Bridge & Concrete Investigation
Concrete investigation requires high frequency GPRs. This is so that the wavelengths are sufficiently short to penetrate between any metal reinforcement. The degree of target definition depends on how the frequency is. This also means that the depth of penetration of the radar signals will be limited to some extent. As the area of interest is normally relatively close to the ground surface, this is not usually a problem.
Which Radar? Which Antenna?
Groundvue 3, particularly, the 1GHz, 1.5GH and 4GHz antennas are extremely useful. Figures 1 to 3 inclusive show examples of detection using these antennas on concrete and on bridge investigations. Groundvue 3 can be used as a single channel, a 4 channel multi-channel or an 8-channel multi-channel system It can be used on a trolley or vehicle mounted or hand towed depending on the area which needs to be investigated.
Both multi-channels collect data at traffic speeds because the antennas are simultaneously triggered, without cross channel interference. The data in Figure 3 was collected from a vehicle travelling at traffic speed and is from the 4GHz antenna.
Both systems are also extremely flexible and can be used in any antenna configuration or with any number of channels up to the system maximum.
Groundvue 5C, a single channel system with central operating frequency of 6GHz is also available for detecting near surface delamination. [Picture to be sourced].
Extras
Check out the crack detector head [Link to specialist tools] and also the automatic velocity transmission technique which can be done at traffic speeds also [Link to specialist tools].