From Waste to Worth: Mechanical Performance and Reinforcement Mechanisms of Autoclaved Aerated Concrete with Recycled Wind Turbine Blade Fibers

Abstract With the rapid development of the wind energy sector, a growing number of wind turbines are facing decommissioning, resulting in substantial volumes of waste wind turbine blades. Recycling these composite materials poses a significant environmental and logistical challenge. This study aims to incorporate wind turbine blade fiber (WTBF) into autoclaved aerated concrete (AAC) of B05 grade (achieving a compressive strength of over 2.5 MPa with a dry density between 450 and 550 kg / m 3 ) to enhance the performance and promote sustainable reuse. The workability, physical properties, and mechanical properties of WTBF-reinforced AAC (WTBF-AAC) were comprehensively evaluated. The reinforcement mechanism was systematically investigated through X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The results indicated that AAC reinforced with 1.0% long WTBF exhibited optimal mechanical performance, with a 40.08% increase in compressive strength and an 81.25% increase in splitting tensile strength. Similarly, 0.4% short WTBF improved these properties by 12.84% and 53.13%, respectively. Under autoclave curing conditions (190°C, 1.25 MPa, 8 h) in saturated Ca ( OH ) 2 solution, SiO 2 on the WTBF surface was transformed into calcium silicate hydrate (C─S─H) gel, promoting the formation of tobermorite and enhancing the interfacial bonding between WTBF and AAC. The residual WTBF in the AAC contributed to improved compressive and tensile strengths by its crack-bridging mechanism. This study implies that the utilization of WTBF can effectively mitigate the inherent brittleness and cracking susceptibility of AAC while offering a viable recycling pathway for waste wind turbine blades.