Mechanical–Hydraulic Performance Assessment of Fiber-Reinforced Porous Asphalt for Climate-Resilient and Sustainable Permeable Pavements

Porous asphalt permeable pavements suffer severe coupled mechanical–hydraulic degradation under warm-rainy climates, raising rehabilitation costs and threatening the long-term sustainability of road infrastructure. This study aims to clarify how fiber type and dosage jointly govern the climate resilience of PAC-13 porous asphalt and provide material-selection guidance for constructing durable, sustainable permeable pavements. Four typical engineering fibers (polyester, polyacrylonitrile, lignin, and basalt) were incorporated into porous asphalt mixtures at mass dosages from 0% to 0.5%. A comprehensive laboratory testing program was conducted to characterize high-/low-temperature performance, moisture-damage resistance, aggregate anti-raveling capacity, drainage permeability, and void water-storage behavior, while novel multi-dimensional evaluation indicators coupling mechanical and hydraulic responses were established to quantify trade-offs induced by fiber modification. The experimental results demonstrate that appropriately dispersed fibers form an interwoven three-dimensional reinforcement network to enhance the structural durability of mixtures; however, excessive fiber dosage occupies interconnected drainage voids and aggravates internal stagnant-water retention. A dosage range of 0.3–0.4% was identified to balance mechanical reinforcement and hydraulic functionality. Polyacrylonitrile fiber delivers excellent low-temperature cracking resistance yet shows high-performance susceptibility to dosage deviations. Polyester and basalt fibers achieve favorable trade-offs among rutting resistance, moisture stability, and permeability, whereas lignin fiber is prone to severe agglomeration that exacerbates void clogging and chronic water-related deterioration. Accordingly, polyester and basalt fibers dosed at 0.3–0.4% are prioritized for high-standard sustainable climate-resilient drainage pavements. Polyacrylonitrile fiber can be adopted for sections primarily threatened by low-temperature cracking under strict construction control, while lignin fiber demands cautious field deployment. This research can provide design support for the use of permeable pavement in warm and rainy areas, and is helpful in enhancing the long-term sustainability of transportation infrastructure in the context of climate change.