Composite bridge material tested in Missouri

University of Missouri-Columbia researchers have developed a new composite reinforcement system that could replace steel rebar and significantly cut down on maintenance and safety concerns for bridges.

The Farm Road 148 Bridge in Greene County Missouri will be the first real-world test of the composite material, which engineers say is up to five times stronger than steel and a fifth of the weight. Construction is slated for the end of summer.

“With the increasing number of vehicles on the road, these older bridges, which were not designed to handle this much traffic, are getting punished more than ever,” said Vellore Gopalaratnam, MU professor of civil and environmental engineering.

Gopalaratnam, along with MU graduate assistant Kenny DeYoung and undergraduate student Sarah Craig, worked on the project with the University of Missouri-Rolla and the Missouri Department of Transportation. The two-year-old project saw its first public demonstration yesterday.

The composite rebar is constructed from a mixture of carbon, glass and polypropylene fibers. Lab testing of the material consisted of using a wrecking-ball machine that pounds into the concrete slab, simulating traffic pressure.

But only real-world use of the technology can reveal its positives and negatives. “The best proof in the pudding is looking at it in real life,” Gopalaratnam said.

Initial use of composite material revealed it was not as tactile or stiff as steel. The addition of other elements, such as glass and polypropylene, addressed that issue.

Gopalaratnam said the idea for the project came after reports showed how states using corrosive deicing fluids and other elements significantly reduced the life of bridges. He said the new composite materials are resistant to corrosion.

At least six other states are experimenting with composite materials in road construction. Canada has been using the technology for almost eight years. “In that sense, we are not the first,” Gopalaratnam said.

Commercial interest is driving the development of composite material technology. Hughes Brothers, based in Seward, Neb., is providing Gopalaratnam with raw materials for the project.

The U.S. Federal Highway Administration’s Innovated Bridge Research Construction program has given at least $32,000 for the MU project. Gopalaratnam will submit additional funding proposals to the National Science Foundation and MODOT.

John Wenzlick, research and development engineer with MODOT, said while the use of composite materials for bridges is impressive, the cost will have to be reduced before widespread application takes place. He said the new material would cost nearly three times as much as traditional concrete and steel.

Gopalaratnam acknowledges while the technology is currently more expensive, it will decrease with time. He said if states began to adopt the use of composites for road construction, manufacturers would increase production and prices would drop.

Labor costs could also be less expensive. Since the composite-reinforced concrete slabs are much lighter than their traditional counterparts, fewer workers would be needed to put them in place.

But Gopalaratnam doesn’t think this will be a huge factor.

“I don’t think it would effect the overall labor count,” he said.

Patrick Beeson can be contacted at pbeeson@randallpub.com.