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Title |
The Effects of Void Ratio on Extrudability and Buildability of Cement-based Composites Produced by 3D Printers
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Authors |
서지석(Ji-Seok Seo) ; 이봉춘(Bong-Chun Lee) ; 김윤용(Yun-Yong Kim) |
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DOI |
https://doi.org/10.11112/jksmi.2019.23.7.104 |
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Keywords |
3D 프린터; ME방식; 적층성; 출력성; 간극비 3D Printer; Material Extrusion; Buildability; Extrudability; Void Ratio |
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Abstract |
The material properties of the 3D printing cement composite mortar were evaluated, and the performance range in which printing was possible was calculated using the void ratio in a fresh state as a single index. As a results of the tests, as the water-binder ratio (W/B) increased, the mortar flow value increased and the density and strength decreased. As the sand-binder ratio (SS/B) increased, the mortar flow value decreased. However, strength and density increased and decreased up to a certain SS/B. As admixture-binder ratio (Ad/B) increased, mortar flow value, density, and strength decreased. These trends make it difficult to mix-design to meet the target performances of 3D printing mortars, represented by extrudability and buildability. The value of mortar flow increased proportionally with the void ratio, while the density and strength apparently decreased as the void ratio increased. This indicates that void ratio can be utilized as a single index for controlling the material properties in the design of mortar mixtures. It was found that mortar mixture could be printed by a 3D printer when the void ratio was in the range from 0.6 to 0.7. This was verified by printing a mortar which has the void ratio of 0.634. The mortar was produced with the mixture design of W/B 35.0%, SS/B 60.0%, and Ad/B 0.1%. Further research applying diverse admixtures is needed to improve the quality of 3D printing output mortars.
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