Ground penetrating radar (GPR) is an NDE technique that operates by transmitting short pulses of electromagnetic energy into the pavement structure from an antenna. These pulses reflect off of subsurface layers and objects providing a record of the conditions and properties. Infrasense uses a GSSI vehicle-based GPR system for data collection, in-house proprietary software for data analysis, and provides results in formats compatible with CAD and ArcGIS. GPR has a number of benefits for pavement evaluation that an increasing number of DOTs are starting to take advantage of. Below are 5 of the key reasons DOTs are currently using GPR to evaluate pavements.
1. Provides continuous pavement structure information.
GPR can detect the bound and unbound layer thicknesses. The layers can be plotted continuously providing a comprehensive depiction of the pavement structure, which can facilitate a rehab design.
2. No lane closures required.
GPR pavement surveys are carried out at driving speeds, so no lane closures are required.
3. Integrates with FWD testing to provide pavement layer moduli and remaining life values
Pavement layer thicknesses provided at FWD test locations via GPS coordinate synchronization.
4. Detects subsurface voids and presence of relatively high moisture content
Voids and areas of relatively high moisture content can be quantified and mapped. The maps are used to direct localized confirmative tests and ultimately facilitate a rehab design.
5. QA of new HMA pavement
New HMA pavements can be surveyed with GPR to provide a comprehensive map of relative density. This map can be used to direct coring and nuclear/ nonnuclear gauge testing.