About the research
A variety of techniques have been used to repair damaged bridge decks. They can range from grouting to seal surface cracks to partial/full depth patching to replacing partial/full bridge decks. While each of these techniques can increase service life, none has been proven to completely prevent deck deterioration nor do they increase longevity.
With its superior durability properties, the use of ultra-high performance concrete (UHPC) with fiber reinforcement in bridge decks have been explored in Iowa as a means to combat wide-ranging bridge deck deterioration problems. Given that solid UHPC slab deck is prohibitively expensive, use of a waffle deck was successfully demonstrated. By optimizing the waffle deck configuration, it was shown that the waffle deck concept can be used to reduce the volume of the required UHPC in bridge decks in comparison to solid bridge deck panels. To further reduce construction cost and broaden the application of UHPC, use of a thin UHPC layer as an overlay has been explored with an intention of preventing deck cracking, reducing fatigue damage, and minimizing penetration of moisture and chloride ion into the bridge deck.
In an upcoming overlay project on a primary bridge in Sheldon, Iowa, with deck surface area three times as big as that of the Mud Creek Bridge upgraded with UHPC overlay, WALO will use a modified paver for the first time to place a thin UHPC overlay on a bridge deck. The deck surface will also be prepared using hydrodemolotion. All of this work will be completed by WALO as a subcontractor to Cramer & Associates, Inc. The research includes charaterizing the behavior of machine-placed UHPC overlay and monitoring the performance of the bridge deck over 18 months. The collected results will be used to formulate recommendations for the broader use of UHPC bridge deck overlays in a cost efficient manner.