Preparing Geopolymers Using Waste Wind Turbine Blade Powders: Mechanical Activation of Glass Fiber–Reinforced Polymer and Its Effects

Abstract With global wind power capacity exceeding 1.021 billion kW, decommissioned carbon/glass fiber blades create a major disposal challenge. This study aims to effectively dispose of and utilize discarded wind turbine blades by developing a technology for preparing geopolymers using blade glass fiber–reinforced polymer (GFRP) as a raw material, and to investigate mechanical activation methods for enhancing the reactivity of the GFRP. The effects of ball-milling speed, ball-milling time, and alkali activators on the particle size of the GFRP powder, pozzolanic activity, and properties of the reaction products are investigated. The results confirmed that the particle size of the GFRP powder decreases with an increase in the ball-milling speed and milling time, and the particle-size distribution becomes narrower in this case. The GFRP undergoes a geopolymerization reaction to form a hardened paste under the action of alkali activators. The smaller the particle size of the GFRP, the higher the compressive strength of the geopolymer. The compressive strength of the GFRP geopolymer initially increases and subsequently decreases when the modulus of the alkali activator increases from 1.0 to 1.8, and the water-to-binder ratio rises from 0.33 to 0.42. However, the strength of the GFRP geopolymer consistently increased with an increase in alkali content in the paste. The ball-milled GFRP-based geopolymer specimens with a size of 20 × 20 × 20 mm 3 exhibited a 28-day compressive strength of 42.1 MPa, which is three times that of their non-ball-milled counterparts. The potential application of the GFRP-based geopolymer could be the prefabricated components, such as drainage pipes and bricks. This significant enhancement in mechanical properties was achieved with a grinding energy consumption of approximately 1,125 kWh per ton of GFRP. Furthermore, the resulting geopolymer has a carbon footprint of about 1, 392.99 kg · CO 2 - e / m 3 , substantially lower than the 1,800 kg · CO 2 - e / m 3 associated with traditional cement.