Effect of polyethylene fiber content on workability and mechanical-anisotropic properties of 3D printed ultra-high ductile concrete

Due to easy operation, quick construction and light weight, 3D concrete printing (3DCP) is expected as one of the potential solutions for future construction. This study is aimed to develop ultra-high ductile concrete (UHDC) with appropriate workability and use it as raw material for 3DCP. A series of experiments were carried out to study the effect of fiber content (1.0%, 1.5% and 2.0% by volume fraction) on workability and mechanical-anisotropic properties of the UHDC. Flowability and buildability tests results indicate that all the UHDC show acceptable workability in 3D printing. In uniaxial tensile test, the printed UHDC with higher fiber content exhibits slightly reduced tensile strength and strain capacity compared with the mold-cast ones except for UHDC with fiber content 1.0%. The results of compressive and flexural tests indicate the significant mechanical-anisotropic behaviors in failure patterns, compressive strength and flexural energy dissipation of the printed UHDC specimens. Comprehensively, the printed UHDC with fiber content 1.5% shows better performance in both workability and mechanical property, and at meantime possesses reduced material cost. Finally, two indexes were used to quantitatively evaluate the mechanical influence brought by printing process as well as mechanical anisotropy. (C) 2021 Elsevier Ltd. All rights reserved.