Recycling waste wind turbine blade materials in asphalt binder: investigation into compatibility, dispersion, aging, and rheological performance

Decommissioning of waste wind turbine blades (WTBs) presents a significant environmental challenge due to the rapid expansion of wind energy and the lack of effective recycling solutions for glass fiber-reinforced polymer composites. This study investigated the feasibility of incorporating mechanically recycled waste WTB materials into asphalt binder. In addition, corn oil was used to pre-treat WTB materials to enhance intermediate- and low-temperature performance. WTBs were shredded, ground, sieved to obtain a powder (< 75 μm), and mixed with the asphalt binders at 1%, 5%, and 10% dosages by weight. The effects of these modifiers on the rheological properties of the binder, including high-temperature rutting resistance, intermediate-temperature fatigue cracking resistance, low-temperature thermal cracking resistance, aging resistance, storage stability, and dispersion, were assessed using Dynamic Shear Rheometer (DSR), Bending Beam Rheometer (BBR), and optical microscopy. The results showed that untreated WTB materials significantly enhanced the high-temperature rutting resistance and aging resistance of the binder but reduced cracking resistance at intermediate- and low-temperatures. Conversely, WTB materials pre-treated with corn oil improved fatigue, thermal cracking resistance, and storage stability by lowering the binder's stiffness and by improving flexibility. Corn oil-treated WTB materials at lower dosages (<5%) achieved the most favorable overall performance by improving fatigue and low-temperature cracking resistance without significant change in rutting resistance. The study demonstrates that combining WTB materials with corn oil enables a balanced improvement in the binder's high-, intermediate-, and low-temperature performance along with storage stability, aging resistance, and dispersion. These findings provide a promising pathway for transforming end-of-life WTBs into value-added asphalt binder modifiers, thereby promoting waste valorization and circular material utilization and supporting the development of cleaner pavement materials.