Research and Application of Compact Air-Coupled Ground Penetrating Radar in Thin-Layer Asphalt Thickness Testing and Vibration Resistant Calibration Method

• Published in: Transportation research record Vol. 2677; no. 5; pp. 777 - 792
• Main Authors: Xue, Lige, Zhao, Xun, Xu, Feiyun, Xu, Zhi
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01.05.2023
• Subjects: asphalt construction equipment: pavers; pavement condition evaluation; etc; rollers; ground-penetrating radar; measurement
• ISSN: 0361-1981; 2169-4052
• DOI: 10.1177/03611981221136133

For high-precision continuous thickness measurement of thin-layer asphalt loose paving, the paper proposes a compact ground penetrating radar (GPR) solution with smaller volume than the conventional air-coupled antenna. It takes into account the minimum identifiable thickness of the GPR tailing characteristics of radar signals, the common thickness range of thin-layer asphalt, and the vibration of construction machinery. In general, the overlap between bottom reflection and surface reflection of thin-layer asphalt can be solved by subtracting the reflection of the asphalt surface from the calibration waveform file of a metal plate. However, because the operating environment of asphalt paving is not suitable to realize the frequent static calibration of metal plates, the paper designs a bow-tie antenna loaded with high loss absorbent material substrate, which significantly improves the signal tailing phenomenon and greatly reduces the size of the air-coupled antenna. At the same time, in view of dynamic change of paver vibration and the requirements of the construction site, less calibration is more advantageous. Based on the full-amplitude reflection method, a fitting formula for the dielectric constant of asphalt suitable for mechanical vibration is proposed in this paper, to further improve the engineering applicability of the detection system. Finally, static calibration asphalt thickness, dynamic measured dielectric constant asphalt thickness, and manual sampling thickness under three construction conditions are compared, and the capability of the compact air-coupled GPR detection system proposed in this paper is comprehensively verified.