Bridge deck evaluation with ground penetrating radar

Highway bridge decks must survive decades of repeated loading and environmental stress that can cause cracking, delamination, and corrosion. Efficiently maintaining and rehabilitating bridge decks requires accurate deck health assessments. Bridge deck inspection is often hampered by large portions of the damage occurring initially inside of deck and not appearing on the surface until it is at an advanced stage. Hence the need for non-destructive methods of evaluating the internal state of the deck. This paper describes the results of an ongoing study into the use of ground penetrating radar (GPR) for the inspection of bridge decks. GPR assumes that the interactions of electromagnetic waves with a material depends on the properties of the material. Spatial variations of the dielectric constants of the material will. cause reflected waves that can be measured. Analyzing the reflection of an electromagnetic wave can be used to assess the material properties of the deck. Key feature:; in the bridge deck that will affect GPR wave propagation are air and water voids, saturation, chloride ions, asphalt overlays, and rebars. This study is a multifaceted approach to the problem of using GPR for bridge deck inspection. Results of a numerical analysis of GPR interactions with bridge decks, laboratory studies of GPR, and antenna design, will be reported. The radar frequencies range from 0.5 to 6.0 GHz.