Book chapter · Conference paper
Influence of Processing Parameters on the Layer Geometry in 3D Concrete Printing: Experiments and Modelling
Manufacturing Engineering, Department of Mechanical Engineering, Technical University of Denmark1
Department of Mechanical Engineering, Technical University of Denmark2
Technical University of Denmark3
Danish Technological Institute4
Department of Civil Engineering, Technical University of Denmark5
Structures and Safety, Department of Civil Engineering, Technical University of Denmark6
This paper presents the numerical simulation results of a computational fluid dynamics (CFD) model that describes the layer shape in extrusion-based 3D Concrete Printing (3DCP). The simulation outcome is validated through an experimental program in which we investigated the influence of 3DCP processing parameters on the geometry of a single layer.
Specifically, a set of single layers were printed using a Ø25 mm nozzle mounted on an 6-axis industrial robotic arm travelling at different speeds and with different layer heights. A fresh concrete -- comprising CEM I 52,5 R - SR 5 (EA), limestone filler, fine sand, water, and admixtures (i.e. viscosity modifying agent, high-range water-reducing admixtures and a hydration retarder) -- was pumped and extruded at a fixed volumetric rate.
Once hardened, the extruded layers were sliced to examine the resulting cross-sections. Specifically, the cross-sections' geometry were obtained by a custom image processing algorithm. Next, the extrusion flow was modelled with a CFD simulation using the software FLOW-3D®. The constitutive behavior of fresh concrete was modelled as a Bingham fluid, while the volume-of-fluid method was used to predict the free surface of the concrete and, thus, the layer geometry.
The numerical results agree qualitatively with the experimental observations, enabling us to identify two non-dimensional 3DCP processing parameters that influence the overall cross-sectional shapes: 1) the geometric ratio between layer height and nozzle diameter, and 2) the ratio between the nozzle velocity and the extrusion volumetric flux.
These findings -- when complemented with a model describing the overall deformation of stacked layers -- serve as the basis for correlating material rheological properties to 3DCP process parameters, promoting a better link between design and fabrication in a 3DCP context.
Language: | English |
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Publisher: | Springer |
Year: | 2020 |
Pages: | 852-862 |
Proceedings: | 2nd RILEM International Conference on Concrete and Digital Fabrication |
Series: | R I L E M Bookseries |
Journal subtitle: | Digital Concrete 2020 |
ISBN: | 3030499154 , 3030499162 , 9783030499150 and 9783030499167 |
ISSN: | 22110844 |
Types: | Book chapter and Conference paper |
DOI: | 10.1007/978-3-030-49916-7_83 |
ORCIDs: | Comminal, Raphael , Stang, Henrik , Spangenberg, Jon and 0000-0001-9895-5128 |