Recycled asphalt pavement (RAP) mixtures are widely adopted due to their significant economic and social benefits from utilizing pavement recycling materials. This study incorporates basalt fibers (BF) and polyester fibers (PF) into plant-mixed hot recycled asphalt mixtures to analyze their enhancement effects on the high-temperature, low-temperature, and fatigue performance at different RAP content levels. Additionally, the study investigates the impact of fiber and RAP additions on the compaction characteristics of the mixtures using gyratory compaction tests, aiming to increase the RAP content of plant-mixed hot recycled asphalt mixtures. Experimental results demonstrate that at 30% and 50% RAP content levels, basalt fibers exhibit more pronounced enhancement effects on the performance of recycled asphalt mixtures compared to polyester fibers. Incorporating basalt fibers increases the fracture energy of recycled asphalt mixtures by 8.63% and 13.9%, and improves fatigue life by 154% and 135%, respectively. Moreover, the addition of both types of fibers increases compaction difficulty, with polyester fibers showing a more significant influence on the compaction energy index (CEI).

With the updates and differences in the usage of reclaimed asphalt pavement (RAP) separation technology, the production of fine-particle RAP exceeds their usage, resulting in an excess of fine-particle RAP. How to apply this excess RAP on a large scale in micro-surfacing technology has become a challenge. This study aims to investigate the advantages and disadvantages of incorporating RAP into micro-surfacing. To this end, a mix design process for RAP-containing micro-surfacing, based on the current gradation design procedure and existing research findings, is proposed. The study examines the influence of six different RAP contents, as well as the effects of SBR emulsified asphalt, added water, and RAP on the micro-surfacing mix design. Subsequently, the effects of RAP content on the pavement performance of micro-surfacing are evaluated through rutting deformation rate, wet wheel abrasion, and British pendulum tests. Finally, an economic analysis from a construction perspective is conducted. The results indicate that the optimized mix design process meets specific usage requirements and is effective for RAP-containing micro-surfacing. The mix design results show that the addition of RAP reduces the asphalt demand and mixing time of slurry mixtures. Increasing the amount of added water can meet mixing requirements, but it leads to a reduction in early strength. As the RAP content increases, skid resistance improves, with a maximum increase of 14.9%; the rutting deformation rate increases, and this is the main factor limiting the RAP content, restricting it to no more than 40%; water damage resistance shows an initial increase followed by a decrease, but this does not affect the RAP content. Therefore, the maximum RAP content is limited to 40% without the addition of other additives, mainly due to the phenomenon of weak agglomeration in RAP. Finally, cost calculations show that incorporating 40% RAP can save approximately 17% of the construction costs.

High-RAP asphalt mixtures are highly susceptible to fatigue brittle fracture. This study investigated the fatigue damage evolution of basalt fiber (BF)-reinforced high-RAP mixtures. Four-point bending fatigue tests were performed to evaluate the stiffness damage factor and the ratio of cumulative dissipated energy change $R_{CEDC}$. The ExpDec2 model and a second-derivative criterion were utilized to quantify steady-state energy dissipation and partition damage stages. Results indicate that BF extended fatigue life, yielding a 55% improvement at 70% RAP content. Model evaluations revealed that in the initial stage, increasing RAP delayed the critical damage inflection point due to accelerated non-steady damage, whereas BF shifted inflection points forward by constraining early damage accumulation. In the stable propagation stage, BF reduced the energy dissipation rates of 50% and 70% RAP mixtures by 44% and 22%, respectively. These quantitative results provide essential performance data regarding the effect of BF on the fatigue life and energy dissipation of high-RAP mixtures, serving as a practical reference for the design and durability optimization of sustainable asphalt pavements.