ABSTRACT
There is an urgent need for effective, long-lasting rehabilitation solutions for deteriorated concrete bridge decks. Traditionally, deteriorated bridge decks are repaired using localized patches or thin, bonded overlays composed of conventional concrete (CC) materials. An alternative solution that is gaining popularity is ultra-high performance concrete (UHPC) overlays, in part due to superior mechanical and durability properties compared to CC. Bridge owners commonly ask about life cycle costs and environmental impacts of UHPC overlays. As such, this study evaluates and compares the environmental impacts of different bridge deck overlay technologies: CC, latex-modified concrete (LMC), and UHPC using life cycle assessment (LCA). The scope of the LCA is cradle-to-grave for a service life of 50 years. The analysis is conducted assuming the overlay technologies are deployed on a hypothetical, yet representative long-span, signature highway bridge structure. The major rehabilitation schedules are estimated based on the literature and communication with stakeholders. LCA results for cradle-to-built scope indicate that the UHPC overlay demonstrates comparable impacts to CC and LMC options in most impact categories. For the 50-year life cycle, UHPC overlay is the lowest-impact option, because of lower overlay thickness, less impacts of the existing bridge deck demolition and improved durability. The initial benefits of CC and LMC overlays are offset by the impacts of reconstruction. Unless a full 50-year service life is achieved by using CC and LMC overlays with no need for reconstruction, UHPC remains a favorable option from a life-cycle perspective.
