Investigation of Tack Coat Failure in Orthotropic Steel Bridge Deck Overlay

The failure of tack coat on orthotropic steel bridge decks is of concern because the loss of bonding ability between layers jeopardizes the deck overlay. This study investigated tack coat failure on an orthotropic steel bridge deck overlay. A field survey on overlay distress was first conducted on a regular double-layered epoxy asphalt concrete overlay to identify the major distresses. A follow-up survey was conducted by using infrared spectroscopy to detect the changes in chemical functional groups that may respond to distress. Contact analysis in a finite element platform was used to analyze the influence of the tack coat on the mechanistic characteristics of the deck overlay. Finally, shear clamps were used to evaluate the shear resistance performance of the tack coat. Comparisons of tack coat materials were made to support maintenance strategies for deck overlays.