Technical feasibility of adding 20% wind turbine blade waste to concrete: Fresh, mechanical, deformational, and sustainability assessment

Abstract

The recycling and valorization of decommissioned wind turbine blades represent a pressing environmental challenge. This study explores a recycling route in which the blades were not selectively crushed, thus yielding Wind Turbine Blade Waste (WTBW) composed of balsa wood, polymers, and fibers and microfibers from Glass Fiber-Reinforced Polymer (GFRP). This by-product was subsequently incorporated as a partial replacement (20% by volume) of natural aggregates in concrete. The fresh, mechanical, deformational, and sustainability performance of the resulting concrete was evaluated. 20% WTBW inclusion slightly reduced workability, though concrete maintained a slump class S2 thank empirical adjustment of water and plasticizer contents, in principle ensuring placement by conventional vibration. Mechanical properties were generally reduced due to the weak particles in WTBW. Nevertheless, flexural strength was preserved (5.59 MPa) owing to the three-dimensional reinforcement of the GFRP fibers. Such fiber network also enhanced post-failure performance, doubling the absorbed energy under bending and promoting more ductile failure modes characterized by reduced crack width and absence of surface spalling. Scanning electron microscopy confirmed a proper orientation and crack stitching of GFRP microfibers, which also contributed to this improvement. A cradle-to-gate life cycle assessment showed reductions of approximately 6% in both abiotic depletion potential for fossil fuels and global warming potential, both in total terms and per unit of strength or absorbed energy under bending. These results, statistically validated by an analysis of variance, indicate that concrete incorporating 20% WTBW could, in theory, be sustainably used in elements with reduced mechanical requirements and predominantly bending stresses.