First UHPC Bridge in the US to use a Reduced Steel Fiber Dosage
The pioneering Gratiot Road Bridge sets a new standard for cost-effective UHPC bridge construction, utilizing an optimized 1.5% steel fiber content without compromising performance.
Gratiot Road Bridge Over the Moak Drain – St. Clair County, Michigan, Opened to traffic 12/2023.
Steel fibers account for 50% - 70% of the raw material cost of UHPC. Reducing steel fiber content is a highly effective way to reduce overall UHPC cost. With the new AASHTO UHPC Design Guide’s focus on performance and NOT quantity of steel fiber, cost reduction through lower dosage is now feasible with HiPer Type X steel fibers.
The bridge below has a 100% UHPC superstructure and replaces a deteriorated reinforced concrete bridge over a drain. It is the FIRST bridge in the US to utilize only 1.5% by volume of steel fiber (200 lb per cubic yard) in its joints. Compare that to the typical steel fiber dosage of about 3% by volume steel fibers (400 lbs per cubic yard). For example, the Delaware Memorial Bridge used 3.25% steel fibers by volume (430 lb per cubic yard).
The reduced dosage resulted in UHPC performance parameters that were well in excess of the design values, thus opening the door to further reduction in steel fiber amount and hence greater savings.
