Title and Subtitle:
Development of GDOT Ultra-High Performance Concrete for Bridge Deck Closure Pours
Lead PI:
Lauren Stewart
Lead Affiliate:
Georgia Institute of Technology
Co Pi:
Lawrence Kahn (Georgia Institute of Technology); Kimberly Kurtis (Georgia Institute of Technology); Giovanni Loreto (Georgia Institute of Technology)
Abstract:
The use of precast prestressed girders with composite precast deck panels along with the use of precast prestressed deck bulb-T girders provide for more economical bridges because of their ability to utilize accelerated bridge construction techniques. The use of concrete deck panels and deck bulb-T systems require the use of closure pours between the units. Ductal™, a proprietary ultra-high performance concrete (UHPC), has been shown to provide an outstanding link between deck segments for closure pours as narrow as 6-in, but Ductal is expensive. This research develops a concrete based on locally available materials (GDOT-UHPC), which has a direct tensile strength greater than 750 psi and ductility and toughness under tensile loads such that the concrete can develop the tensile yield stress of #5 (⅝-in. diameter) reinforcing bars within a 5-in. embedment length. Minimizing the width of the closure between deck and bulb-T units provides further economies by greatly simplifying formwork and eliminating shoring. Testing assured not only the short development length of reinforcement but also ultimate strength capacity of transverse and longitudinal closure pours. Further, best practices for formwork, closure design, UHPC mixing and placement, and quality assessment are considered.
NTL Report: