Study on the Application of Recycled Polyester Fibers in Stone Matrix Asphalt Mixtures

In order to study the effect of recycled polyester fiber on the road performance of the SMA asphalt mixture, a method of improving the road performance of asphalt concrete by recycled polyester fiber/lignin fiber composite was proposed. By using the method of 1:1 compounding of recycled polyester fiber and lignin fiber in the SMA-13 mixture, the optimum gradation and optimum asphalt-aggregate ratio of the mixture under the compounding ratio were determined by the Marshall test. The optimum mixing process of the composite fiber was determined, and the road performance of the mixture under the conditions of no fiber, recycled polyester fiber/lignin fiber 1:1 composite, and 0.3% lignin fiber addition was compared. Through a high-temperature rutting test, immersion Marshall test, low-temperature bending test, and four-point bending fatigue test, the mechanical properties of SMA asphalt concrete and the improvement effect of road durability were comprehensively evaluated and verified. The experimental results show that compared with the SMA asphalt mixture without fiber and 0.3% lignin fiber, the high-temperature rutting resistance of the composite fiber SMA asphalt mixture is obviously improved and the recycled polyester fiber can improve the low-temperature crack resistance, fatigue deformation, and water stability of the asphalt mixture. When the ratio of recycled polyester fiber to lignin fiber is 1:1, the dynamic stability of SMA asphalt concrete is 1.1 times that of the single addition of lignin fibers. The maximum flexural strength of the specimen at low-temperature failure is increased by 12%, and the fatigue life is increased by 24%. Lignin fiber increases the thickness of the oil film through adsorption, while recycled polyester fiber enhances adhesion, reinforcement, and the interface effect. By integrating adsorption stability with reinforcement bridging and load transfer, the stability of asphalt concrete under temperature changes, water damage, and stress is strengthened, thereby further improving the durability of the SMA pavement.