Experimental study on anisotropic mechanical properties of 3D reinforced concrete with discrete polyethylene fibers

The mechanical properties of 3D-printed concrete, a key area of interest in civil engineering and materials science, are influenced by the loading orientation relative to the direction of the filament layer. This study investigates the mechanical behavior of 3D-printed reinforced concrete with discrete fibers—Polyethylene (PE) and High-Modulus Polyethylene (HPE)—under axial compression and flexural loading. Thirty-six printed and 21 molded specimens were analyzed to assess their flexural and compressive strengths, as well as the resulting cracking patterns that occurred. The results reveal that molded specimens exhibit greater strength than their printed counterparts. Additionally, strengths in the Z orientation exceed those in the Y orientation, with particularly pronounced differences observed in the Z direction. The optimal fiber content for PE and HPE reinforcement in printed concrete is determined to be 0.5%. This study enhances the understanding of fiber-reinforced concrete components and presents a comprehensive design framework that encompasses mix design, experimental procedures, and crack pattern analysis, focusing on both flexural and compressive strength.