## 1 Introduction
Many studies have been conducted to investigate the reinforcing properties of basalt fibers on asphalt mixtures, including mechanical behavior, low and high-temperature performance, and water sensitivity [10; 11; 12; 13]. [PERSON] et al. suggested that compared with lignin fiber and polyester fiber, basalt fiber had a more significant impact on improving the performance of asphalt mortar [14]. [PERSON] et al. observed that basalt fibers were randomly distributed in the asphalt mixture matrix and had a strong wrapping force and connection with the matrix asphalt [15]. [PERSON] [16] found that the incorporation of basalt fibers could substantially improve the high-temperature stability of asphalt mixtures. [PERSON] et al. [17] stated that the addition of fibers enhanced the deformation tolerance of the asphalt mixture, although the specific influence of fiber type on the material's low-temperature performance varied. [PERSON] et al. explored the rheological characteristics of basalt fiber-reinforced asphalt mastics and concluded that the incorporation of basalt fibers improved the stiffness, rutting resistance, and cracking resistance of the asphalt binder, but reduced its fatigue performance [18]. The use of bamboo fiber in asphalt mixtures not only reduces the environmental impact but also offers economic advantages. Bamboo forests are abundant and have relatively fast growth characteristics, reaching full maturity within 3 to 5 years, which solves the problem of intermittent scarcity of reinforcement material resources in terms of supply sources [19]. Furthermore, bamboo fiber is an eco-friendly fiber that is degradable, recyclable, low cost and renewable [20; 21]. [PERSON] et al. noticed that including bamboo fibers to asphalt mixtures strengthened their stiffness and durability to cracking at medium temperatures but had no meaningful effect on their high-temperature qualities [22]. [PERSON] et al. [23] observed that the inclusion of bamboo fibers in asphalt mixtures improved their resistance to water damage, rutting, and low-temperature cracking. Similarly, [PERSON] et al. [24] found that the addition of bamboo fibers enhanced the dynamic modulus of asphalt mixtures. While the fatigue life of the modified mixtures was still better than that of traditional hot mix asphalt (HMA) after aging, these findings highlight the potential of renewable fibers as a viable alternative for enhancing the fatigue life of asphalt mixtures in support of sustainable development. Furthermore, [PERSON] et al. recovered bamboo fibers from bamboo residues to enhance asphalt mixture performance, which not only achieved waste utilization, but also delivered considerable environmental benefits and great promotion value [25]. In summary, while fibers are currently being used to enhance the road performance of asphalt pavements, research on fiber-modified asphalt mastic is limited, with a focus on a single type of fiber, and lacking comparison between different types of fibers. Natural fibers have the advantages of being renewable and green, and can improve the overall performance of asphalt mixtures and extend the service life of roads. Their application has good socio-economic benefits and development prospects, making them significant for sustainable development. Therefore, this study selected two natural fibers, basalt fiber and bamboo fiber, to modify the asphalt mastic, providing valuable insights for future research and engineering applications of these fibers in modified asphalt.