Field Implementation of Ultra-High-Performance Concrete in Bridge Rehabilitation Projects

Title: Field Implementation of Ultra-High-Performance Concrete in Bridge Rehabilitation Projects in Maricopa County Presented By: Barzin Mobasher, Arizona State University Description: Use of Ultra-high-performance concrete, (UHPC) in transportation infrastructure is a major breakthrough due to its excellent mechanical performance and enhanced durability in comparison to conventional concrete. UHPC is chosen for the increased load-carrying capacity, high ductility, and to enhance the corrosion, creep, fatigue, and cracking resistance of newly designed as well as to repair aging and deteriorating bridges. While bridge decks, girders, or other cast-in-place or precast components can be developed, UHPC innovations in bridge design have further advanced its use as the shear connectors, repair material, or as ductile and impact absorbent materials in parts of bridge components. We present the results of an ongoing project supported by MDOT (2022-2023) in the use of non-proprietary, sustainable UHPC mixtures that incorporate locally sourced cement replacement and filler materials. Using this approach, significant cost reduction (of the order of greater than 70% compared to proprietary mixtures) was achieved. The main aspects of a successful UHPC mixture design are dense particle packing to reduce the porosity in the binder phase, low water content, chemical synergy in the use of cement replacement materials, and the use of fiber reinforcement. Thus the strength, ductility, and durability of structural elements are significantly improved. The mix design developed at ASU was transferred to a trial stage of the mockup testing, and batching plans of large volumes for connection pours were developed. Training of the construction crew led to the competency of the workforce in implementing this new application. The first UHPC bridge project in the state of Arizona used the approved mix design in the reconstruction of Palo Verde Rd bridge in Buckeye, Arizona. Design tools to enable application of UHPC for full-scale structural elements were also developed. Material properties from mechanical testing were used to predict the structural response of UHPC connection pours.