Evaluation of the effect of Waste steel Shaving, damage severity and strain level on the healing behavior of asphalt mixtures at different damaging-healing cycles

Abstract

• The effect of strain and damage level and the healing method on the performance of HMA is studied. • Increasing the strain level leads to better healing performance in the first damaging-healing cycle. • The healing performance is improved at low strain levels even if any heating is not applied. • Using WSS additive causes non-uniform temperature distribution during microwave induction. • Using WSS increases the absorption speed and heat loss during microwave induction. By the repetition of damaging-healing cycles, the healing potential of asphalt mixtures declines, and some parameters, such as the strain level, damage level, healing method, and temperature can also affect the healing performance of asphalt mixtures. This study aimed to investigate the effect of Waste Steel Shaving (WSS) additive, healing method (with induction heating or at room temperature), strain amplitude, and damage level on the healing performance of asphalt mixtures. The semi-circular bending (SCB) fracture test was used to assess the impact of WSS, and the four-point bending beam fatigue test, which was carried out at various damaging-healing cycles, was used to explore the impact of strain level, damage level, and healing technique. The findings revealed that although adding WSS improved the heating rate, it had a detrimental impact on the heating distribution in the mixture, causing the specimen to heat up unevenly and to overheat in certain areas. The initial healing cycle's healing performance was improved by raising the strain level. However, by the repetition of damaging-healing cycles, the positive effect of the strain level decreased and in some cases this parameter affected the healing performance adversely. Increasing the damage level reduced the healing potential, and the effect of damage level on the healing potential was greater than heating during the rest time. Therefore, for a better healing performance, it is recommended to control the damage level when the heating equipment is not available.