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Title |
Experimental Study for Evaluating Early Age Shrinkage of Mortar for 3D Printing
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Authors |
서은아(Eun-A Seo) ; 양근혁(Keun-Hyeok Yang) ; 이호재(Ho-Jae Lee) |
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DOI |
https://doi.org/10.11112/jksmi.2022.26.2.76 |
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Keywords |
3D 프린팅; 적층공법; 압축강도; 수축; 출력공정 3D printing; Additive manufacturing; Compressive strength; Shrinkage; Printing process |
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Abstract |
Since the 3D printing mortar is exposed to the atmosphere immediately after printing, moisture is largely evaporated from the surface of the layer. The evaporation of moisture on the surface of the layer greatly causes drying shrinkage and increases the risk of cracking and damage to the structure due to drying shrinkage. This study experimentally evaluated the shrinkage behavior of the initial age using the mortar used for 3D printing. The change in shrinkage was evaluated by comparing the shrinkage of the specimen cured by the sealing method and the atmospheric exposure method. In addition, compared with the case where type 1 cement was used 100%, the shrinkage amount was evaluated when 20% of fly ash was replaced and 10% of silica fume was used. In particular, the effect of three chemical admixtures applied using 3D printing on shrinkage was evaluated experimentally. When fly ash and silica fume were used, the shrinkage amount increased by 60 ? 110% compared to the case when type 1 cement was used. The application of viscosity modifiers and shrinkage reducers reduced the shrinkage by at least 18% and at most 70% depending on the curing conditions. The temperature of the specimen temporarily decreased to 15 ℃ at the beginning of curing, and the correlation between the internal temperature of the specimen and the shrinkage behavior was observed.
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