Recycled Concrete Aggregate (RCA) and Raw-Crushed Wind-Turbine Blade (RCWTB) are waste materials obtained from decommissioned wind turbines after crushing their foundations and blades, respectively. Their use as raw materials in concrete allows their recycling. RCA increases concrete sustainability, while the fibers of Glass Fiber-Reinforced Polymer (GFRP) in RCWTB (66.8 % wt.) improve its bending performance. Nevertheless, only balanced waste combinations provide an adequate concrete behavior. Following a characterization of concrete in terms of fresh and strength performance, Response Surface Method (RSM) was conducted based on the experimental results to define the optimum waste combinations to reach a concrete strength performance adequate for engineering applications. RSM highlighted the need to limit the RCWTB content to 3 % to reach a compressive strength higher than 45 MPa, while amounts below 3 % and above 7 % would allow obtaining a flexural strength over 5.5 MPa. In both cases, the maximum content of coarse RCA should be 80 %. 70 % coarse RCA and a RCWTB amount between 6 % and 10 % would enable to develop concrete mixes with conventional strengths of 30–40 MPa under compression and 5 MPa under bending. RSM results revealed that RCWTB and their GFRP fibers properly behave in concrete with coarse RCA.
