Research and application of rock asphalt dry-modified fluid mastic asphalt mixture for reflective crack treatment in asphalt pavements

To overcome the limitations of traditional reflective crack treatment technologies, this study proposes a dry-process rock asphalt–modified Fluid Mastic Asphalt (FMA) method for reflective crack mitigation. A single milling operation of 18 cm depth was performed to completely remove the crack source layer, followed by dense FMA backfilling to suppress the generation of reflective cracks from their origin. Considering that FMA exhibits excellent durability and crack resistance but insufficient high-temperature stability, rock asphalt modification via the dry process was adopted to enhance its rutting resistance. Based on the Mastic Flow for Filling (MaFF) method, FMA-13 mixtures incorporating 1%, 3%, and 5% rock asphalt were designed, with AC-13 and SMA-13 mixtures serving as control groups. The comprehensive evaluation of mixture performance was conducted through rutting, low-temperature bending, and four-point bending fatigue tests. The results show that rock asphalt significantly improves the high-temperature stability of FMA, whereas its low-temperature cracking resistance and fatigue life decrease with increasing rock asphalt content. A comprehensive performance analysis identified 1% as the optimal rock asphalt content. Field validation on the Jiebo Expressway demonstrated that the FMA drilled samples met the void content requirements, exhibiting a dense and uniform structure. Moreover, the rutting depth of the FMA pavement was approximately 34% lower than that of AC-13. The findings indicate that this method can effectively suppress reflective cracks and significantly improve pavement durability under heavy traffic conditions, providing a reliable technical solution for engineering applications.