Ground-penetrating radar (GPR) is a high-frequency electromagnetic method that GEOVision commonly for the NDE and NDT of bridge decks, asphalt pavements, concrete pavements, and other concrete structures. GPR is an ideal tool for conduit detection, pavement thickness measurements (concrete and asphalt), delamination surveys, conrete deterioration surveys, rebar mapping and rebar corrosion surveys.
GPR has been successfullyused to perform pavement inspections, at posted traffic speeds, on existing and new structures. Such surveys require vehicle-mounted air-coupled (horn) antennas, which deploy approximately 1.5 feet above the pavement surface; they also require the use of a high-speed data acquisition unit with an extremely clean signal. GEOVision employs the use of the best GPR equipment for highway applications, either a GSSI SIR-10B or a GSSI SIR-20 system with one or two 1.0 GHz Model 4108 antennas. Being the fastest data acquisition systems available, they can achieve survey results at higher speeds than any other GPR instruments, and either data acquisition unit can simultaneously operate one or two antennas (sensors).
Surveys can be performed with a single sensor along the centerline of a lane, with two sensors—one on each wheel-path, or with multiple passes so that complete lane coverage is obtained. Depending on the objective of the survey, a deployment methodology is designed to best obtain the desired information in an efficient and economic fashion. Some of the more common applications include measuring (a) overall thickness of asphalt (flexible) or concrete (rigid) pavement; (b) composite pavement overlay thickness (when asphalt is overlaid onto concrete pavement); or (c) the lateral extent of lane pavements (whether concrete or asphalt) prior to modification of shoulder pavement during a lane-widening operation
A couple of the more difficult pavement evaluation applications include (a) determining pavement condition, along with pavement substructure and (b) measurement of new asphalt pavement compaction as a Quality Assurance indicator. Typically, along with QA asphalt pavement compaction measurement, QA thickness is determined as part of the survey.
Pavement structure quality control and quality assurance:Asphalt air voide content
- Asphalt dialectric properties
- Base and subbase dialectric and relative
- Moisture content
- Pavement and base layer thickness
GEOVision has the most advanced data acquisition unit, antennas and processing software available for these particular applications, as well as many others. When integrated as part of a Pavement Maintenance System (PMS), then used with Road Doctor® software along with IRI, rutting, FWD, video, GIS and other pavement quality inspection tools, high-speed pavement surveys provide valuable project-level information to pavement design engineers