After five years of collaboration involving the Federal Highway Administration (FHWA), the Iowa Department of Transportation (IDOT), Iowa State University/Bridge Engineering Center, and Lafarge North America, the first highway bridge in North America built with Lafarge's ultra-high-performance, fiber-reinforced Ductal concrete opened on May 5 in Wapello County, Iowa. The single-span Mars Hill Bridge consists of three 110-ft. Ductal girders with no rebar for shear stirrups. Erected under the “Innovative Bridge Construction Program,” it is part of the FHWA's “Bridge of the Future” undertaking.

Lafarge's Ductal offers a combination of properties, including durability, aesthetic flexibility and compressive strengths to 30,000 psi and flexural strength as high as 6,000 psi. Among those in attendance at the ceremony were Brian Moore, Wapello County engineer/zoning administrator, and Lafarge, Ductal Vice President and General Manager Vic Perry.

Perry says that the next step for Ductal is a fully optimized bridge. “We are testing Pi girders, which are basically double-Ts with bulbs on the bottom. We put strand on the bulbs and then we can create a 3-in.-thick, 8-ft.-wide deck with no rebar and a 2¾-in. web,” he says. “We could place an 8-ft. section in less than an hour, actually more like 30 minutes. Then you just fill up the joint with grout, put on a nonskid surface, and you're good to go.”

The good news for Lafarge is that IDOT has plans on the board for just such a bridge to be completed in 2007, with FHWA currently carrying out full-scale load testing. “We haven't purchased a full line of steel forms for the optimized bridge just yet, but we're close,” Perry says. “Lafarge recognized when it introduced Ductal to North America that it would take at least seven years to get the first optimized bridge built. Our focus was always on long-term objectives. Conventional beams are fine, but there is a need for new decks that last longer. So, Mars Hill is an important incremental step toward an optimized solution.”