Repurposing a Decommissioned Wind Turbine Blade for Bridge Construction: An Experimental Investigation

In structural recycling of wind turbine blades, two options are often distinguished: reuse and repurpose. The latter was the main subject of the present research carried out by the authors in a research consortium with the leading Polish industry waste recycler. The main goal of the project was to develop, design, and demonstrate the first domestic footbridge made of decommissioned wind turbine blades, taking into account the review of existing ideas. This paper presents an experimental investigation to determine the material parameters and to evaluate the structural behavior of a decommissioned wind turbine blade to be adopted for a footbridge. Terrestrial laser scanning and comprehensive material testing were performed according to ASTM standards to determine the actual blade geometry, the stacking sequence, and the mechanical properties of the blade composite materials. The experimentally determined strengths, elastic moduli, and Poisson’s ratios of the composites extracted from the shell and the spar cap along the blade were very high and definitely sufficient for the fiber-reinforced polymer bridge girders. Then, a four-point edgewise bending test was performed on an 11 m section of the blade to evaluate its structural behavior: stiffness, ultimate strength, global safety factor, and fatigue life. The full-scale model of the blade bridge girder behaved linearly elastic in the full load range up to 1,250 kN of the total load, did not reach the ultimate carrying capacity, and exhibited only small local damages (laminate cracking). The results of these tests revealed that the LM 29.1-type wind turbine blades were suitable to be reutilized as main girders for a footbridge. Using the presented research results, the first bridge in the world made of decommissioned wind turbine blades was designed and installed in the late fall of 2021 in Poland.