The Hawk Lake Bridge in Ontario, Canada incorporates innovative technology. It was built with ultra-high performance concrete (UHPC) in joints between the girders, in the approach slabs, and in the precast guardrail curbs. Designers chose glass fiber reinforced polymer (GFRP) reinforcing bars for all of its precast members. Precast box girders, precast approach slabs, and precast guardrail curbs were all used to speed construction. Also, it was the first time that field-cast UHPC was cured (in the field) at low ambient temperatures.
Lafarge's UHPC "Ductal®," also known as reactive powder concrete, was used for the project. The concrete provided a combination of superior properties including ductility, durability, and strength. This single-span bridge is 27.2 meters (89 ft-4 in.) long and 13.8 meters (45 ft-4 in.) wide. It includes 12 adjacent precast box girders with "Ductal®" joints connecting the girders. The decision was made to mix the UHPC joint material on site because of the remote location of the bridge. Because of the low ambient night-time temperatures during the project—0° to 15° C (32° to 59° F)—thermal blankets and heated water coils were used to ensure proper curing. Steel fibers were used in the self-leveling UHPC "Ductal®" joints. The average 28-day concrete compressive strength of the field-cured UPC joints was 145.2 MPa (21.0 ksi).
The bridge carries Trans-Canada Highway 17 traffic over the Canadian Pacific railway. It replaced a restricted-height underpass built in 1935, and now allows vehicles of any height to cross over top of the railway.
Owner: Ministry of Transportation of Ontario, Canada
Engineer: TPT Engineering
Contractor: Carillion Canada
Precast Concrete: Lafarge Construction Materials (Precast Division) Winnipeg. MB
Concrete Supplier: Lafarge North America
Ultra-High Performance Concrete Bridges
What is Ultra High Performance Concrete?
Ultra–high performance concrete (UHPC) is a group or family of materials which has exceedingly high durability and compressive strength. It has also been called “reactive powder concrete,” after a French company patented a material with this name in 1994. It is a high strength ductile material formulated from a special combination of constituent materials. These materials include portland cement, silica fume, quartz flour, fine silica sand, high-range water-reducer, water, and either steel or organic fibers. In the United States, UHPC has been used in bridges and has been formulated from a proprietary material made by Lafarge North America under the trademark Ductal®.
This new family of materials has compressive strengths of 18,000 to 33,000 psi (126 to 230 MPa) and flexural strengths of 900 to 7000 psi (6.2 to 50 MPa), depending on the type of fibers used, and whether or not a secondary heat treatment was used to further develop compressive strength. The material has the capability to sustain deformations and resist flexural and tensile stresses, even after initial cracking.
The durability properties are also excellent. The Federal Highway Administration’s research on Ductal® UHPC showed good long-term creep and shrinkage behavior, excellent resistance to chloride ion penetration, and the ability to hold up well under freeze-thaw testing. ¹
Five bridges to date have incorporated Ductal® UHPC in the United States. The Mars Hill Bridge in Wapello County, Iowa was the first bridge in the U.S. to use UHPC. This 110-ft bridge opened to traffic in 2006, and included UHPC in modified Iowa Bulb-Tee Girders. The Cat Point Creek Bridge in Richmond County, Virginia was the second bridge in the U.S. to take advantage of UHPC. This ten-span bridge was constructed with UHPC in precast prestressed Bulb-Tee girders and opened to traffic in 2008. The Jakway Park Bridge in Buchanan County, Iowa used UHPC in new pi-girders (shaped like the Greek letter p), and opened to traffic in November 2008.
Two bridges in New York State have incorporated Ductal® UHPC as cast-in-place joints between prefabricated bridge decks. The Route 31 Bridge over Canandaigua Outlet used UHPC as the closure material between decked Bulb-Tee elements. The Route 23 Bridge over Otego Creek in Oneonta, N.Y. included UHPC at the joints between 8-in thick precast concrete deck panels.
Recently, the Hawk Lake Bridge in Thunder Bay, Ontario, Canada also used UHPC at the joints between precast concrete box girders. This bridge was a winner in the 2010 PCA Concrete Bridge Awards competition.