Buildability and Mechanical Properties of 3D Printed Concrete

Abstract

Recently, 3D concrete printing has progressed rapidly in the construction industry. However, this technique still contains several factors that influence the buildability and mechanical properties of the printed concrete. Therefore, this study investigated the effects of the nozzle speed, the interlayer interval time, the rotations per minute (RPMs) of the screw in the 3D printing device, and the presence of lateral supports on the buildability of 3D concrete printing. In addition, this paper presents the results of the mechanical properties, including the compressive, splitting tensile, and flexural tensile strengths of 3D printed concrete. The buildability of 3D printed structures was improved with an extended interlayer interval time of up to 300 s. The printing processes were interrupted because of tearing of concrete filaments, which was related to excessive RPMs of the mixing screw. The test results also showed that a lateral support with a wide contact surface could improve the resistance to buckling failure for 3D printed structures. The test results of the mechanical properties of the 3D printed concrete specimens indicated that the compressive, splitting tensile, and flexural tensile strengths significantly depended on the bonding behavior at the interlayers of the printed specimens. In addition, although metal laths were expected to improve the tensile strength of the printed specimens, they adversely affected the tensile performance due to weak bonding between the reinforcements and concrete filaments.

Extrusion-Based 3D Printing of Ceramic Pastes: Mathematical Modeling and In Situ Shaping Retention Approach

“…This formulaic argument contributes to providing theoretical indications for reducing the blindness of experimental optimization. Furthermore, this work systematically provided a fully mathematical framework for the extrusion-based 3D-printing research community [ 51 , 52 ] from several realms: pastes rheology, extrudability, shape-holdability, and drying kinetics. Undoubtedly, this mathematical establishment provides a clearer and more reliable basis for extrusion-based process parameter optimization for ceramic pastes or other similar feedstocks [ 53 ].…”

Basic Experimental Evaluation of Fresh and Hardened Properties of Mortar Using Additive Manufacturing

“…본 연구에서는 소형 갠트리형 장비를 사용하여 적층 공법 을 적용하고, 경화 전⋅후의 모르타르 특성에 대한 기초 성능 평가를 수행하였다. 일정한 품질 유지를 위해 콘크리트 비빔시간에 따른 슬럼프 플로우의 변화를 통해 본 연구에서 사용된 배합의 최적 혼화제량 및 믹싱타임을 정량적으로 평가하였으며 (Roussel et al, 2005) (Le et al, 2012;Panda et al, 2017;Mechtcherine et al, 2019;Joh et al, 2020) (Roussel, 2018)…”

Cement Composites with Carbon‐Based Nanomaterials for 3D Concrete Printing Applications – A Review

“…[7][8][9][10] The printing performance is governed by the fresh characteristics of the concrete such as flow, viscosity, yield strength, and green strength and the printing parameters such as speed of nozzle and height, rate of extrusion, and interlayer interval time. [11,12] Thus, selecting suitable materials and mixing proportions is important to control the rheology, buildability, and printability with acceptable mechanical strength and durability of the 3D printable concrete.…”

“…The concrete materials and mixture design play a vital role in producing a high quality concrete or imparting the desirable characteristics to 3D printable concrete for example producing high performance, ultra‐high performance, lightweight, self‐healing, sustainable/eco‐friendly 3D printable concretes, and so on [7–10] . The printing performance is governed by the fresh characteristics of the concrete such as flow, viscosity, yield strength, and green strength and the printing parameters such as speed of nozzle and height, rate of extrusion, and interlayer interval time [11,12] . Thus, selecting suitable materials and mixing proportions is important to control the rheology, buildability, and printability with acceptable mechanical strength and durability of the 3D printable concrete.…”