Methods for removing concrete decks from steel girder bridges
Brent M. Phares
Infrastructure in the U.S. transportation systems is at or beyond its current useful life (D'Agostino 2007), and many deteriorated concrete bridge decks need to be replaced. Removing these decks without damaging the bridge superstructure is a tedious and expensive task that often controls the deck replacement timeline. With ever tightening budgets and limitations of demolition equipment, states are looking for cost-effective, reliable, and sustainable methods for removing concrete decks from steel girder bridges. The goal of this research is to explore such methods. The research team conducted qualitative studies through a literature review, interviews, surveys, and workshops and performed small-scale trials and push-out tests (shear strength evaluations). Interviews with bridge owners and contractors indicated that concrete deck replacement was more economical than replacing an entire superstructure under the assumption that salvaged superstructures have adequate remaining service life and capacity. Surveys and workshops provided insight into advantages and disadvantages of deck removal methods, information that was used to guide testing. Small-scale trials explored three promising deck removal methods: hydrodemolition, chemical splitting, and peeling. Hydrodemolition is suitable for both partial and full-depth concrete removal, but containing and treating the water is expensive. Chemical splitting did not sufficiently break the reinforcing concrete. Peeling seems to be effective, but more testing is needed. Shear strength evaluations suggested that shear strength is not sensitive to the quantity of concrete removal and that it is not necessary to remove all of the concrete around shear connectors. Finally, a sustainability scorecard for bridge deck removal is proposed to incorporate sustainable practices into bridge deck replacement projects.