Dutch researchers design highways that heal themselves

Researchers at the Delft University of Technology (TU Delft) in The Netherlands are paving the way to longer-lived roads with a special type of asphalt containing long steel fibers. Zoab, a highly porous asphalt concrete used commonly in The Netherlands, is used because water can drain through openings in the pavement. The problem is that temperature cycles of wet and dry or wet and cold, UV lighting and traffic loads make zoab brittle. With steel fibers added to the mix, the asphalt can be heated to 60-70 degrees C. with a vehicle specially equipped with a heating coil. This softens the asphalt, closing the tiny cracks in the road—and increasing the life-span of paved surfaces to 12 years, if the heating process takes place at least once a year. “We want to discover how often the material must be heated to extend its lifetime,” says Dr. Erik Schlangen, professor of civil engineering and geoscience at TU Delft, “and how this depends on climatic situations.”