One of the key elements of pavement rehabilitation is knowing the pavement structure. A great companion to the FWD, the Ground Penetrating Radar (GPR) is a non-destructive testing device that is able to draw a detailed picture of what lies beneath the pavement surface.
The Ground Penetrating Radar (GPR) uses high frequency radio signals transmitting at regular intervals into the ground. When the wave hits a boundary between two different materials having different dielectric constants, the receiving antenna records variations in the reflected return signal, thus identifying pavement layers and buried objects.
We currently operate a high frequency 2 GHz horn- antenna and a 400 MHz ground-coupled antenna.
- GPR scans pavement in a continuous depth profile, enabling accurately locate pavement structure changes
- GPR provides valuable information for FWD strength analysis
- Based on GPR results, the destructive asphalt sampling, such as coring and drilling can be significantly reduced by selecting locations for intrusive testing where layer information should be confirmed
- GPR field survey is fast and safe, carried out within regular traffic
- GPR results can be plotted into Google Maps or GIS, since GPS coordinates is assigned for each scan location
Features of the RoadScan™30 System
- SIR-30, an advanced radar control unit capable of acquiring data from two antennas into one file during one pass
- Smart ID module air-coupled antenna with 2.0 GHz centre frequency allows data collection at highway speeds. Effective depth penetration of pavements is 0.5 – 0.75 m
- High-speed smart ID ground-coupled antenna with 400 MHz centre frequency allows data collection at speed up to 60 km per hour. Effective depth penetration on pavements is typically 2-3 m
- DMI and GPS data are linked to each radar signal
Typical use of GPR data:
- Pavement management – an efficient tool for quickly collecting inventory data
- Rehabilitation design – accurately identifying pavement thickness variation, transitions and modifications of existing structures
- Asphalt milling – insuring proper depth control for mill and fill rehabilitation and cold in-place recycling
- Construction of new pavements and overlays – GPR can provide a faster, non-destructive and more complete means of obtaining QA/QC data than coring
- Measuring asphalt layer thickness at each test point during FWD testing – FWD and GPR can be run in one operation
Collected GPR scans are processed using Radan7 software. Processed data can be displayed as radar images, or can be exported in the form of a text file. Radan7 can also generate KML files which can be downloaded to Google Earth with predetermined parameters (such as ranges of layer thickness).