Effect of air voids content on asphalt self-healing via induction and infrared heating

- The self-healing properties of asphalt mixtures were studied.
- Self-healing was promoted using infrared and induction heating.
- A new healing model was proposed for asphalt materials.
- The effect of gradation and voids content in healing properties was assessed.
- The relationship between the applied energy and healing ratio was obtained.

Cracks in asphalt roads can self-heal if enough resting time is allowed. Asphalt self-healing is a viscosity related phenomenon that accelerates with the temperature of the material. In the present paper, asphalt self-healing has been induced in cracked asphalt beams with three air voids contents: 4.5%, 13%, and 21%, by exposing them at various times under infrared radiation and induction heating. Infrared heating has been used to simulate solar radiation. Results show that cracks in asphalt mixture can be completely repaired by infrared and induction heating, but the last one is more energy efficient since the effect is concentrated only on the binder instead of heating the whole asphalt mixture. Moreover, it has been observed that dense mixtures obtained better healing with low energy but the maximum healing ratios obtained by them were lower than those obtained by semi-dense and porous mixtures. A new healing model was proposed involving not only surface tension, hydrostatic forces and energy dissipation (included in previous models) but also other factors, such as differential temperature between aggregates and binder and thermal expansion.