• Korean Journal of Construction Engineering and Management
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• v.23 no.1
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• pp.113-117
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• 2022

Additive manufacturing (AM, also known as 3D printing) technology is digitalized technology, making it easy to predict and manage quality and also, have design freedom ability. With these advantages, AM technology is applied to various industries. In particular, a method of manufacturing buildings and infrastructure with AM technology is being proposed to the construction industry. However, the application of AM technology is restricted due to problems such as insufficient history and quality of technology, lack of construction management methods, and certification of manufacturing products. Therefore, the manufacture of architectural products is implemented with indirect AM technology. In particular, it manufactures formwork using AM and injecting building materials to implement the architectural product. In this study, hybrid type material extrusion AM is used to manufacture large-sized formwork and implement building products. Moreover, we identify factors that can predict productivity and economic feasibility in the additive manufacturing process. As a result, design optimization results are proposed to reduce the production cost and time of architecture buildings.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.1
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• pp.24-31
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• 2024

Mortar has been applied in most previous studies on 3D concrete printing. In such cases, however, the economic efficient cannot help decreasing due to higher binder contents and larger amount of fine aggregates. In order to enhance the applicability of 3D printing technology to construction industry, therefore, 3D concrete printing technology utilizing coarse aggregates needs to be developed further. This study aims at proposing the mix design process of concrete containing coarse aggregates for 3D printing. Based on extensive literature review and experimental studies, the mix proportion suitable for 3D printing has been derived, and the extrudability of concrete with coarse aggregates has been verified through 3D printing tests. The primary variable of the extrudability tests was the contents of viscosity modifying agent (VMA), and the extrudability was quantitatively evaluated by measuring dimensions, distribution of aggregates, and surface quality of 3D-printed filaments. The test results showed that the dimensional suitability and surface quality were improved as the VMA contents were larger, and the coarse aggregates were evenly distributed in the section of filament regardless of the VMA contents. Based on the test results, the mix design process for concrete containing coarse aggregates for 3D printing has been proposed.

• Journal of the Korean Geotechnical Society
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• v.40 no.2
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• pp.81-93
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• 2024

In Korea, numerous large-scale infrastructure construction projects and housing site developments are being undertaken. However, due to limited land availability, sourcing high-quality backfill materials that meet the standards for railroad and road embankment compaction and mechanically stabilized earth (MSE) retaining wall construction poses significant challenges. Concurrently, there has been an increase in structural failures of many MSE retaining walls, attributed primarily to reduced bearing capacity and impaired drainage performance, resulting from inadequate backfill compaction. This study aimed to analyze the structural performance and safety of an MSE retaining wall using recycled soil as backfill. We conducted small-scale model tests utilizing 3D printing technology combined with two-dimensional numerical analysis. The study quantitatively evaluated the MSE retaining wall's performance concerning the recycled soil mixing ratio and reinforcement installation methods. Furthermore, the utility of 3D printing was confirmed through the production of an experimental wall designed to facilitate easy reinforcement attachment, mirroring the conditions of actual MSE retaining wall construction.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.11
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• pp.3-10
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• 2018

Cladding that finishes the exterior of a building could enhance the value of the building, and shape control is an important factor. With the recent development of 3D printing, cementitious claddings were printed by 3D printer in China, U.S.A and elsewhere. On the other hand, the structural safety of the exterior panel should be examined, as casualties occur when the exterior panel fails due to typhoon or impact. Cement-based cladding is reinforced by wire mesh to improve safety. Introducing 3D printing composite system with polymer and cement, makes it possible to produce claddings fast and accurate. Prior to the development of 3D printing cementitious cladding, the major parameters influencing the optimal shape were identified based on structural performance. The wind load, joint, and bond behavior between polymer and cement were considered. Polymer laminate shape, order, and thickness were variables, and finite element analysis was performed.

• Journal of Information Processing Systems
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• v.18 no.2
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• pp.223-234
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• 2022

The evaluation of the print quality of 3D printing has traditionally relied on manual work using dimensional measurements. However, the dimensional measurement method has an error value that depends on the person who measures it. Therefore, we propose the design of a new print quality measurement method that can be automatically measured using the field-of-view (FOV) model and the intersection over union (IoU) technique. First, the height information of the modeling is acquired from a camera; the output is measured by a sensor; and the images of the top and isometric views are acquired from the FOV model. The height information calculates the height ratio by calculating the percentage of modeling and output, and compares the 2D contour of the object on the image using the FOV model. The contour of the object is obtained from the image for 2D contour comparison and the IoU is calculated by comparing the areas of the contour regions. The accuracy of the automated measurement technique for determining, which derives the print quality value was calculated by averaging the IoU value corrected by the measurement error and the height ratio value.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.4
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• pp.227-233
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• 2022

