Over the past few years, most people in the concrete industry have heard about pervious concrete—both its successes and its failures. But there was often no clear understanding of what led to success. John Kevern has helped define how to make pervious successful and for that he is one of CC’s Most Influential People in 2012.
“I’m working on making pervious easier and more reliable to install,” he says. “Part of the reason we’ve had failures is that for a long time we promoted it without any specifications or test standards. We would just ask the producer for pervious and they would produce something without any specs and the contractor would accept it. Unfortunately when it went south, it was the contractor’s fault. So I’m trying to reduce the liability on the contractor’s side by applying specifications—is the producer making a good product and how does the contractor know it’s a good product? So we can hand off some of the liability.”
But Kevern’s work doesn’t end there. With the huge potential pervious has, he also is working to make it easier to work with. “We are developing admixtures and mix proportioning to make it much less temperamental,” he says. One of the significant advances is an internal curing admixture—a superabsorbent polymer that keeps the concrete curing effectively for five days. “I haven’t put plastic on pervious for a year and a half now,” says Kevern.
An interesting pervious project that he’s been working on is a photocatalytic pervious concrete shoulder on a highway in St. Louis. “It functions like a catalytic converter in a car to react using sunlight to break down pollutants. We’ve done it for air quality and found that the pervious is considerably more reactive than traditional concrete due to the higher surface area and because the surface gets a little warmer so it reacts more quickly.” They have also learned that the photocatalytic concrete reacts with oil spills so that the oil is degraded before it can flow through the concrete.
Another pervious concrete research project Kevern is involved with is a test pavement (a 4-inch overlay) in Minnesota. This is for regular highway travel and was looked at for skid resistance and noise reduction. After four years, it remains in great shape and “it’s the quietest concrete pavement we’ve ever tested in the United States,” says Kevern.
University research often seems so theoretical that its application to actual construction is difficult to imagine. We need more professors like Kevern to bring solutions to real-world problems that can create markets, such as pervious concrete.