By Michael Hill
Correspondent
The sound of the concrete — supporting girders for the new Goethals Bridge — collapsing under the weight of more than 13,000 pounds per square inch, about 4,000 pounds higher than its design strength.
“We always design concrete to exceed what we’re looking for,” said Cas Bognacki.
Bognacki is the chief of the Port Authority’s Materials Engineering Unit, a lab in a huge warehouse right before the Holland Tunnel.
Bognacki leads the team that puts concrete to the test for the Port Authority’s bridges, tunnels and airport runways. Several steps go into making sure water can’t permeate the concrete by curing cylinders at 73 degrees in 100 percent humidity in the lab’s moisture room, submerging concrete for 30 days and saturating cylinders with water.
“This is called the rapid chloride permeability test. It will give you an idea of how permeable is the concrete, how easy is it for water to pass through the concrete? We want to make concrete where the water cannot pass through the specimen,” Bognacki said.
Another challenge: minimizing shrinking potential.
“The less potential it has to shrink, the less potential there is for cracks. Cracks are not good for concrete because it lowers the design life of the concrete. Again, through those cracks, water and chlorides will get in, they’ll get into the steel and start the deterioration process quickly,” Bognacki said.
Bognacki says the lab also aims to make concrete more environmentally friendly and it puts additives in concrete to make it more durable and able to last 100 years. All of the results go into specifications for the kind of concrete contractors are to use to build Port Authority projects.
Even after all the extensive and exhaustive testing of the concrete in this lab and the results are shared with contractors, the lab’s work is not done.
“Once it’s delivered to our job site we always take specimens and we always test those specimens to verify that we in fact received what we were told we were going to receive,” Bognacki said.
What’s the message to contractors when they do something like this? When they know Bognacki is going to verify it?
“The message to contractors is that we mean what we say. We expect to get it. And furthermore, our specifications also have payment adjustments. So, if we don’t get what we want, we reduce payments to that contractors,” explained Bognacki. “And that usually gets everybody’s attention.”
Bognacki says it’s an honor that the work here went into the construction of the Freedom Tower and with an impact well beyond one beacon of America’s resiliency.
“The building code was revised because of a lot of the testing we did in reconstructing the World Trade Center. Much that we did there was copied into the code, the New York City Department of Buildings code,” he said.
Bognacki says his is the lab of economical and extra steps because so much is riding on getting it right.