The 3D-printing technique is used for manufacturing objects by adding multiple layers, and it is relatively easy to manufacture objects with complex shapes. The 3D concrete printing technique, which incorporates 3D printing into the construction industry, does not use a formwork when placing concrete, and it requires less workload and labor, so economical construction is possible. However, 3D-printed concrete is expected to have a lower strength than that of molded concrete. In this study, the properties of 3D-printed concrete were analyzed. To fabricate the 3D-printed concrete samples, the extrusion path and shape of the samples were designed with Ultimaker Cura. Based on this, G-codes were generated to control the 3D printer. The optimal concrete mixing proportion was selected considering such factors as extrudability and buildability. Molded samples with the same dimensions were also fabricated for comparative analysis. The properties of each sample were measured through a three-point bending test and uniaxial compression test, and a comparative analysis was performed.

• Journal of the Korea Institute of Building Construction
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• v.20 no.2
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• pp.171-181
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• 2020

Recently, free-formed construction technology is becoming a new measure of representing technological superiority and sociocultural ingenuity. However, the CNC processing technology utilizing the existing wood and iron form has limitations in terms of the manufacturing time and material cost. Therefore, in this study, the method and process of manufacturing free-formed EPS form using S-LOM-based 3D printing technology were suggested. Furthermore, through the mock-up test, a comparative analysis of the manufacturing time and precision with CNC milling technology was conducted. The results show that S-LOM-based 3D printing technology has reduced manufacturing time about 57.4% compared to CNC milling technology during the free-formed EPS form manufacturing process. In addition, compared to the design drawings, the maximum error value was 20.5mm, proving the applicability of S-LOM-based 3D printing technology. The results of this study are expected to contribute to the improvement of S-LOM method and the activation of S-LOM method by verifying the applicability of S-LOM-based 3D printing technology.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.154-155
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• 2021

Appearance finish is important for amorphous buildings to maximize amorphousness, and GFRC, glass, and metal are mostly used as exterior materials for amorphous buildings currently applied. However, the existing exterior materials showed limitations in amorphous expression, texture, and color expression. In this study, a 3D stereoscopic panel mold was manufactured using the FDM method, one of the 3D printing technologies, and 3D stereoscopic panel production was reviewed using Ultra High Performance Concrete (UHPC), which has excellent physical and mechanical performance and expression. In order to overcome the limitations of unstructured expression, a UHPC 3D stereoscopic panel using the FDM method, one of the 3D printing technologies, was manufactured. Unlike steel molds, FRP molds, and EPS molds, the FDM method can be applied to various materials, and complex shapes are implemented. If it is used using recyclable materials as well as PLA filaments used in the FDM method, it will overcome the limitations of amorphous expression and activate the production of 3D stereoscopic panels that have secured eco-friendliness.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.3
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• pp.174-181
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• 2018

This paper examines the structural behavior of 3D printed concrete specimens with focus on the bond between the layers. The tensile bond and flexural strengths were investigated experimentally and compared with those of specimens made by conventional mold casting. The test parameters were the time gap between printing layers and the reinforcement between vertical layers. The results showed the 3D printed specimens had voids between layers and confirmed the strength reduction due to printing time gap and the stress concentration caused by the voids. Most of the reduction in tensile bond strength between layers was due to the stress concentration at least up to certain printing time gap. Moreover, beyond a certain printing time gap (24hours), the additional reduction in tensile bond strength reached a level that could affect the structural behavior. The reinforcement between layers was helpful to increase the ductile behavior which is essential to prevent the sudden collapse of the structure. In addition, the reduction in flexural strength due to the stress concentration by the voids was observed and should be considered in the design of 3D printed wall structures against the lateral load.

• Journal of Drive and Control
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• v.16 no.3
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• pp.51-58
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• 2019

The objective of this study was to investigate a simulation technology for the AM field based on ANSYS Inc.. The introduction of metal 3D printing AM process, and the examining of the present status of AM process simulation software, and the AM process simulation processor were done in the previous study (part 1). This present study (part 2) examined the use of the AM process simulation processor, presented in Part 1, through direct execution of Topology Optimization, Ansys Workbench, Additive Print and Additive Science. Topology Optimization can optimize additive geometry to reduce mass while maintaining strength for AM products. This can reduce the amount of material required for additive and significantly reduce additive build time. Ansys Workbench and Additive Print simulate the build process in the AM process and optimize various process variables (printing parameters and supporter composition), which will enable the AM to predict the problems that may occur during the build process, and can also be used to predict and correct deformations in geometry. Additive Science can simulate the material to find the material characteristic before the AM process simulation or build-up. This can be done by combining specimen preparation, measurement, and simulation for material measurements to find the exact material characteristics. This study will enable the understanding of the general process of AM simulation more easily. Furthermore, it will be of great help to a reader who wants to experience and appreciate AM simulation for the first time.