In recent years, asphalt pavement has been subjected to varied environmental conditions during its service life, conditions that predispose it to deformation and cracking. To enhance the performance of asphalt pavement, rock asphalt has been selected as a modifier due to its good compatibility with virgin asphalt binder and its ability to improve the fatigue cracking resistance of asphalt mixtures. Although scholars have conducted some studies on rock asphalt mixtures, research on the fatigue and self-healing performance of these mixtures under conditions such as ultraviolet (UV) aging and freeze–thaw remains limited. This paper presents findings from a study that employs a combined fatigue-healing test to assess the impact of such complex environmental factors on the fatigue and self-healing properties of fine aggregate matrix (FAM) mixtures containing three types of rock asphalts, i.e., Buton, Qingchuan (QC), and Uintaite Modifier (UM). The analysis of fatigue-healing test results, grounded in viscoelastic continuum damage (VECD) theory, indicates that rock asphalt can extend the fatigue life of FAM mixtures, albeit with a concomitant decrease in their self-healing capabilities. The study further reveals that UV aging, freeze–thaw, and UV aging–freeze–thaw conditions all led to a diminution in the fatigue and self-healing properties of FAM mixtures. However, FAM mixtures containing rock asphalt demonstrated greater resilience against these reductions. Atomic force microscope (AFM) results indicate that UV aging reduced the number of bee-structures and enlarged their area, whereas the incorporation of rock asphalt enhanced the uniformity of these structures’ distribution, thereby improving the fatigue cracking resistance of FAM mixtures. Fourier transform infrared spectroscopy (FTIR) analysis reveals that while UV aging increased the carbonyl and sulfoxide indices within the asphalt binder, rock asphalt is effective in mitigating this effect to a certain degree, thereby enhancing the aging resistance of FAM mixtures.

Both epoxy resin (ER) and SBS are considered effective pavement materials for avoiding ruts. However, epoxy resin asphalt suffers from poor low-temperate performance and a high material cost in practical applications. Aiming to tackle these issues, a new type of composite asphalt modifier (ER-SBS) has been fabricated by combining epoxy resin with SBS. This work prepared modified asphalt with different doping amounts using the above composite asphalt modifier (ER-SBS), intending to explore the properties of composite-modified asphalt and the modification mechanism of the modifier. Furthermore, the effects of the composite modifier at different doping amounts on the viscoelastic property of asphalt were explored through rheological tests, and then the prepared composite-modified asphalt was compared with matrix asphalt and SBS-modified asphalt. In addition, the modification mechanism of the composite modifier was investigated by fluorescence microscopy and infrared spectroscopy. The difference in pavement performance between the composite-modified asphalt and SBS-modified asphalt was compared by a rut test and dynamic modulus test. The research results showed that the composite modifier improved the high- and low-temperature performances and viscoelastic property of matrix asphalt. When the doping amount was raised to 9%, the composite-modified asphalt exhibited better a modification effect than SBS-modified asphalt. The rut test results indicated that composite-modified asphalt demonstrated a stronger deformation resistance than SBS-modified asphalt. The dynamic modulus test showed that the composite-modified asphalt has better viscoelastic properties and temperature sensitivity. Fluorescence microscopy suggested that the crosslinking between the composite modifier and asphalt forms a mesh structure which greatly improves its resistance to deformation. From infrared spectroscopy, the composite modifier clearly functions as a physical modifier.