Novel cold asphalt mixture featuring fast curing and self-healing by means of magnetic induction

Abstract

Cold asphalt mixtures require a longer curing time and have lower durability than hot asphalt. So, a novel cold magnetic asphalt mixture with industrial by-product and control mixture with virgin steel fibers was designed and compared with a traditional reference mixture curing by oven according to U.S. standard. The research has two main chapters: first, a novel curing process by magnetic induction was evaluated; second, the self-healing capacity of the same magnetic cold mixture by magnetic induction was assessed. In the first chapter, fast curing by magnetic induction was compared with the traditional method established by the U.S. Asphalt Institute with respect to evaporated water, time and energy used. Also, the binder was evaluated after the curing process by the penetration test, ring and ball and Dynamic shear rheometer. Finally, the complete mixture was evaluated mechanically by means of the Cantabro test, stiffness modulus and indirect tensile strength. Regarding the results, the novel magnetic induction curing method evaporates the same water percentage using less energy reducing the curing time from days to only hours. In addition, the binder of the experimental mixture with by-products was less affected at the rheological level. Regarding mechanical properties, the experimental mixture shows a statistically equivalent performance than control and reference mixture. In the second chapter, the self-healing capacity was determined by means of a rupture-healing-rupture test. Then, the healing process was applied in different cycles of the Cantabro test to evaluate its impact on durability against particle loss. Finally, the permeability was measured after 20 cycles of healing. Results show the experimental mixture achieved 83% self-healing. In addition, applying a heal cycle every 50 revolutions in the Cantabro test allowed tripling the durability against particle loss. Finally, the repetition of healing cycles in the cold mixture affects the internal structure of the mixture, reducing permeability.