Microwave crack healing on conventional and modified asphalt mixtures with different additives: an experimental approach

Abstract

Self-healing asphalt by increasing bitumen temperature using microwave radiation is an effective technique for crack-healing on asphalt mixtures. Normally, these types of asphalt mixtures contain metal additives that promote microwave heating. However, results from the literature suggest that crack-heling would be possible without additives. If this is possible, existing asphalt pavements could be healed by microwave heating. The objective of this research is to evaluate the crack-healing capabilities of conventional asphalt mixtures without metal additives. With this purpose, the authors studied and compared the crack-healing capabilities of conventional asphalt mixtures without metal additives with modified mixtures containing steel fibre, metal shavings, and Silicon Carbide, the last being a novel ceramic material for the crack-healing of asphalt mixtures by microwaves. The authors conducted three-point bending tests on semi-circular asphalt samples to calculate the flexural strength of asphalt. Results of the research showed that the effect of additives that promote microwave heating on the crack-healing of mixtures was a small reduction of the average healing ratio. Additionally, it was found that the effect of additives that promote microwave heating on the surface temperature of samples was either a small increase or small decrease, similar to the effect observed in the healing of mixtures. X-Ray computed tomography results showed that the virgin aggregates used contained metals, which explains the heating and good crack-healing of the reference mixtures. Overall, results of crack-healing tests indicate that asphalt mixtures with aggregates that naturally heat with microwave radiation could be crack-healed without the addition of additives to promote microwave heating.

Keywords:

• asphalt pavements
• crack-healing
• additives
• microwave heating
• silicon carbide
• metal in aggregates

Acknowledgments

The authors extend their gratitude to Luciano Storey from University Federico Santa María and José Luis Concha, from LabMAT at University of Bío-Bío, for their assistance in the laboratory, Erik Schlangen from TUDelft and his team, and Anne Bliss for her assistance in the final review of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Alvaro González http://orcid.org/0000-0002-0353-8581

Jose Norambuena-Contreras http://orcid.org/0000-0001-8327-2236