Upcycling waste wind turbine blades into fiber-reinforced asphalt mortar : a chemical recycling approach and performance assessment

Abstract

Wind turbine blades (WTBs), primarily composed of thermoset glass fiber-reinforced polymer (GFRP), present significant recycling challenges and environmental concerns. This study aims to develop an efficient recycling process for glass fibers from WTBs and evaluate their reinforcement effects on asphalt materials at the asphalt mortar scale. A chemical recycling method utilizing solvent treatment is proposed, which successfully extracts high-quality glass fibers. These recycled fibers are then incorporated into asphalt mortar, and mechanical tests are conducted to assess their viscoelastic and damage properties using viscoelastic and viscoelastic continuum damage (VECD) theories. The results indicate that the recycled glass fibers increase the dynamic modulus and reduce the phase angle of asphalt mortar, particularly at lower frequencies. Additionally, a higher fiber content improves the relaxation spectrum and relaxation modulus in time domain. The glass fibers also improve anti-fracture properties, reflected in higher initial stiffness and peak stress. A moderate fiber content enhances deformation capacity and fatigue life, whereas excessive glass fiber content reduces both due to weakened adhesion between the fibers and asphalt matrix. Computational modeling on microstructural models reveals that glass fibers serve as bridging elements within the asphalt mortar, bearing significantly higher stress than the aggregate and matrix, particularly under low-frequency loads, emphasizing the importance of strong fiber-matrix bonding. Overall, this study offers valuable insight into the reuse of WTBs in pavement engineering and highlights the need for future research to improve bonding between recycled glass fibers and asphalt binders.