Mechanical and environmental advantages of the revaluation of raw-crushed wind-turbine blades as a concrete component

Abstract

The large number of wind farms that will have to be dismantled in coming years is prompting a search for reliable wind-turbine-blade recycling methods, but there is not yet a broad consensus on the most appropriate. Jointly crushing all the blade components produces a material that is referred to as Raw-Crushed Wind-Turbine Blade (RCWTB), formed by fibers from the crushing of Glass Fiber-Reinforced Polymer (GFRP) composite, and spherical balsa-wood and polyurethane particles. The incorporation of this inexpensive and easy-to-produce material in concrete could help to solve the problem of blades recycling, but this approach has not been extensively evaluated in the literature. In the present study, the overall addition of RCWTB up to 6 % by volume in concrete was analyzed in terms of mechanical performance and carbon footprint. The results showed that the incorporation of RCWTB might be beneficial for both the mechanical behavior of concrete and its sustainability rating. RCWTB at 1.5 % improved compressive strength in a conventional concrete design, yielding values above 50 MPa at 28 days. Furthermore, this content reduced the carbon footprint per unit of compressive strength by 0.12 kgCO2eq/(MPa & sdot;m3). Similarly, 6.0 % RCWTB improved flexural strength, reaching values higher than 6 MPa, and reducing the carbon footprint per unit of flexural strength by 7.5 %. The waste had no significant negative effect on the temporal development of the mechanical performance of concrete. Furthermore, if all the wind-turbine blades annually dismantled in Spain, the world's fifth largest wind-energy producer, were crushed and converted into RCWTB, it could all be recycled at rates of 0.6-2.2 % within the total annual volume of commercial concrete produced in Spain. These figures show that RCWTB production is a feasible solution for recycling decommissioned windturbine blades, as it can be successfully used for manufacturing sustainable concretes with suitable mechanical and environmental performance levels.