THE CONCRETE BRIDGE MAGAZINE

SUMMER 2007

ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.

Issue link: http://www.aspiremagazinebyengineers.com/i/306900

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26 | ASPIRE , Summer 2007 When Neil Armstrong took his first historic step on the moon in 1969, he declared it to be "One small step for a man, one giant leap for mankind." Perhaps the bridge builder's equivalent of that "giant leap" was taken recently on a small rural stretch of highway in Wapello County in the southeastern corner of Iowa, where a new concrete material offers great potential for future bridge designs. The Wapello County Mars Hill Bridge comprises three 110-ft-long precast concrete modified 45-in.-deep Iowa bulb-tee beams topped with a cast-in- place concrete bridge deck. The concrete offers such considerable strength that the beams were built without any shear reinforcement. The ultra-high performance concrete (UHPC), called "Ductal," was supplied by Lafarge North America and achieves up to 30,000 psi compressive strengths, with ductility. Originally developed in France a decade ago, UHPC is produced with materials commonly found in concrete such as cement, silica fume, sand, high-range water-reducer, and water, plus other unique materials like ground quartz and steel or PVA (polyvinyl alcohol) fibers. profile Mars Hill Bridge / WAPEllo County, IoWA EnginEEr: Iowa Department of transportation, Ames, Iowa gEnEral ContraCtor: Bloomfield Bridge and Culvert, Inc., Bloomfield, Iowa Pr EC astEr: lafarge Canada Inc., Winnipeg, Manitoba, Canada, a PCI-Certified Producer BridgE dEsCriPtion: 24-ft 6-in.-wide by 113-ft-long single-span bridge A Whole new cast by Wayne A. Endicott innovative concrete used on iowa bridge eliminates reinforcement and creates new concept for precast concrete bridges ASPIRE_Summer_2007.indb 26 5/15/07 11:42:06 AM

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