Elsevier

Additive Manufacturing

Volume 37, January 2021, 101656
Additive Manufacturing

Experimental prediction of material deformation in large-scale additive manufacturing of concrete

https://doi.org/10.1016/j.addma.2020.101656Get rights and content

Highlights

  • Following experimental testing, deformation of printed concrete is encoded into a mathematical model that predicts layer width deformation.

  • Width deformation increases with the number of layers and beads, but the increment in deformation for each additional layer or bead decreases.

  • Following experimental testing, deformation of printed concrete is encoded into a mathematical model that predicts layer height deformation.

  • There is a time interval, 33.9 s, after which printed concrete deformation becomes zero.

Abstract

Additive manufacturing (AM) of cementitious material has become a popular subject over the last decade. The multidisciplinary nature of this topic has led researchers from multiple areas of expertise such as architecture, engineering, and materials science to collaborate to improve the technology, which does not permit yet to print mixtures with coarse aggregates, but is often referred to as AM of “concrete” or “concrete” printing. An important aspect of research in the area is finding a Portland cement-based mortar with adequate rheological, hardening and strength properties for printing architectural structures. In addition, the properties of fresh and hardened mortar and its deformation behavior affect the shape accuracy of the printed geometries and require designers to adjust the toolpaths and technology to account for issues in the printing. This paper is aimed at studying the deformation of a printed concrete mix, which previous studies have shown to be printable. It is focused on the effect of the number of layers, the number of beads and time on layer height and width. It proceeds through a series of experimental tests and it uses regression analysis to model material behavior. The resulting equations can be used in toolpath design to compensate for such deformation and have more accurate printed geometries subsequently. Future studies will be concerned with linking material properties with material deformation and use results to develop a more generic toolpath generator.

Section snippets

Introduction and motivation

Recently, using AM techniques in the building industry became more popular, as architects and engineers attempt to use their potential to build free-form, unsupported structures automatically. Even though AM technology in the building industry is in its early stage of adoption, it can be cost effective and time efficient while improving accuracy in construction [1]. These potential advantages have motivated many recent studies aimed at improving the technology, particularly, applied to

State of the art in large-scale additive manufacturing

In the architectural field of interest, AM has been used for concept modeling [10]. However, scaling up AM techniques for full-scale automated building construction can have a strong impact on the construction industry with increasing customization and design flexibility, reducing construction time, and reducing manpower and construction cost [11]. Although the use of AM for this purpose include experimentation with various materials such as plastic, metal, and clay [12], the focus of this

Printing material and printing system

The material used in all the experiments described in this study was developed by Gulf Concrete Technologies in cooperation with our research team. The mixture was a blend of Portland cement, lime, pulverized limestone, specially graded masonry sand, fibers and admixtures (Table 2). The maximum particle size in GCT concrete was 1 mm.

Mastersizer 3000 system, which applies laser diffraction technique was used to measure the particle size and particle size distribution of the GCT material. The

Experimental setup and methods

In this study three different set of experiment were conducted. Test 1 targeted the effect of the number of adjacent beads and layers on layer width deformation, Test 2 was aimed at finding the time interval after which the printed material stops deforming, and Test 3 studied the effect of different interlayer time intervals on layer height deformation.

Conclusions and future work

This study is part of a larger study whose goal is to study and model material deformation in construction scale additive manufacturing of concrete to compensate for such a deformation in toolpath design. For this purpose, a printing system consisting of a robotic arm and an industrial scale mixer and pump were used, together with a Portland cement-based concrete mix developed on purpose for 3D printing. Previous work addressed the effect of printing orientation and direction and the number of

CRediT authorship contribution statement

The paper study the effect of time, the number of beads and the number of layers on deformation of a printed concrete mix. Negar is the PhD student who carried out the research, advised by J. Duarte in design computing, S. Nazarian in material matters, and N. Meisel in engineering design.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This research was financially sponsored by The Raymond A. Bowers Program for Excellence in Design and Construction of the Built Environment, The Pennsylvania State University, Autodesk, Inc. ®, and Golf Concrete Technology (GCT). The authors express their gratitude to Dr. Sven Bilén, Dr. Ali Memari, Dr. Aleksandra Radlińska, Mr. Jamie Heilman, Mr Zhanzhao Li, and Mr. Nathan Watson, for their valuable insights and contributions to this research.

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