GPR Monitoring of Artificial Debonded Pavement Structures throughout Its Life Cycle during Accelerated Pavement Testing

Abstract

The paper gives an overview of a ground penetrating radar (GPR) experiment to survey debonding areas within pavement structure during accelerated pavement tests (APT) conducted on the university Gustave Eiffel’s fatigue carrousel. Thirteen artificial defect sections composed of three types of defects (Tack-free, Geotextile, and Sand-based) were embedded during the construction phase between the top and the base layers. The data were collected in two stages covering the entire life cycle of the pavement structure using four GPR systems: An air-coupled ultra-wideband GPR (SF-GPR), two wideband 2D ground coupled GPRs (a SIR-4000 with a 1.5 GHz antenna and a 2.6 GHz-StructureScan from GSSI manufacturer), and a wideband 3D GPR (from 3D-radar manufacturer). The first stage of the experiments took place in 2012–2013 and lasted up to 300 K loadings. During this stage, the pavement structure presented no clear degradation. The second stage of experiments was conducted in 2019 and continued until the pavement surface demonstrated a strong degradation, which was observed at 800 K loadings. At the end of the GPR experiments, several trenches were cut at various sections to get the ground truth of the pavement structure. Finally, the GPR data are processed using the conventional amplitude ratio test to study the evolution of the echoes coming from the debonded areas.

Comparison of Imaging Radar Configurations for Roadway Inspection and Characterization

“…The ratio values are calculated based on the angles (θ 1 , θ 2 ) corresponding to the maximum point inside the box. The estimated permittivity values of asphalt over the three zones, as indicated in Table 5, fall within the commonly encountered range for road asphalt [33][34][35] and are consistent with results reported in [27] over the same test circuit. The similar ε r 's of asphalt over the sand and air-gap zones are estimated from measurements acquired during the same sunny day, whereas over the geotextile zone, the measurement took place after a rain event, resulting in a high estimated permittivity value.…”

“…The peak of the geotextile response is not located at the actual interface depth of 8 cm due to the slower propagation of electromagnetic waves in the host medium. By taking the dielectric permittivity of asphalt, ε r ≈ 5, as reported in [27], into account, the depth axis can be scaled by √ ε r , shifting back the response of the layer to approximately 20 cm. The profiles measured in the C and X bands exhibit a comparable ratio between the reflectivities of the ground surface and of the defect layer.…”

PUMA Applied to Time Delay Estimation for Processing GPR Data over Debonded Pavement Structures

“…However, the simulation results suggested that the PUMA algorithm can be further enhanced in the case of fully correlated echoes, and this can be done by extending the PUMA algorithm to directly exploit the properties of the rank-deficient source covariance matrix. In the near future, it is planned to test PUMA on the existing field database in [43].…”

Plastic Roads in Asia: Current Implementations and Should It Be Considered?

“…Many standard tests empirically test the asphalt performance temporarily under controlled laboratory conditions that do not represent the real scenarios in the field [ 170 ]. Alternatively, accelerated pavement testing using Heavy Vehicle Simulator or Pavement Fatigue Carousel is currently being used to test the surface and structural changes of asphalt [ 171 , 172 ]. However, some parameters including gaseous emissions level when laying hot asphalt and the release of microplastics when plastic-modified roads are open to traffic due to abrasion exerted by vehicle tires cannot be assessed via accelerated pavement testing [ 164 ].…”