The large-scale retirement and high recycling difficulty of wind turbine blades (WTB) pose great challenges to environment and society. To explore the practical applicability of recycled WTB in 3D printed concrete (3DCP), a systematic experimental study was conducted on the printability and physical-mechanical properties of 3DCP incorporating RWTB fiber. The distribution of RWTB fiber and porosity were analyzed using X-ray CT scan and Scanning Electron Microscopy, with the aim of unveiling the reinforcing and anisotropic mechanisms of 3DCP with RWTB fiber. The concrete with 3%–7% of RWTB fiber presented good extrudability and buildability, although slightly decreased the fluidity. Due to the directional effect and the layer-by-layer stacking process inherent in 3D printing, the RWTB fiber exhibited enhanced alignment along the printing direction, leading to modifications in the porosity. Incorporating 5% RWTB fiber in 3DCP significantly improved mechanical properties, with notable increases of 13.2%–29.9% in unconfined compressive strength and up to 147.4%–465.4% in bending toughness in the Y and Z loading directions, as compared to samples without fiber. Moreover, the mechanical anisotropy of 3DCP with RWTB fiber was less significant than that with the fiber having higher tensile strength, leading to a promising way to repurpose WTB and promote sustainability of 3DCP.

中文翻译：

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风力涡轮机叶片回收纤维增强3D打印混凝土的实验研究

风力发电机叶片（WTB）的大规模报废和回收难度较高，给环境和社会带来了巨大挑战。为了探索再生WTB在3D打印混凝土（3DCP）中的实际应用性，对掺有RWTB纤维的3DCP的可打印性和物理机械性能进行了系统的实验研究。利用X射线CT扫描和扫描电子显微镜分析RWTB纤维的分布和孔隙率，旨在揭示RWTB纤维对3DCP的增强和各向异性机制。添加 3%~7% RWTB 纤维的混凝土表现出良好的可挤压性和可施工性，但流动性略有下降。由于3D打印固有的方向效应和逐层堆叠过程，RWTB纤维沿打印方向表现出增强的排列，导致孔隙率发生变化。与不含纤维的样品相比，在 3DCP 中加入 5% RWTB 纤维显着改善了机械性能，无侧限抗压强度显着提高了 13.2%–29.9%，Y 和 Z 载荷方向的弯曲韧性显着提高了 147.4%–465.4% 。此外，RWTB纤维的3DCP的机械各向异性不如具有较高拉伸强度的纤维的3DCP显着，这为重新利用WTB并促进3DCP的可持续性提供了一种有前途的方法。