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UHPC Closure Joints in Pre-fabricated Bridge Deck Systems
Carin Roberts-Wollman and Tommy Cousins
Virginia Tech
$147,100
Background Statement
Full-depth precast, prestressed bridge deck systems are a rapidly constructed, durable alternative to cast-in-place
reinforced concrete bridge decks. The systems usually consist of panels between 7 in. and 10 in. thick,
approximately 10 ft long and as wide as the roadway (up to ~40 ft). The panels are precast and pretensioned in the
direction transverse to traffic. The panels are cast with block outs above the supporting girders to allow for shear
connectors to extend from the girders into the slab. The panel-to-panel connection is typically a female-female
keyed joint, which has routinely been filled with grout. Typically, the panels are post-tensioned longitudinally to
improve durability and structural performance. A new development in concrete technology and an alternative to
grouted joints is UHPC (Ultra High Performance Concrete). UHPC has been shown to improve workability, reduce
labor for installation, provide superior durability, and yield long term cost savings over traditional concretes and
grouts.
The system has many advantages over conventional cast-in-place concrete bridge decks. The panels are
very high quality, since concrete quality and fabrication tolerances are significantly better in a precasting yard than
in the field. The decks can be prestressed in both directions, which can make them stiffer under service loads and
more impervious to the ingress of corrosion inducing chlorides and water. Also the precast decks can be more
rapidly constructed than conventional decks, which will reduce construction time and user costs related to traffic
slow downs and detours. Combining these advantages with the improved durability of UHPC should provide an
excellent alternative to conventional bridge deck systems.
Objectives & Work Description
The project objective is to investigate the behavior of UHPC concrete in the closure pours in panel-to-panel
connections in the above described bridge deck system. Of critical importance is the behavior of a UHPC joint in
positive bending (which puts the joint in compression) and negative bending (tension in the joint) under cyclic
loadings and long-term effects. Full-depth deck panel systems simulating actual bridge conditions will be tested
under repeated loadings under positive and negative bending. The test panels will be compositely connected to the
supporting girders. Both longitudinally post-tensioned and mildly reinforced UHPC panel-to-panel joints will be
tested. Degradation of the joint over time will be measured during testing.
Why is your team best for this project?
This team is best for the project for the following reasons:
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Profs. Wollmann and Cousins have over 40 years of combined experience in bridge design, analysis and
structural testing, and have been working with UHPC for the past four years. At the Structural Engineering and
Materials Laboratory at Virginia Tech the specialized equipment needed for mixing and curing UHPC is inplace.
Profs. Wollmann and Cousins are presently co-advising a PhD student who is investigating the use of UPHC
panels as a replacement to cast-in-place reinforced concrete decks. This is investigation has both analytical and
experimental componenets.
Prof. Wollmann has particular expertise in the long-term behavior of concrete bridge structures.
Presently at Virginia Tech, Profs, Wollmann and Cousins are completing a multi-year project which will
culminate the year with the construction of a bridge containing full-depth prestressed concrete panels.