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

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.