Road builders question the practicality of concrete that could last 120 years and significantly cut the industry‘s workload.
Materials researchers have found ways to extend pavement life to more than a century. Konstantin Sobolev, a University of Wisconsin-Milwaukee associate professor, is trying to build on that success and to further improve concrete’s ability to withstand water damage.
Sobolev’s work involves adding different chemicals to concrete that will change the material on a molecular level when the pavement sets. By doing this he can, for example, create a spiky surface that, although microscopic, prevents water from soaking into the pavement.
Using different materials and making sure pavement sets under optimal moisture levels and temperatures in the field can increase costs on the front end but can create a longer-lasting road, Sobolev said.
Such concrete could reduce construction delays for drivers and cut repair and reconstruction costs, said Tom Walker, director of government affairs for the Wisconsin Transportation Builders Association. But the dream must be tempered by the reality that nobody knows what the transportation needs will be in 2130, he said.
It is difficult to gauge whether the higher upfront cost will result in a road that will be useful for its entire life span, he said.
“I’m not trying to be critical at all,” Walker said. “You always try to find the sweet spot between initial cost and life-cycle cost.”
People probably will still need roads 100 years from now, Sobolev said. He said his worry is not upfront cost as much as it is maximizing the value of the limited materials used to build roads.
“You need to really step away from this and use holistic thinking,” Sobolev said. “Can we really go on like this and use the same kind of concrete that we were using 70 years ago?”
Sobolev said he is not concerned about his research putting pavers out of business. The materials used to build roads are wasted on projects with 50- to 70-year life spans, he said.
“You will always need something built,” he said. “But I am against building something and making it a quick fix, because we cannot afford it.”
But those materials would be wasted on roads that last 120 years but are obsolete sooner, said Kevin Traas, WTBA director of transportation policy and finance. For example, he said, road builders in the 1890s had no idea that today’s streets must withstand the weight of 18-wheelers.
“You’ve got to realize that to build 120-year pavement,” Traas said, “it’s going to cost significantly more.”
The future is hard to predict, Sobolev said, but it is foolish to hold onto outdated methods that do not force builders to improve the life span of roads. Researchers have discovered how to achieve longer-lasting roads, he said, but the technology is not applied.
Departments of transportation must change their requirements for the pavement used in road projects, Sobolev said. Builders today are required to follow specific recipes to mix stone, sand and other concrete ingredients. The approach is flawed, Sobolev said, and departments should instead require materials that satisfy performance requirements, such as longer life spans.
“There is no overall durability specification in the United States,” he said. “There is in Europe, for example.”
Walker said there is not enough proof to justify the need to build roads that will last 120 years when changes in technology could force builders to tear highways up and replace them before they pothole.
“Suppose it turns out that the energy of the future is transferring electrical energy from the pavement into the vehicle,” Walker said. “It might not happen. How do I know?”