Optimized incorporation of shredded wind turbine blade waste in concrete using a particle packing approach

The sustainable management of end-of-life wind turbine blades (WTB) represents a critical environmental challenge due to their complex composite structure and non-biodegradable nature. This study investigates the incorporation of shredded wind turbine blade (SWTB) waste into concrete as a multifunctional component. By utilizing the particle size distribution of SWTB (0.063–80 mm), the waste was integrated to simultaneously function as a partial cement replacement, aggregate substitute, and fiber reinforcement. A particle packing-based mix design approach using the Modified Andreasen and Andersen (MAA) model was employed to optimize the concrete skeleton. Four mixtures with SWTB contents of 0%, 1%, 3%, and 5% by total mass were evaluated. Experimental results demonstrate that while SWTB increases water and superplasticizer demand, the optimized packing structure maintains high mechanical performance, with 28-day compressive strengths exceeding 45 MPa. Even at the highest replacement level, this structural-grade performance was achieved alongside a simultaneous replacement of 10.2% vol. aggregate, 4.4% vol. cement, and 2.6% vol. fiber. Isothermal calorimetry revealed that epoxy residues do not retard hydration, while the fibrous fraction provided a significant toughening mechanism, increasing residual flexural strength by up to 250%. Durability assessments confirmed that SWTB does not trigger alkali-silica reactions (ASR). The findings suggest that the proposed design approach enables high-volume valorization of SWTB without compromising the structural integrity of the concrete, providing a scalable alternative to the landfilling of WTB waste.