Enhancing 3D-Printed Cementitious Composites with Recycled Carbon Fibers from Wind Turbine Blades (2025-03)¶

Incorporating waste fibers, such as those from recycled plastics or agricultural byproducts, reduces the environmental impact by diverting waste from landfills and lowering the carbon footprint of concrete production. In this paper, we are investigating the utilization of carbon fibers sourced from decommissioned wind turbine blades to create stronger and greener cement paste mixes targeting the enhanced tensile strength. We are proposing to align the carbon fibers along the direction of the mechanical stress generated by the interaction of the 3D printing (3DP) nozzle geometry and the pumped cementitious matrix. A series of three-point bending and compression tests are conducted on 3D-printed specimens produced under different nozzle geometries, and the flexural modulus and compressive strength of specimens are examined to understand the anisotropic mechanical behavior of the extruded materials. We demonstrate the application by 3DP and testing small-scale specimens with aligned fibers and compare performance against specimens with randomly distributed fibers and controls (specimens without fibers). Results show that incorporating 2wt% of carbon fibers significantly improves the flexural and compressive strengths of 3D-printed specimens respectively by 74.6% and 34.5% when compared to 3D-printed plain cement paste, and respectively by 71.63% and 22.72% when compared to mold-cast plain cement paste.