Document Type : Original Article
Authors
1
Ph.D. Candidate, School of Civil Engineering, Sharif University of Technology, Tehran, Iran
2
Associate Professor, School of Civil Engineering, University of Tehran, Tehran, Iran
3
Ph.D. Candidate, School of Civil Engineering, University of Tehran, Tehran, Iran
4
Assistant Professor, School of Civil Engineering, University of Tehran, Tehran, Iran
5
Ph.D., Institute of Structural Engineering, ETH Zurich, Zurich, Switzerland
6
Full Professor, School of Civil Engineering, University of Tehran, Tehran, Iran
7
M.Sc. graduate, School of Civil Engineering, Iran University of Science and Technology, Tehran, Iran
10.22065/jsce.2024.424406.3264
Abstract
3D printed concrete (3DPC) is a subset of additive manufacturing technology that has gained significant attention in recent years. However, one of the fundamental challenges of this technology is the shrinkage of 3DPC. The absence of formwork, low water-cement ratio, and fine aggregate characteristics pose critical challenges in the shrinkage of these types of concrete. Therefore, this article aims to reduce and control the shrinkage of 3DPC using an expansive admixture. Additionally, it evaluates the impact of the admixture on various concrete properties, including mechanical properties, fresh concrete properties, and 3DPC properties. In this study, five mix designs with expansive admixture proportions of 0.3%, 0.6%, 0.9%, 1.2%, and 1.5%, as well as one design without the admixture (the reference design), were selected for laboratory testing. The evaluation of free shrinkage for all six designs over a 177-day period indicates a 30% reduction in shrinkage when utilizing 1% of the expansive admixture. The direct relationship between mass loss and shrinkage in the tested specimens suggests that the majority of the measured shrinkage is attributable to water loss. The addition of 1% of the expansive admixture results in an 18% decrease in the compressive strength for the 7- and 28-day specimens, while each percentage increase in this admixture results in a 17% decrease in tensile (flexural) strength for the specimens at 28 days. Furthermore, each percentage increase in the use of this admixture in the six selected mix designs results in an 11% increase in the flow table test slump.
Keywords
Main Subjects
)