Ground Penetrating Radar Operation
The Ground Penetrating Radar (GPR) has a high frequency radio wave pulses to detect the echoes that return from within the material.
These discontinuities can be metallic and non-metallic pipes, conduit, sewers, post tension cables, cables, cable ducts, voids, foundations, reinforcing in concrete, cavities, transitions between soil and rock, filled areas, or buried objects.
This radar inspection can detect voids within concrete slabs and under concrete slabs, prior to concrete cutting, sawing, drilling, grinding, demolition and excavating, is a needed part in establishing a safe environment and is very cost effective.
When concrete is initially poured, it has a high free water content which causes both high attenuation and low velocity.
As curing occurs, hydration removes free water and locks it into the concrete structure resulting in an increase in velocity and a decrease in attenuation.
This latest technology can analyse concrete at depths up to 0.5 to 1 metre using 3D imaging. This system is user friendly and only requires one operator.
The GPR X-raying can conduct a concrete inspection of concrete block walls, concrete floors, concrete slabs, airport runways, tunnels, dams, and garages. Asphalt roads and surfaces can also be scanned.
Concrete X-ray Services uses a 1000 MHz Deep Penetration Concrete radar head, which is a high resolution antenna used for high quality radar measurements.
GPR utilizes different bandwidth antennas depending on the desired result of the survey being done.
Conquest in action!
The shallow layer of rebar appears in Figure 2, along with some of the 1” conduits between the rebar. Both the large diagonal conduits are shown in Figure 3. Figure 1 shows the site prior to concrete pouring. Rebar and conduits of different sizes and composition are embedded in the concrete.
Figures 2 and 3 show Conquest depth slices obtained several months after the concrete had cured. The shallow layer of rebar appears in Figure 2. Conduits are visible in the deeper slice in Figure 3. One inch diameter conduits are running left-to-right across the image; two of the conduits are directly underneath rebar. Larger diagonal-trending conduits are also visible.
By viewing multiple depth slices, Conquest enables users to locate the position and depth of any embedded features. Drilling and cutting can then be limited to the areas clear of rebar, conduits and other feature.