3D打印纤维再生细骨料混凝土孔隙结构与力学性能

Pore Structure and Mechanical Properties of 3D Printed Fiber-Reinforced Concrete with Recycled Aggregate

摘要:

3D打印纤维再生混凝土宏观力学性呈现显著的各向异性特征，与细观孔隙结构和层间界面区域存在密切相关。基于计算机断层扫描（CT）可视化分析3D打印混凝土试样可见，3D打印再生混凝土试样内孔隙呈椭球形定向分布。3D打印再生混凝土内孔隙平均紧密度显著低于浇筑试样，聚乙烯（PE）纤维和玄武岩纤维的掺入导致了紧密度均值的降低。同时，3D打印再生混凝土试样中孔隙长轴与Z轴在60°~90°夹角的孔隙占比高达58.0 %，远高于相同配合比的浇筑试样。纤维的掺入也对3D打印再生混凝土内部孔隙方向趋势产生了影响，PE纤维3D打印再生混凝土试样内垂直于Z轴的孔隙占比有所提高，玄武岩纤维试样内所占比例则有所降低。

Abstract:

The mechanical properties of 3D printed fiber-reinforced concrete with recycled aggregate show significant anisotropy， which is closely related to meso-pore structure and interface region. Based on the visualization analysis of 3D printing concrete samples by computed tomography(CT）， the porosity of 3D printed recycled concrete samples is ellipsoidal. The average pore compactness of 3D printed recycled concrete is significantly lower than that of mold-casted samples. The addition of polyethylene fiber and basalt fiber leads to the decrease of the mean compactness. Meanwhile， the ratio of pore length and Z-axis in 3D printed recycled concrete samples is as high as 58.0 % at orientations between 60°to 90°， which is much higher than that of mold-casted samples with the same mixture. Fiber addition also affects the pore orientation of 3D printed recycled concrete. The pore in the vertical to Z axis has increased for polyethylene fiber 3D printing recycled concrete specimens， while that has decreased for basalt fiber 3D printing recycled concrete specimens.