Ground penetrating radar for scanning concrete girders Ultrasonic Tomography test on bridge deck
the subsurface medium. The reflected waves from subsurface
layers and objects are captured by the receiver antenna. The
scanning apparatus can be mounted on a truck or a special
vehicle and performs the scan at the traffic speed, which
eliminates the need for extended road closures. The main
advantage of GPR method is the speed of the test. The test
can provide a cost-effective and rapid tool for rapid screening
of bridge decks and identification of repair needs.10
Another application of GPR is to locate steel reinforcement
and prestressing tendons in concrete girders. This
becomes critical when signs of corrosion or other deterioration
mechanism is observed in the girder. GPR can also help
FEATURE
engineers identify the best location for taking cores from
concrete piers, girders and decks.
4. Ultrasonic Tomography
Ultrasonic Tomography methods use shear waves to determine
the thickness of concrete and to identify the location of
voids or defects. Tomography methods can help detect location
and depth of delamination and evaluate the integrity
of concrete.
The concept behind this method relies on the propagation
of stress waves through materials. An array of
transmitters introduces a stress pulse into concrete at an
Ultrasonic Tomography and impact-echo tests help identify the location of voids and delaminations
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