Craig Newston, Brad Weldon
Best practices; Bridge decks; Concrete bridges; Contraction; Overlays (Pavements); Skid resistance; Thermal expansion; Ultra high performance concrete
Overlays are placed on existing concrete bridge decks for reasons that include increasing cover for the deck reinforcing steel, improving rideability, and improving skid resistance. To increase service lives of bridge deck overlays, and subsequently the underlying concrete deck, this research project will investigate the possibility of using ultra-high performance concrete (UHPC) to overlay existing concrete bridge decks. UHPC has been shown to have exceptional durability and strength properties that have the potential to greatly improve the sustainability of overlaying concrete bridge decks by extending the service lives of both the overlay and the concrete deck. The research project consists of a comprehensive literature review to identify best practices for traditional overlay materials that might also be used for UHPC overlays and development of practices that will ensure a strong durable bond between the UHPC overlay and the substrate material. It is crucial that this bond is able to withstand stresses and deformation caused by shrinkage of the UHPC, thermal expansion and contraction of the deck and overlay, and movements caused by loads applied to the bridge. Laboratory experiments will be conducted to verify that the practices identified are effective at maintaining the bond between a UHPC overlay and existing concrete decks. The implementation phase of the project will entail documenting the best practices for UHPC overlay application to existing concrete decks in the form of design recommendations. Field implementation is expected in on a New Mexico Department of Transportation project in late 2018.