The Effect of Recycled Wind Turbine Blade GFRP on the Mechanical and Durability Properties of Concrete

Growing concerns about industrial waste have intensified the search for practical reuse strategies in the construction industry. One of the most problematic types of waste is decommissioned wind turbine blades, which are tough, lightweight glass fibre composites that resist conventional recycling. In this study, shredded glass fibre-reinforced polymer (GFRP) recovered from such blades was used to partially replace the 2–8 mm fraction of natural aggregate in concrete at 10%, 20%, 30%, and 40% by volume. X-ray fluorescence (XRF) analysis showed that the material consists mainly of SiO 2 , CaO, and Al 2 O 3 . X-ray computed tomography (XCT) revealed uneven fibre dispersion and a clear increase in porosity. Compared with the control mix, compressive strength reduced by 7–25%, splitting tensile strength by 18–24%, and elastic modulus by 17–35%. All mixes achieved watertightness class W12 (1.2 MPa), though the depth of water penetration increased with GFRP content. After 50 freeze–thaw cycles, frost-resistance class F50 was only met at 10% replacement. While these trends underline the performance trade-offs, they also point to a realistic route for diverting composite waste from landfills, reducing reliance on quarried aggregate and producing ‘green’ concretes for non-structural, prefabricated elements, where moderate strength is acceptable and reducing weight is advantageous.