RESUMO
Self-healing in asphalt mixtures is a property that can be enhanced by external heating, which causes a thermal expansion that increases the flow of bitumen with reduced viscosity through the cracks. Therefore, this study aims to evaluate the effects of microwave heating on the self-healing performance of three asphalt mixtures: (1) conventional, (2) with steel wool fibers (SWF), and (3) with steel slag aggregates (SSA) and SWF. After evaluating the microwave heating capacity of the three asphalt mixtures with a thermographic camera, their self-healing performance was determined with fracture or fatigue tests and microwave heating recovery cycles. The results demonstrated that the mixtures with SSA and SWF promoted higher heating temperatures and presented the best self-healing capacity during the semicircular bending test and heating cycles, with significant strength recovery after a total fracture. In contrast, the mixtures without SSA presented inferior fracture results. Both the conventional mixture and that containing SSA and SWF presented high healing indexes after the four-point bending fatigue test and heating cycles, with a fatigue life recovery of around 150% after applying two healing cycles. Therefore, the conclusion is that SSA greatly influences the self-healing performance of asphalt mixtures after microwave radiation heating.
RESUMO
Asphalt rubber mixtures have been used as pavement surface layers due to their ability to prevent early degradation, and are considered a sustainable option. This study performed analysis comparing the fatigue resistance of asphalt rubber mixtures of different combinations of asphalt bases, crumb rubber, and gradation, in order to estimate the performance of asphalt rubber mixtures as pavement surface layers. The methodology was developed in a laboratory and involved asphalt rubber production by continuous and terminal blend systems with different crumb rubbers and asphalt base types. Asphalt rubber mixtures with varying gradations and an unmodified asphalt mixture as a reference were produced. The mechanical behavior as a dynamic modulus and with respect to fatigue resistance was evaluated using a four-point bending test. In order to verify each of the asphalt rubber mixtures' contribution as a surface layer, pavement structures were designed and their lifespans were compared. The findings showed that all asphalt rubber mixtures presented higher fatigue resistance than the reference. For pavement design, in comparison with the reference mixture, the thickness of the surface layer could be reduced by at least 50% while achieving the same life, proving its successful performance. This study demonstrated the effective contribution of crumb rubber from scrap tires as an asphalt modifier for producing sustainable mixtures with adequate fatigue performance.
