Specialty chemicals maker Sika Corp. is alerting customers that “suspect cement” containing excessive levels of corrosive chlorides was used in certain batches of grout designed to protect bridge cables.
Cmedinger / Creative Commons
|The problem grout, containing “suspect cement,” was used in the Veterans' Glass City Skyway in Toledo, OH.|
The issue affects certain lots of SikaGrout 300 PT formerly produced at the company’s plant in Marion, OH. The problem involves cement from a third-party supplier that Sika is not identifying.
Sika spokeswoman Diana Pisciotti said Monday (Feb. 6) that the problem had come to light when an end user expressed concern about the grout.
The Lyndhurst, NJ-based company halted production of the grout at the Marion plant in March 2010, then spent months investigating the issue, testing lots, isolating batches, tracking suppliers and customers, and otherwise working to “untangle the issues” involved, said Pisciotti.
In November 2010, the company said, it began an “enhanced” quality control testing regime that included specific testing of chloride levels at all plants. (The company did not previously test specifically for chloride levels in the product.)
In December 2011, Sika posted a notice to its website that it had been “working aggressively” for “the past several months” to address “reports” of the problem.
Increased Risk of Corrosion
Grout is a mixture of water, cement and sand that hardens once mixed. Its purpose in post-tensioning tendons is to protect the steel cables from moisture, road salt and other corrosion contributors.
Sika said the presence of “unanticipated chlorides” in the cement, “of which Sika was not aware, caused certain lots” of SikaGrout 300 PT “to exceed the chloride level listed on Sika’s Product Data Sheet and product label.”
The manufacturer added: “There is a concern that, depending upon the level of elevated chlorides in the grout in installed locations, the risk of corrosion of the tendon strands could increase.
“While this issue could affect the long-term service life of certain infrastructure projects (roads, bridges, etc.) where the impacted grout was used, Sika is unaware of any damage to structures to date arising from this elevated chloride issue.”
Sika could not say how many projects nationwide might be affected by what it called the “suspect cement,” but an Ohio Department of Transportation official has estimated that the grout was used in up to a dozen projects in that state alone.
The grout was “packed into bundles of steel cables that compress the Veterans’ Glass City Skyway’s concrete deck sections” in Toledo, OH, reported the Toledo Blade, quoting an ODOT district planning and engineering administrator. The $273 million Skyway project was built between 2002 and 2007.
Brian M. Powell / Creative Commons
|The Pomeroy-Mason Bridge, over the Ohio River, also used the grout, according to Ohio DOT. Sika has engaged experts to evaluate the grout’s performance in structures where it was used.|
The material was also used on the Perry Street bridge in Napoleon, OH; the Pomeroy-Mason (U.S. 33) bridge over the Ohio River; and “as many as eight other smaller bridges in Ohio,” the newspaper reported.
“It’s [the grout] not an immediate issue,” ODOT administrator Mike Gramza told the newspaper. “But it could impact the life of the structure.”
Gramza said that ODOT’s specifications for project materials included a 0.08 percent limit on chlorides in the grout, a normal industry standard. The Sika grout from Marion had chloride concentrations as high as 0.5 percent, he said.
Samples will be taken from the bridge within a few months for testing, the Blade reported.
Contractors, Owners Notified
Sika says it is notifying contractors and project owners who may have purchased SikaGrout 300PT.
“Sika is collaborating with those entities to conduct testing and forensic reviews in order to determine whether there is a long-term effect on the service life of the structure in question and to recommend remedial actions if needed,” the company said.
“Federal regulatory officials and industry groups have also been notified.”
The suspect cement is limited to lots produced at the Marion facility, Sika said. Other production locations receive their cement from different third-party sources and are not affected.
Almost all SikaGrout 300 PT produced at Marion is identified by the letter “M” at the end of the Lot Number; for example, 092730027M. In addition, Lot 3000015078 was produced at Marion but does not end in M, due a change in Sika’s software system, the company said.
Lot numbers ending in MC were not produced at Marion and are not affected, the company said.
Sika notes that some DOTs and contractors record the grout-bag identification number on the daily grouting inspection reports. Anyone with questions is asked to email Dave White, Director of Technical Service at Sika Corp., or call White at (201) 508-6678.
In addition to halting production of the grout at the Marion plant and increasing its QC regimen, Sika says it has:
• Engaged a team of “independent and internationally recognized grout and corrosion experts” to analyze the potential risks to service life in structures where the product was used; and
• Implemented a long-term testing protocol to evaluate the impact of elevated chloride levels in the performance of the grout.
“As noted, Sika is unaware of any damage to structures to date arising from this elevated chloride issue,” the company said. “We nonetheless encourage and support routine testing of all infrastructure projects to assure that these projects meet service requirements and continue to be safe for public use.”
Established in 1937, Sika Corp. is a leading supplier of specialty chemical products and industrial materials serving construction and industrial markets in the transportation, marine, automotive and other sectors. Sika Corp. is the largest company in the century-old Sika Group.