Date of Award

1-10-2024

Publication Type

Thesis

Degree Name

M.A.Sc.

Department

Civil and Environmental Engineering

Keywords

3DCP, cold joints, interlayer, mechanical properties

Supervisor

Sreekanta Das

Rights

info:eu-repo/semantics/openAccess

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Abstract

3D printing technology offers numerous advantages in construction, such as automation of the building process, the ability to create geometrically complex structures without the need for formwork. Also, this technology offers a significant reduction in labor and construction time, and a reduction in waste materials and energy. However, there are some challenges in using this technology in construction such as ensuring the quality of the applied material, weak interlayer interfaces, cold joints, anisotropic behaviors, durability, etc. The mechanical properties of the 3D printed cement mortar mixtures with fine aggregates were investigated by previous researchers. However, limited studies are available to determine the behaviour of the 3D printed concrete with coarse aggregates. In addition, only a few studies assessed the effect of cold joint in 3D printed cementitious structures, but the mechanical behaviour of cold joints is not investigated. This study examines the utilization of conventional concrete for 3D printing, incorporating smooth coarse aggregates of up to 10 mm in size extruded from the printer nozzle. The impact of using coarse aggregates on interlayer properties of 3D printed concrete with three different cold joint treatments is assessed. Furthermore, the mechanical performance of the cold joints is compared with regular interlayer and mold cast specimens. Also, the Ultrasonic Pulse Velocity (UPV) technique is used as a quality control instrument to evaluate the effectiveness of various cold joint treatments on the performance of 3D printed concrete. The results of experimental tests indicate that printed concrete material is anisotropic. The strength of 3D printed concrete in different directions depends on the various factors including printing pressure and presence of voids. Among three different cold joint treatments, cold joint specimens with concrete glue as bonding agent exhibited the highest material strength compared to other two cold joint treatments.

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