Ground Penetrating Radar for Asphalt Concrete Density Profiling
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Date
2022-05-31
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Abstract
Ground penetrating radar (GPR) is a non-destructive, rapid, and continuous measurement tool that can predict density in asphalt concrete. Despite the promise of GPR as a quality assurance tool, the technology has been slow to adoption. Some of the hurdles include: GPR antenna stability and sensitivity; identifying the optimal air void content prediction model; understanding the sensitivity of dielectric to asphalt mixture variability; and lack of significant field deployment experience.
This research focused on a high-frequency (2.5 GHz), multi-channel, GPR system, which was designed specifically for the purpose of asphalt concrete density profiling. The stability of the GPR density profiler was thoroughly evaluated in the laboratory. The device was deployed to the field on several projects for multiple days of paving each. From these data the team compared the error and bias of two density prediction models. A laboratory study on mixture composition sensitivity was conducted. Finally, the density profile data from field projects was compared to traditional quality assurance testing from field cores.
The GPR density profiler has several advantages over traditional density test methods. Risks of incorrectly accepting or rejecting asphalt production, based on compaction, are dramatically reduced when using this equipment, as long as the calibration is unbiased. The empirical density prediction model, which had less error and less bias than the mechanistic model studied was recommended for use. Testing a standard reference material in the field each day may mitigate problems with bias. Recommendations were given for implementing the GPR density profiler in different construction and forensic settings.
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Keywords
Ground penetrating radar, asphalt concrete, dielectric, density, air void, quality assurance