Optimization of composition and mixing process of a self-healing porous asphalt

In this paper, the optimization of materials for the first engineered road with self-healing purposes is shown. For that, steel wool fibers have been mixed in porous asphalt concrete. The idea is to introduce conductive particles in the asphalt mixture, with the objective of heating it via induction energy. This will increase the healing rates in the pavement, closing all possible cracks in it. To define the volume of fibers in the mixture, porous asphalt cores were made at the laboratory. Different requirements for the mixture were that it should be free of clusters of fibers, that the steel wool should resist for a prolonged time, without corroding and without losing mechanical resistances, under water exposition and under salt water exposition, that the mixture should be heatable and that materials should be mixed in less than 3.5 min. With this in mind, it was concluded that 4% of fibers, mixed during 1.5 min was the optimum volume for the pavement. Additionally, two different ways of mixing were tried in an asphalt plant and, to validate the results, a test track was built in a motorway and asphalt cores were taken from it. Different tests included indirect tensile tests, CT-Scan or infrared measuring of the induction heating.