After a successful test, construction is planned to begin this summer on the first bridge in the United States made from ultra-high performance concrete.

ISU researchers concluded a series of experiments last week with a test to determine the pressure needed to shear a 71-foot beam made from the material, which is denser then ordinary concrete.

In the test, four hydraulic pumps were used to press down on the beam, and, after two hours and 595,000 pounds, the beam audibly snapped, leaving a diagonal crack nearly three feet long.

Brent Phares, associate director for bridges and structures in the Center for Transportation Research and Education, said the pressure could be compared to 10 semi trucks stacked on top of each other.

The breaking point fell slightly outside the predicted range of 600,000 to 800,000 pounds, although Phares said the deviation was not significant.

“I would guess it’s plenty strong,” said Brian Degen, the project’s research assistant and graduate student in civil, construction and environmental engineering.

He said the pressure was far greater than any pressure likely to be encountered by a bridge in the real world.

“We certainly exceeded what all the available specifications said,” Phares said.

The research received $450,000 in funding with $300,000 from the Federal Highway Administration’s Innovative Bridge Research and Construction Program and $150,000 from the Iowa Highway Research Board, Phares said.

A single-span bridge using three 71-foot beams of ultra-high performance concrete is scheduled to begin construction this summer, said Brian Moore, Wapello County engineer.

He said the three beams for the Wapello County bridge are planned to be constructed between June 25 and July 16 at manufacturer Lafarge North America in Winnipeg, Canada.

Construction on the bridge over Little Soap Creek in the southeastern Iowa county is planned to conclude this fall.

Moore said the decision to use the material was made because $300,000 in federal grant money could be used to offset the higher cost of the special concrete, about three times that of normal concrete. He said the project should cost about half of what a bridge made from normal concrete would cost.

“The federal grant money offset the extra cost,” Moore said.

Phares said ultra-high performance concrete, first made in France during the 1990s, has been used in several projects around the world, including bridges in France, Canada and South Korea. The material is a dense composite of cement, sand and small steel fibers.

Phares said the concrete is more than twice as strong as normal concrete, although it costs several times as much to manufacture. He said high performance concrete is also immune to water corrosion, which is the number one cause of bridge deterioration in Iowa.