Paved roads are easily damaged, can be noisy, dirty, and costly to repair. Erik Schlangen designed a new type of porous asphalt made with simple materials, which when cracked can be “healed” by induction heating. The porous asphalt has steel fibers embedded in bitumen, which when heated by an induction heating machine, can melt back to the original shape and increase the life span of the road.
Porous asphalt is now used in most of the Netherland’s highways. The water can run through the pores and flow away to the sides, leaving the road easy to drive on and with no rain water splashing. The noise can also travel through this very hollow material, leaving the road silent.
Potholes that can appear in the asphalt, are dealt with by using “self-healing” materials. Steel wool, same as the one used for cleaning pans, is cut into very small pieces, and mixed with bitumen. An induction heating machine can heat up the steel and bitumen. As the bitumen melts, it flows into the micro-cracks between the steel fibers, and the fallen out stones are again fixed to the surface of the road.
The government of Netherlands donated to Erik’s team a 400 meter long piece of the A58 highway for a test trial of this new asphalt. “This road will last several years without any damage. So we took a lot of samples from this road and we tested them in the lab. So we did aging on the samples, did a lot of loading on it, healed them with our induction machine, and healed them and tested them again. Several times we can repeat that. So actually, the conclusion from this research is that if we go on the road with our healing [induction heating] machine every four years – we can double the surface life of this road, which of course saves a lot of money.”