Full-depth precast deck panels with UHPC or grouted joints

How bridges get built · Precast concrete decks · Full-depth precast deck panels with UHPC or grouted joints

Also called: full-depth deck panels, precast deck panels, UHPC deck joints, FDDP

How it is done

Survey the girder tops and design the haunch and levelling for each panel (levelling bolts or shims); lay out the shear connectors in clusters at the pocket positions or along continuous channels.
Cast the panels in a plant with the edge detail of the chosen joint: female shear keys for grouted joints with longitudinal post-tensioning, or projecting lapped or headed bars for UHPC joints, and form the pockets or channels over the girders.
Prepare the girders: install or check the connectors at the pocket positions and fix haunch forms (foam strips or angles) along the girder edges.
Set the panels by crane on the levelling devices, adjust them to grade and line, and check joint widths.
Make the joints: either grout the transverse keys, stress the longitudinal tendons and then grout pockets and haunches, or place UHPC in the transverse and longitudinal joints and pockets and keep it covered while it cures.
Fill haunches and pockets completely with flowable grout or UHPC through vents, and check every vent.
Grind the surface for rideability (UHPC is placed slightly proud and ground flush), then seal or waterproof it and lay the overlay.

Key numbers

Panel thickness200–250 mm; length along the span about 2.4–3.7 m, usually the full deck width
Panel weightcommonly 10–30 t
Grouted-joint systemeffective longitudinal precompression of at least about 1.7 MPa (250 psi) across the transverse joints
UHPC jointsabout 150–250 mm wide; straight bars need only about 8–10 bar diameters of embedment in UHPC
UHPCcompressive strength generally above 150 MPa, with about 2 % steel fibres by volume
Connector clusterspockets at up to about 1.2 m spacing along the girder

Where it fits

Deck replacement on existing girders under night or weekend closures
New accelerated bridge construction projects and prefabricated bridge systems
Remote sites, short building seasons or cold climates where forming and curing a cast-in-place slab is slow

Where it does not

Girders with large or unpredictable camber differences, unless the haunch and levelling can absorb them
Heavily skewed, curved or warped decks where nearly every panel would differ
Contractors without UHPC or deck-grouting experience: joint and haunch quality decide durability

Choosing it

Choose it over a cast-in-place slab when closures are short (nights, weekends), for redecking under traffic, or where weather or remoteness makes forming and curing slow.
Choose UHPC joints over grouted keys with longitudinal post-tensioning for a near-monolithic, crack-resistant joint with short laps and no stressing; the post-tensioned system uses ordinary materials but adds stressing, anchor pockets and more steps in the closure.
Prefer cast in place when girder cambers are uncertain or variable, the deck geometry changes from panel to panel (heavy skew, curvature, warped surfaces) and time is not the constraint.
Prefer partial-depth panels when only the formwork time needs cutting and a cast-in-place topping is acceptable.

Plant, pace and money

PlantPrecast plant and transport, mobile crane, levelling hardware, high-shear UHPC mixers or grout pumps, post-tensioning jacks for grouted-joint systems, deck grinder.

ProductivityPanels for a span set in a day or two; grouting, joints and UHPC curing add a few days; redecking under traffic is done in nightly or weekend closures.

CostIndicative: USD 300–600 per m2 of deck in place, against USD 150–250 for a cast-in-place slab; UHPC joint material roughly USD 2,000–4,000 per m3. Shorter closures usually pay the difference on busy routes.

Risks and controls

What goes wrong

Leaking or cracked transverse joints, a historical weakness of grouted joints without enough longitudinal precompression
Voids in haunches and pockets that leave connectors unbonded
Panels rocking on uneven bearing before the haunch is grouted
UHPC leaking from joint forms, poor fibre distribution, or placing outside temperature limits
Poor rideability from levelling errors

Quality assurance

Full-size mock-up of a joint and pocket, UHPC flow and compressive tests, grout cube tests, level survey of the panels before grouting, vent checks for haunch fill, water ponding test of the joints, and a surface profile check after grinding.

Origins

Full-depth precast panels have been used for US deck replacement since at least the early 1980s, a well-known early case being the redecking of the original Woodrow Wilson Bridge (1983); field-cast UHPC connections came out of FHWA research and were first used on two New York State bridges in 2009.

Examples

Redecking of the original Woodrow Wilson Bridge near Washington DC with full-depth panels (1983); New York State's first field-cast UHPC deck-level connections (2009); a UHPC waffle-panel deck on a short-span bridge in Wapello County, Iowa (2011). The method is now common in US deck replacement and ABC programmes.

Case studies

Woodrow Wilson Bridge (original), Washington DC areaUSA · 1983Redecked with full-depth precast panels, an early large-scale use of the method on a heavily trafficked crossing.

New York State DOT UHPC connection bridgesUSA · 2009Two bridges in New York were the first to use field-cast UHPC for deck-level connections between precast elements, following FHWA research.

UHPC waffle-deck bridge, Wapello County, IowaUSA · 2011An 18 m bridge whose deck is made of precast UHPC waffle panels joined with field-cast UHPC and made composite with the girders.