State gets first bridge with a new technology
Bridge to the future
Wednesday, September 25, 2013
Motorists crossing the Maries River barely slowed Tuesday morning as they drove past the two cranes moving a concrete girder into place for a new bridge on U.S. 50.
But those drivers were passing a little history in the making. The girder is the first in Missouri to be built this way on the MoDOT system, said Jennifer Harper, a state Transportation department research engineer.
“These new girders are going to give us a more durable product at the same cost — or cheaper,” she said.
MoDOT and some researchers at Missouri University of Science and Technology, Rolla, have been studying the technology for a couple of years.
“Some states have been using it for a little while,” Harper said. “The thing is, when you make this self-consolidating concrete, the type of materials you use can make a big difference in how well it works.”
And the materials vary from one region to another, so one state’s experience may not be the same as another.
John J. Myers, a Missouri S&T civil, architectural and environmental engineering professor, has spent the past decade studying and testing high-strength concrete and other innovative concrete systems.
“Self-consolidating concrete freely flows into a form,” he explained Tuesday. “In traditional concrete, you normally have to have extra labor to vibrate the concrete, to make sure ... everything is evenly distributed.”
So, the newer technology should mean less time spent on each girder.
And those girders should be stronger than traditional girders used in bridge construction, Myers and Harper said.
The new U.S. 50 bridge over the Maries River also is using a different form of concrete in some of the piers by using fly-ash in place of some of the cement.
“Fly-ash costs a fraction of what the (Portland) cement costs,” Myers said, “and we’re able to recycle it out of the coal-burning power plants.
“This is really an exciting thing for the contractors and the industry because this makes the cost of the concrete come down quite a bit. And it’s also environmentally friendly, because we’re taking fly-ash out of the landfills.”
Monitoring equipment has been added so the engineers can keep track of how the girders and piers function as traffic crosses the bridge, and in all kinds of weather.
The sensors on the Osage County project communicate with a wireless network that the researchers can see in Rolla, and have real-time information.
The new bridge is part of the new four-lane section of U.S. 50 being built between the U.S. 50-63 interchange north of Westphalia and west of Linn.
Traffic should be using the new highway section a year from now.
And while the engineers are excited about the new technology, Harper said motorists “will, probably, never notice a difference.”
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