Concrete Scanning with GPR at Parking Garage - Orlando, FL
We were recently called out to a huge parking garage where dozens of directional signs were to be anchored into the concrete. There were also directional signs to be anchored into many of the concrete columns. Prior to drilling, the customer had us scan every relevant surface to mark out all rebar, post tensioned cables, and conduits. Our findings were recorded with crayon and/or pencil on each surface so that they could be easily washed away once the project was complete. We created a 60 paged report that included graphics and descriptions of each location, along with a color-coded map that highlighted which spots were safe to drill, which required modifications, and which could not be scanned using GPR technology.
On this last point, there were some columns that were solid steel, and some that were covered with a metal sheath. GPR technology cannot scan metal surfaces, because the metal will return 100% of the GPR signal. GPR can find metal within a concrete slab precisely because the metal is so reflective of the radar signal. But if the entire surface is made of metal, the GPR signal all bounces back to the receiver at the first opportunity, and the data is useless. In the case of this parking garage, most of the columns were concrete, and thus could be scanned, but a few were solid metal. The floor surface was all concrete, and thus could be scanned in every location.
The image above illustrates the method of a GPR investigation.
The GPR antenna sends a conical radio signal into the concrete slab, in this case a 1600 MHz frequency. That radar signal penetrates the concrete until an obstructing metal reflects it back to the receiver. The GSSI computer is able to calculate the distance the signal has traveled in order to identify both the depth and the location of the relevant piece of metal. This method reveals all metal, including rebar, post tensioned cables, and conduits. Voids and PVC can also be located using GPR technology.
To order your GPR investigation, whether your project is small, big, or nationwide, call GPRS at 407.335.6588 or e-mail firstname.lastname@example.org