A novel approach for upcycling GFRP from decommissioned wind turbine blades into geopolymers via ultrasonic activation

The environmental burden caused by decommissioned wind turbine blades (DWTB) has become increasingly severe with the growth of the wind energy sector. While the geopolymer technology can be used to recycle DWTB by alkali-activating glass fiber-reinforced polymer (GFRP) derived from DWTB, the low reactivity of GFRP results in poor properties of the generated geopolymers. This study proposed an ultrasonic activation method to improve GFRP’s reactivity and investigated physico-mechanical properties of geopolymers from ultrasonication-modified GFRP using X-ray photoelectron spectrometer, scanning electron microscope, and Mercury Intrusion Porosimetry (MIP). The experimental results demonstrated that ultrasonic treatment significantly enhanced the GFRP’s reactivity by detaching the epoxy resin from glass fibers. Ultrasonic activations under both elevated (60 °C) and low (−10 °C) temperatures yielded superior GFRP reactivity compared to processing under room-temperature. The 28-day compressive strength of GFRP-based geopolymer reached 31.23 MPa with ultrasonic treatment, representing an approximately 70% increase over untreated samples. MIP measurements confirmed the formation of a denser microstructure.