Workers may have to remove 220 yards of concrete from the central pylon at the I-280 Maumee River Crossing project because tests have determined that some of the concrete is substandard.
The problem, attributed to a mechanical malfunction at the project's on-site concrete plant, was identified during routine testing done on all batches of concrete used to build the $220 million bridge, said Joe Rutherford, an Ohio Department of Transportation spokesman.
Concrete for the pylon, which when finished will tower 400 feet above the river and support stay cables holding up the six-lane bridge, is supposed to withstand 10,000 pounds per square inch of pressure. However, test samples from a particular 120-cubic-yard batch poured in January failed after passing the 8,000-pound threshold during strength
tests performed on March 9, Mr. Rutherford said.
ODOT and Fru-Con Construction Corp., the general contractor for the bridge project, are reviewing the situation to determine if there are any engineering alternatives to removing the concrete. To remove it, Fru-Con also would lose a 100-cubic-yard layer that was poured on top of it before earlier tests revealed that there might be a problem.
"We've been working with Fru-Con on this since January,'' Mr. Rutherford said.
About 20 feet of the pylon is involved, he said, estimating the problem's potential cost at $500,000.
Because of a crane accident Feb. 16 that halted assembly of the bridge's approach spans, the pylon problem is not expected to affect the project's revised construction schedule, said Mike Gramza, ODOT's project manager.
The Feb. 16 collapse of one of two mammoth truss cranes being used to hoist and hold bridge deck segments into place killed four workers and injured four others. An investigation of the accident continues.
Steve Houston, a Fru-Con spokesman, confirmed that a "quality-control team" from the company and ODOT are investigating and discussing the matter.
"This concrete was tested after seven, 21, and 56 days. Concrete gets stronger with age. But on the 56th day, this batch still didn't pass," he said. "We are exploring potential solutions."
Mr. Rutherford said the concrete deficiency was traced to a malfunctioning piece of equipment in the project's on-site concrete plant, operated by Integrated Resources, a Fru-Con subcontractor.
The malfunction meant that an insufficient amount of cement was mixed into a batch of concrete.
Concrete is made using a mixture of aggregates, cement, and water, along with chemicals and, on this project and many others, steel-mill slag. The chemicals and slag affect the concrete's strength, cure rate, water permeability, and other properties.
An estimated 180,000 cubic yards of concrete are expected to be used in the bridge project. Inspectors working for Bowser-Morner, Inc., a Fru-Con subcontractor, take samples from every truck that leaves Integrated Resources for on-site testing, and ODOT inspectors periodically perform duplicate tests to check Bowser-Morner's results.
Jeff Baker, ODOT's project construction manager, said samples have been taken from the affected portion of the pylon itself for a "detailed stress analysis," and calculations will be made to determine whether the section of 8,000-psi concrete is acceptable.
Detection of the pylon problem is proof that the testing and inspection system is working, Mr. Rutherford said.
One previous concrete defect has been made public on the project. In September, someone at Integrated Resources inadvertently switched bags containing cement and slag for a batch of concrete used to make deck segments. Inspectors noted almost immediately that the concrete was the wrong color, and the material did not cure properly. Three bridge segments poured with that concrete were re-cast.
Fru-Con is expected to give ODOT officials its proposals for resuming bridge assembly, following the crane accident, next week. But Todd Audet, the transportation department's district deputy director, noted that the "work-forward" plan will have to be reviewed by ODOT and the Occupational Safety and Health Administration, which is investigating the accident, before bridge assembly can resume.
Contact David Patch at:
dpatch@theblade.com
or 419-724-6094.
First Published March 26, 2004, 12:31 p.m.
