Recycling of Retired Wind Turbine Blades into Modifiers for Composite-Modified Asphalt Pavements: Performance Evaluation

With the rapid development of wind energy, large-scale disposal of retired wind turbine blades (rWTBs) has become a hotspot issue worldwide, especially in China. Currently, some practices have reused them in producing artworks, bus stations, concrete structures, etc., but their consumption and value are considered to be very low. Therefore, the recycling of rWTBs into asphalt pavement may be a good way to achieve the goals of large consumption and added value. On this basis, this study first obtained rWTBs crushed and ground into fine powders and then mechanically mixed with styrene–butadiene rubber after silane treatment for the final preparation of the powder modifier (R-Si-rWTB). Afterward, these modifiers were used to prepare composite-modified asphalt mixtures in combination with SBS. Through a series of structure and performance characterizations, the following valuable findings were reached: after the silane and rubber treatments, the microstructure of rWTBs became tougher and almost all of the fibers were coated by the rubber; the R-Si-rWTB modifier had a significant effect on improving the resistances of the asphalt mixture to moisture-induced damage, reaching 95.6%; compared to that of the virgin asphalt mixture (83.67%), the immersed residual Marshall stability of the 30R-Si-rWTB/70SBS asphalt mixture was higher, being between 86% and 90%; the rut depth development of 30R-Si-rWTB/70SBS was very close to that of 0R-Si-rWTB/100SBS, and their dynamic stabilities were close to each other, namely, 5887 pass/mm and 5972 pass/mm; and after aging, the resistances of the 30R-Si-rWTB/70SBS asphalt mixture to moisture and freeze–thaw damage improved. Overall, the value-added recycling of rWTBs into a modifier can contribute to better and more durable asphalt pavement.