Optimization of concrete containing wind-turbine wastes following mechanical, environmental and economic indicators

Abstract

The decommissioning of wind farms produces two primary waste materials: Recycled Concrete Aggregate (RCA) derived from the foundation concrete, and Raw-Crushed Wind-Turbine Blade (RCWTB) obtained through the crushing and sieving of the blades. Incorporating these materials into concrete enhances sustainability and, in some cases, improves mechanical properties while reducing the final environmental impact and cost compared to conventional concrete. A comprehensive characterization of the mechanical properties of concrete mixtures with varying RCA (0–100%) and RCWTB (0–10%) contents was conducted, these mixes being designed with increased water and admixture contents to compensate for the expected loss of workability caused by the addition of these waste materials. A Life-Cycle Assessment (LCA) and cost evaluation were also performed. The optimization of these mixtures was addressed using the Response Surface Method (RSM). The optimization process revealed that intermediate combinations of RCA (50%) and RCWTB (5%) yielded maximum flexural-tensile properties. However, achieving optimal performance proved more challenging when simultaneous optimization included compressive strength and deformability properties, such as modulus of elasticity and Poisson’s coefficient. For these properties, the optimal mix incorporated 88% RCA and 0% RCWTB. The RSM analysis demonstrated the feasibility of incorporating both RCA and RCWTB into concrete mixtures, mainly intended to work under bending stresses, but it also highlighted the complexities of achieving optimal performance when all mechanical properties were simultaneously considered. This research underscores the potential for these recycled materials to contribute to more sustainable concrete production while addressing the trade-offs in mechanical performance optimization.