 wherein the at least one sensor further comprise at least one of a fringing field capacitor, a capacitance sensor, a leaky cavity sensor, a subsurface sensor, a surface sensor, and a monopole.

15. The portable material gauge of claim 1 , wherein the at least one sensor is operating as a multi mode device.

16. A method for determining a quality property of a pavement material comprising a portable gauge including:
generating an electromagnetic field producing at least one frequency of an electric field mode that penetrates into a material wherein the material includes a heterogeneous mix including at least one of a pavement material, an aggregate material, and a soil material;
incorporating a calibration data set represented by a frequency response relationship of known physical properties of a material, wherein the frequency response relationship is stored in memory of the portable gauge as at least one of an equation or table;
determining, using a first sensor of size and shape to support a first electric field mode that is excited by the at least one frequency, a first permittivity response of the pavement material to the electric field as a function of a quality property of the material;
determining, using a second sensor of size and shape to support a second electric field mode, be that is excited by the at least one frequency, and to determine a second permittivity response of the pavement material to the electric field as a function of a quality property of the material; and
correlating the sensor permittivity response to the calibration data set or relation wherein correlating the response includes using stored relationships between the material quality property and the sensor response using calibration samples having changes in permittivity as a function of quality,
wherein the response is related to at least one of measured magnitude and phase of the sensor permittivity response as determined by an analyzer,
wherein the electromagnetic field is generated:
at a single frequency at which the sensor permittivity response varies with compaction of the pavement material; or
across a range of frequencies by sweeping across a bandwidth in which the sensor permittivity response varies with density of the pavement material

wherein determining the permittivity response of the pavement material includes determining a permittivity of the pavement material by:
obtaining calibration data for the first and second sensors by calibrating to a plurality of known pavement material permittivities, and
correlating the first permittivity and the second permittivity with the calibration data to determine the permittivity of the pavement material.

17. A system comprising:
at least one portable electromagnetic sensor for determining a quality property of a pavement material based on a measurement by the at least one sensor and changes in permittivity determined by an impedance response of the sensors to the pavement material; and
an analyzer configured to corre

Assignees

• Troxler Electronic Lab Inc

Inventors

• Troxler Robert Ernest

Classifications

• G01N22/00 Primary

  Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more (G01N3/00 - G01N17/00, G01N24/00 take precedence) · CPC title

• G01N22/04

  Investigating moisture content · CPC title

• G01N33/38

  Concrete; Lime; Mortar; Gypsum; Bricks; Ceramics; Glass · CPC title

• G01N33/42

  Road-making materials (G01N33/38 takes precedence) · CPC title