Asphalt requires regular maintenance as the binder in the surface loses its power, leading to cracks and eventually potholes. Repair always requires large amounts of materials, but a new self-healing asphalt of researchers from TU Delft can make the need for repairs way lower. They introduced steel wool into the binder, which allows to melt and re-bind the asphalt easily without having to add new materials.

In most highways in the Netherlands, road surface construction happens with porous asphalt due to its ability to get rain off the road and its low noise emissions. The problem of porous asphalt is that it is vulnerable to the relatively small amounts of binder in the asphalt losing cohesion, which means that stones get loose and damage the road, requiring large repair operations.

A project by TU Delft has experimented with adding steel wool into the binders. By heating the steel wool with an induction machine, the bitumen in the asphalt is molten again and can expand, binding the asphalt together again. This means that the stones falling out of the road surface are being glued back into the asphalt, lowering the need for repair as the surface stays complete for longer. As repair is required less often, TU Delft's self-healing technology lowers the need for materials, as the existing surfaces can be used for longer.