Grout used to protect steel support cables in the Woodrow Wilson Bridge, which carries Interstate 95 over the Potomac River, may be contaminated with an excessive level of chloride, a corroding substance known to accelerate rusting.
The Federal Highway Administration warned 21 states — including Maryland — that as many as three dozen bridges were built with possibly defective grout manufactured in Ohio between November 2002 and March 2010.
Chloride-contaminated grout was blamed in the collapse of a pedestrian walkway at Lowe's Motor Speedway in Concord, N.C. in 2000, injuring more than 100 fans.
In this case, however, federal and state highway officials insist that there is no imminent hazard. The FHA said that the presence of chloride is not an indication of corrosion but "does indicate corrosion potential."
"There isn't any safety issue. There isn't one in the foreseeable future," said David Buck, spokesman for the Maryland State Highway Administration. "There's so much redundancy built into the bridge. But we're keeping an eye on it."
The state agency is halfway through a routine four-month inspection of each span of the 12-lane bridge, Buck said. Crews in "snooper" bucket trucks swing over the guardrail to check the underside of the decking and the bridge supports looking for cracks, discoloration or unusual wear.
"We're not finding anything right now," Buck said.
Maryland and Virginia jointly own the $2.4 billion bridge, which was completed in 2008.
Malcolm Kerley, chief engineer for the Virginia Department of Transportation, said it is important to proceed with caution.
"You've heard the old saying, 'The cure is worse than the disease,' well, you don't want to go out and start doing all this stuff without knowing what the problem is," he said. "Anyone who has dealt with bridges knows you can't guarantee everything, but we can guarantee we are doing everything we are supposed to do."
In a letter to Transportation Secretary Ray LaHood, the heads of the Maryland and Virginia transportation departments expressed concern that the problem could develop so early in the bridge's life span: "After struggling so long collectively to plan, design, fund and build the WWB, we need to ensure its integrity."
About 4 million pounds of grout were used on the Wilson Bridge to seal industrial-grade PVC ducts containing the reinforcing cables for precast concrete segments. The cement-like material acts as a protective coating to fend off moisture and road salt.
But over time, rain water or road spray could ooze through cracks in aging ducts and into chloride-contaminated grout, corroding the steel cables, officials said. In fact, water did leak into Wilson Bridge duct work during construction in August 2003, requiring contractors to pump out the fixtures and seal the cracks with an acrylic gel and a cement-based grout.
In response to a question about the 2003 leaks, the Federal Highway Administration said in a statement last week that "there is no cause for concern."
Buck said any problems would take time to develop, "and if something comes up, we'll deal with it."
The grout is advertised by its manufacturer, Lyndhurst, N.J.-based Sika Corp., as "non-corrosive, does not contain chlorides."
But for more than seven years the company's Marion, Ohio, plant pumped out 20 million pounds of SikaGrout 300 PT, some of which contained levels of chloride as much as 400 percent above industry limits. About 16 million pounds were delivered to bridge contractors across the country, including those in California, Florida and Illinois, according to federal officials.
Sika learned of the problem from state highway officials, who had quality concerns. The company pinpointed the source: the supplier of cement used in the grout, Buzzi Unicem, and its Greencastle, Indiana, plant. The Sika plant stopped making the grout in March 2010 and has not resumed production.
The company conducted its own investigation and contacted states; it informed federal officials on Oct. 26, 2011. Federal officials said Sika has been "forthcoming" about the problem.
Sika spokeswoman Diana Pisciotta said the company has been working with federal and state officials on the problem and is sampling grout to determine which lots were contaminated. Company officials are "unaware of any damage that has occurred related to this chloride issue," Pisciotta said.