Field Testing Of An Ultra High Performance Concrete Overlay PDF Download

Bridge decks are commonly rehabilitated using overlays depending on the cause of deck deterioration, available budget, and desired service life of the rehabilitated structure. One emerging solution for bridge deck rehabilitation is thin, bonded ultra-high performance concrete (UHPC) overlays. As an overlay material, UHPC can provide both structural strengthening and protection from ingress of contaminates using a 1-in (25 mm) to 2-in (51 mm) layer of material. The first U.S. deployment of UHPC as a bridge deck overlay was completed in May 2016 on a reinforced concrete slab bridge located in Brandon. A few months after installing the UHPC overlay, a field inspection of the bridge identified some locations along the deck where delamination may have occurred. To address this concern, a field study was conducted in November 2016 to evaluate the bond between the UHPC overlay and the substrate concrete bridge deck. Researchers from the Federal Highway Administration’s (FHWA) Turner-Fairbank Highway Research Center (TFHRC) synthesized photographic evidence, conducted a field inspection of the bridge deck surface using a chain drag, and conducted physical testing of the UHPC-concrete interface bond using the direct tension bond pull-off test. Tested samples were taken back to TFHRC and the UHPC-concrete interface subsequently analyzed using scanning electron microscopy (SEM). The pull-off test data indicated that the UHPC overlay and the existing concrete bridge deck was intact, which was confirmed by SEM analysis.