In July of 2018, Infrasense mobilized a two-man team to perform a ground-coupled GPR survey of the road surface on a stone arch bridge in Orange, CT. With the help of a traffic control unit and a local police officer, the condition survey was carried out during overnight hours with minimal disruption to traffic. The survey implemented a ground coupled 900-MHz antenna and SIR-4000 control unit manufactured by GSSI, Inc. of Nashua, NH. The antenna was maneuvered across the roadway surface of the bridge in a grid pattern and the data was taken back to the office for evaluation.
The survey implemented a ground coupled 900-MHz antenna and SIR-4000 control unit
The results included tabular results of the asphalt cover thickness, rebar depth, and bottom of concrete depth by lane. Eight cores were extracted by a coring team to compare chloride content with the GPR results, which were found to correlate reasonably well. A color-coded plan view condition plot of the bridge with the concrete deterioration results found by GPR and coring was provided in the final report.