The Bridges and Structures Bureau at the Iowa Department of
Transportation is responsible for evaluating and maintaining the
primary bridge system. The bureau uses various testing procedures to evaluate
the condition of the structures. Nondestructive testing (NDT) is used to
evaluate the properties of a material without causing damage. Common NDT methods
may rely upon use of electromagnetic radiation, sound, and inherent properties
of materials to examine samples. NDT incorporates all the technology for
detection and measurement of significant properties, including discontinuities.
This provides the means by which structures may be inspected without disruption
or impairment of serviceability. NDT has become an increasingly vital factor in
the effective conduct of research and design and is a highly-valuable technique
that can save both money and time.
Iowa DOT is investigating the use of ground penetrating
radar (GPR), impact echo (IE), ultrasonics (UT), half-cell potential (HP),
electrical resistivity, and others for detecting various levels of deterioration
in bridge decks.