Ground Penetrating Radar (GPR)
Ground Penetrating Radar (GPR) Explained – Ground-penetrating radar (GPR) is a non-invasive geophysical technique that uses radar pulses to create images of the subsurface. It's essentially a way to "see" what's hidden below the ground's surface without digging or disturbing the area. This technology transmits electromagnetic waves into the ground, which are then reflected back to the surface, allowing GPR to map and identify features like reinforcing bar within the slab, utilities, voids, or even buried objects.
What Does Ground Penetrating Radar (GPR) Detect
Buried Utilities
GPR is used extensively in utility locating. It can detect both metallic and non-metallic buried utilities, including gas lines, water mains, electrical conduit, telecommunications lines, and fibre optic cable. Unlike electromagnetic (EM) locating, which requires a conductive material to trace, GPR can find PVC and other non-metallic utilities by detecting the dielectric contrast between the pipe and surrounding soil.
Pipes
In addition to utility lines, GPR can locate pipes embedded in concrete slabs, walls, and columns. This is critical for concrete scanning applications, where coring, cutting, or anchoring into an unknown pipe can cause water damage, structural compromise, or injury. GPR identifies the location and depth of embedded pipes so work can proceed safely around them.
Buried Items
GPR has a long history of use in archaeology and forensic investigation. It can locate buried foundations, underground storage tanks (USTs), buried debris, and in some cases, unmarked graves.
Rebar and Structural Components
In concrete scanning, GPR locates rebar, wire mesh, post-tension cables, and other embedded structural elements. This is essential before any concrete penetration. Striking a post-tension cable releases the stored energy in the cable violently and can compromise the structural integrity of the slab. GPR identifies the location and depth of these elements so cores and cuts can be placed safely.