Title: Reinforcing Interlayers of Three-Dimensional-Printed Mortar Using Metal Fiber Insertion

Author(s): Tomoya Nishiwaki, Yoshihiro Miyata, Shoko Furue, Shiko Fukatsu, and Hideyuki Kajita

Publication: Materials Journal

Volume: 118

Issue: 6

Appears on pages(s): 331-340

Keywords: cold joint; extrusion-based three-dimensional (3D) concrete printing (3DCP); insertion angle; interlayer; mechanical properties; reinforcing fibers; voids; X-ray computed tomography (CT)

DOI: 10.14359/51733133

Date: 11/1/2021

Abstract:
In recent years, various three-dimensional (3D) concrete printing (3DCP) systems have been developed extensively in the construction field. The extrusion-based 3DCP method using yield pseudoplastic mortar has emerged as the most promising system owing to its attractive properties. However, the poor bonding property of the interlayers brings cold joint-like gaps/voids, which decrease the mechanical properties of the printed elements. In this study, a novel reinforcing system was proposed for 3DCP-printed elements, in which metal fibers were inserted in the interlayers. Fundamental experiments were performed to verify the effectiveness of the proposed methods using different sizes and types of metal fibers. The results revealed that the tensile and flexural strengths of the printed elements improved when the reinforcing fibers were properly placed without air voids around the fibers. In addition, it was found that straight-shaped fibers were more suitable reinforcing fibers for avoiding voids.