Bridge concrete not up to snuff

The Ministry of Transportation has penalized the company contracted to work on the Seven-Mile and Bears Pass bridges after tests showed the concrete wasn’t as strong as originally planned.
Ray Kriscuinas, head of MTO’s structural section in Thunder Bay, said the concrete strengths were “marginally lower”–five percent–than those in the project’s original design.
“It doesn’t affect the integrity of the structures,” he noted yesterday, adding the concrete was within the threshold of acceptable strength and those travelling were not at risk.
“Not at all. Not in the least,” he stressed.
Based on formulas used by the MTO, Kriscuinas noted the penalty would work out to a couple of hundred thousand dollars.
Even with the lower-than-expected strength, the concrete still is stronger than before the work was done, Kriscuinas said. He noted the concrete strength was specified for durability reasons, but admitted he didn’t know how much that durability had been compromised.
“I have no idea. Perhaps not at all,” Kriscuinas said. “And not all of it was below the desired strength, either.”
Meanwhile, work on the $1.46-million project won’t have to be re-done. Instead, Kriscuinas said the contractor will apply a sealer to the curb portions of the bridges.
“The contractor will do it at his own cost,” he added, noting the repairs were expected to give both bridges another 25 years. “You won’t see any change in the life-expectancy at all.”
Since a waterproof membrane already is applied between the asphalt and membrane on the highway, Kriscuinas said the road itself won’t have to be sealed.
Meanwhile, Kriscuinas noted this was a fairly common occurrence and one that the MTO factored in when it set standards.
“Mixing concrete is an art as much as [it is] a science,” he said.