Document Type : Original Article
Authors
1
Ph.D. Candidate, School of Civil Engineering, University of Tehran, Tehran, Iran
2
Associate Professor, School of Civil Engineering, University of Tehran, Tehran, Iran
3
Ph.D. Candidate, School of Civil Engineering, Sharif University of Technology, Tehran, Iran
4
Full Professor, School of Civil Engineering, University of Tehran, Tehran, Iran
5
Assistant Professor, School of Civil Engineering, University of Tehran, Tehran, Iran
6
Ph.D., Institute of Structural Engineering, ETH Zurich, Zurich, Switzerland
7
M.Sc. graduate, School of Civil Engineering, Iran University of Science and Technology, Tehran, Iran
10.22065/jsce.2024.424428.3265
Abstract
In recent years, the advantages of using 3D printed concrete (3DPC) have made it valuable for the construction industry. However, shrinkage is one of the basic challenges in the quality of printed concrete. Although the use of shrinkage reducing admixture is one of the methods to reduce the shrinkage of 3DPC, but there is still no relatively comprehensive research on the effect of additives, especially the shrinkage reducing admixture, on the characteristics of 3DPC and its shrinkage challenge. Therefore, in the present study, the effect of shrinkage reducing admixture on 3DPC properties was evaluated. In this regard, first, a suitable mixing plan without shrinkage reducing admixture was prepared for use in a 3DPC and as a control sample. Then, by using different percentages of shrinkage reducing admixture (0 to 2.5% of cement materials with 0.5% steps), suitable mixing plans are introduced in the 3DPC, and finally, mechanical and concrete properties are tested on all the samples. Recently, the test of free shrinkage and printing properties of 3DPC was done. According to the research results, the optimal amount of shrinkage reducing admixture is 2%. Also, the increase of the shrinkage reducing admixture caused a decrease in the compressive and bending resistance of the 3DPC, and the maximum decrease was about 13 percent in the compressive resistance and 6 percent in the bending resistance at the age of 28 days. All the designs showed good performance in constructability, printability and pumpability criteria. In addition, with the increase in the amount of shrinkage reducing admixture consumption, the mass loss decreased and the lowest mass loss was observed in the sample with 2.5% shrinkage reducing admixture.
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