Categories | Ready-Mix

Concrete maturity testing goes high-tech on US 10 project

STEVENS POINT, Wis. (March 9, 2007) – They reach toward the sky like concrete trees. And in just a few weeks, the 30 piers that dot the path of the emerging U.S. Highway 10 that traverses the Wisconsin River and other low-lying areas north of the city will be connected by massive concrete bridge girders.

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A ready-mix truck from County Materials rolls past a pier to its next pour as workers lay the foundation for the new U.S. 10 north of Stevens Point. County Materials will supply more than 15,000 cubic yards of poured concrete for the project, more than twice the amount that comprises the McCleary Bridge between Wausau and Rib Mountain.

But first, workers are braving winter winds and temperatures to measure, pour and test some of the roughly 3,600 cubic yards of County Materials ready-mix concrete that will comprise the footings, piers and pier caps that will support the bridge. County Materials will supply more than 15,000 cubic yards of ready-mix for the entire project. That’s more than twice the 6,000 cubic yards the company supplied for the McCleary Bridge connecting Wausau and Rib Mountain, and it would cover the playing surface of Green Bay’s Lambeau Field to a depth of more than 7 feet.

The Wisconsin Department of Transportation (WisDOT) is expanding 31 miles of U.S. 10 between Highway 13 near Marshfield to Interstate 39, north of Stevens Point. The new four-lane highway will bypass several small communities, as well as downtown Stevens Point, where U.S. 10 currently runs. Construction began in 2006 and is scheduled to wrap in 2012.

Making workers’ jobs a little easier is an alternate technology employed by County Materials on the project. Maturity testing loggers, computer chips embedded in the concrete, allow testers to hook up a handheld unit to measure the structure’s internal temperature. This helps workers gauge the rate at which the concrete cures, allowing them to accurately measure the pounds per square inch (psi) the concrete can support at any given time. At 2,500 psi, workers can remove the forms, and at 3,500 psi, they can remove the cold-weather protection. For the U.S. 10 project, the final psi will be 4,000.Ü

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A tester for County Materials checks the readings of some concrete poured for one of the piers at the new U.S. 10 north of Stevens Point. Embedded microchips help workers more accurately monitor the concrete during the curing process.

Previously, the only method by which contractors could gauge concrete’s curing rate was to pour separate test cylinders alongside a project to replicate the structure. The cylinders, which typically required 10-12 days to cure to approved psi levels, are not true representations of a bridge pour. But with maturity testing, cure rate readings are extremely accurate and can substantially speed up a project.

“It’s an additional tool to determine concrete’s strength,” said Mike Hammitt of County Materials. “It reduces the time contractors need to wait to remove their forms from 10 days to three and a half days. So that benefits the contractors – and ultimately the taxpayer, in that they save so much on time and labor – and the DOT benefits by getting a more accurate record of temperature readings as the concrete cures.”

Maturity testing technology is now being utilized by Lunda Construction and Zenith Tech, Inc., the contractors doing the current Stevens Point and Wausau area bridge projects.

County Materials operates 30 locations serving the Midwest. The family-owned, American company is an industry leader in the manufacture and distribution of concrete block, brick, stone, ready-mix, hollowcore, pipe, pavers, retaining walls and Aggregate Finish products for residential, commercial and municipal construction and landscaping.

For more information, call us at 1-800-289-2569 and ask for a product guide.

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