Pavement material microwave density measurement methods and apparatuses
First Claim
1. A method of determining a property of a sample from a response thereof to a field, the method comprising:
- exciting a resonant device across a contiguous radio frequency band, the radio frequency band extending up to and including a microwave frequency range, so as to produce an electromagnetic field having at least a first microwave frequency resonance mode, the resonant device being configured to interact with a pavement material sample comprising one of a cohesive soil mixture and an asphalt mixture, wherein the exciting step is performed according to a skin depth property of the pavement material sample such that the resonant device interacts with the pavement material sample at a selected depth therein, the resonance device being excited at lower frequencies within the radio frequency band for a greater interaction depth and at higher frequencies within the radio frequency band for a lesser interaction depth with the pavement material sample;
comparing a first response of the resonant device to the interaction with the pavement material sample across the radio frequency band, to a second response of the resonant device to an interaction with a control sample across the radio frequency band, so as to determine a frequency response of the pavement material sample to the electromagnetic field across the radio frequency band; and
correlating the frequency response of the pavement material sample across the radio frequency band to a material property of the pavement material sample, the material property comprising one of a moisture content and a moisture-less density of the pavement material sample.
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Accused Products
Abstract
A method of obtaining a material property of a pavement material from a microwave field generally includes generating a microwave frequency electromagnetic field of a first mode about the pavement material. The frequency response of the pavement material in the electromagnetic field can be measured, such as by a network analyzer. The measurement of the frequency response permits correlating the frequency response to a material property of the pavement material sample, such as the density. A method of correcting for the roughness of a pavement material divides the pavement into a shallow layer and a deep layer. Two planar microwave circuits measure the permittivity of the shallow and deep layer. The permittivities are correlated to correct for roughness. An apparatus for obtaining the density of a pavement sample includes a microwave circuit and a network analyzer. The network analyzer measures the frequency response to determine the density of the pavement material.
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Citations
18 Claims
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1. A method of determining a property of a sample from a response thereof to a field, the method comprising:
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exciting a resonant device across a contiguous radio frequency band, the radio frequency band extending up to and including a microwave frequency range, so as to produce an electromagnetic field having at least a first microwave frequency resonance mode, the resonant device being configured to interact with a pavement material sample comprising one of a cohesive soil mixture and an asphalt mixture, wherein the exciting step is performed according to a skin depth property of the pavement material sample such that the resonant device interacts with the pavement material sample at a selected depth therein, the resonance device being excited at lower frequencies within the radio frequency band for a greater interaction depth and at higher frequencies within the radio frequency band for a lesser interaction depth with the pavement material sample; comparing a first response of the resonant device to the interaction with the pavement material sample across the radio frequency band, to a second response of the resonant device to an interaction with a control sample across the radio frequency band, so as to determine a frequency response of the pavement material sample to the electromagnetic field across the radio frequency band; and correlating the frequency response of the pavement material sample across the radio frequency band to a material property of the pavement material sample, the material property comprising one of a moisture content and a moisture-less density of the pavement material sample. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of determining a density of a sample engaged with a waveguide, the method comprising:
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exciting a resonant device across a contiguous radio frequency band, the radio frequency band extending up to and including a microwave frequency range, so as to produce an electromagnetic field, having at least a first microwave frequency resonance mode, configured to interact with a microwave waveguide and a pavement material engaged with the microwave waveguide, wherein the exciting step is performed according to a skin depth property of the pavement material sample such that the resonant device interacts with the pavement material sample at a selected depth therein, the resonance device being excited at lower frequencies within the radio frequency band for a greater interaction depth and at higher frequencies within the radio frequency band for a lesser interaction depth with the pavement material sample; comparing a first response of the resonant device to the interaction with the microwave waveguide, to a second response of the resonant device to an interaction with the pavement material sample engaged with the microwave waveguide, across the radio frequency band; determining a difference between the first and second responses of the resonant device to provide a frequency response of the pavement material sample to the electromagnetic field; and correlating the frequency response of the pavement material sample to the electromagnetic field across the radio frequency band to one of a moisture content and a moisture-less density of the pavement material sample. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method of obtaining a density of a pavement material with a planar microwave circuit, the method comprising:
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obtaining a calibration data set comprising a plurality of calibration frequency responses of the planar microwave circuit as a function of density of a calibration material; placing the planar microwave circuit over a layer of the pavement material; exciting the planar microwave circuit across a contiguous frequency band including a microwave frequency range, so as to produce an electromagnetic field of a first mode with the planar microwave circuit about the pavement material, wherein the first mode is selected such that the electromagnetic field'"'"'s electric fields are substantially parallel to a rough surface to minimize surface roughness effects, and wherein the exciting step is performed according to a skin depth property of the pavement material sample such that the electromagnetic field generated by the planar microwave circuit interacts with the pavement material sample at a selected depth therein, the planar microwave circuit being excited at lower frequencies within the frequency band for a greater interaction depth and at higher frequencies within the frequency band for a lesser interaction depth with the pavement material sample; measuring a sample frequency response of the pavement material; and correlating the sample frequency response to a density based on the calibration data set. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification