Development, Characterization and Applications of a Non Proprietary Ultra High Performance Concrete for Highway Bridges

Ultra-high performance concrete (UHPC) is a new class of cementitious materials that have exceptional mechanical and durability characteristics. UHPC is commercially available. However, its cost for construction of highway structures is prohibitive. Based on an extensive testing program, a new family of non-proprietary UHPC materials with excellent characteristics in compression and tension, as well as exceptional resistance to freeze-thaw and chloride ion penetration were developed. The most cost effective of these deviates from traditional UHPC mixtures in that it uses a 50:50 mix of Portland Type I and Ground Granulated Blast-Furnace Slag (GGBS) as a binder, lacks any silica powder (inert filler) and requires no post-placement treatment. The use of GGBS improves the material’s ‘greenness’ making it a more sustainable cementitious product. Specifications for making the new UHPC were proposed. The developed UHPC blend was then used to conduct a comprehensive study on bond between UHPC and deformed steel bars to facilitate and enable future structural applications. Bond pull out tests showed the developed UHPC requires significantly reduced development lengths in order to attain steel bar yield compared to traditional concrete. Models to characterize the bond strength were proposed and a UHPC joint consisting of two pre-cast bridge deck elements was developed and tested at full scale. It was shown that a 6” (150 mm) joint made of the developed UHPC was sufficient to successfully transfer loading between the decks.