Vermont's first major design-build project relies on enhanced productivity and accelerated production provided by high-early-strength Lafarge Type III cement.
When officials secured funding for the Cross Street Bridge in Middlebury, Vermont, they wanted to move the project from concept to completion quickly. An aggressive design-build project delivery method, combined with the use of Lafarge Type III cement to maximise productivity and accelerate production, helped open the bridge in just 18 months.
The Cross Street Bridge provides a vital second crossing over Otter Creek to alleviate traffic congestion and connect residents and visitors to the city's downtown shopping district. The US$16 million two-lane bridge is the first major design-build transportation project in Vermont, and the longest simple-span precast, post-tensioned, spliced-concrete-girder bridge in the US. It has won two PCI Design Awards, sponsored by the Precast/Prestressed Concrete Institute, in recognition of its design and construction excellence.
To maximise cost-effectiveness of the process, and meet the timeline of the design-build process, the bridge was constructed using local materials, including high-early-strength Type III cement from Lafarge for the precast, prestressed concrete sections. Lafarge Type III cement's high early strength allows forms to be reused more quickly than with conventional cement.
The bridge design addressed environmental concerns by spanning the entire channel with no supporting structure in the river. The three-span structure includes two 120-foot-long approach spans and a 240-foot-long center span. Each approach span features 10 adjacent box beams cast with 8000-psi self-consolidating concrete. The centre span includes five modified New England bulb-tee girder lines, which were cast with a 10,000-psi self-consolidating concrete mix to meet the design demands on the large girders. The low-maintenance, highly durable concrete superstructure includes an eight-inch concrete deck with three inches of pavement and two six-foot-wide sidewalks that provide pedestrian access.
In addition to its strength in construction, the bridge also includes many aesthetic features that set it apart from typical highway crossings, such as cantilevered pedestrian outlooks over the river, architectural treatments on the abutment and retaining walls, precast ornamental bridge pilasters, decorative lighting, and unique concrete pier geometry inspired by the Brooklyn Bridge.
Adapted from press release by Katie Woodward
Read the article online at: https://www.worldcement.com/the-americas/12092014/vermont-bridge-uses-lafarge-cement-476/