Author Contributions
Conceptualization, O.A. (Oded Amir), A.B., and O.A. (Ofer Asaf); methodology, O.A. (Ofer Asaf); software, O.A. (Oded Amir) and O.A. (Ofer Asaf); validation, A.B., P.L., E.M., and A.S.; formal analysis, O.A. (Ofer Asaf); investigation, O.A. (Ofer Asaf), O.Y.M., P.L., and E.M.; resources, P.L.; data curation, O.A. (Ofer Asaf); writing—original draft preparation, O.A. (Ofer Asaf), A.B., and O.A. (Oded Amir); writing—review and editing, A.S.; visualization, O.A. (Ofer Asaf), A.B., O.A. (Oded Amir), and O.Y.M.; supervision, A.B., O.A. (Oded Amir), and A.S.; project administration, P.L.; funding acquisition, A.B., O.A. (Oded Amir), and A.S. All authors have read and agreed to the published version of the manuscript.
Figure 1.
Framework for developing a holistic approach to optimize construction components produced by 3D printing with cementitious materials.
Figure 1.
Framework for developing a holistic approach to optimize construction components produced by 3D printing with cementitious materials.
Figure 2.
The geometry and post-tensioning scheme of the beam that was designed, fabricated, and tested to demonstrate the holistic approach.
Figure 2.
The geometry and post-tensioning scheme of the beam that was designed, fabricated, and tested to demonstrate the holistic approach.
Figure 3.
Particle size distribution of CEM I.
Figure 3.
Particle size distribution of CEM I.
Figure 4.
Particle size distribution of the two mineral admixtures used in this study.
Figure 4.
Particle size distribution of the two mineral admixtures used in this study.
Figure 5.
Strength build-up in mortar mixes formulated for 3D printing (
Table 1).
Figure 5.
Strength build-up in mortar mixes formulated for 3D printing (
Table 1).
Figure 6.
Development of static and dynamic yield stresses of the basic mortar mix designed for 3D printing.
Figure 6.
Development of static and dynamic yield stresses of the basic mortar mix designed for 3D printing.
Figure 7.
Dynamic modulus of elasticity curves obtained from ultrasonic testing during the first 60 minutes.
Figure 7.
Dynamic modulus of elasticity curves obtained from ultrasonic testing during the first 60 minutes.
Figure 8.
Relation between the dynamic modulus of elasticity and the static yield stress for the mortar mix in
Table 1.
Figure 8.
Relation between the dynamic modulus of elasticity and the static yield stress for the mortar mix in
Table 1.
Figure 9.
Effect of accelerators on the static and dynamic yield stress values.
Figure 9.
Effect of accelerators on the static and dynamic yield stress values.
Figure 10.
Dynamic modulus of elasticity curves from ultrasonic testing, showing the effect of accelerating admixture on a mix: (a) first hour; (b) first 10 hours.
Figure 10.
Dynamic modulus of elasticity curves from ultrasonic testing, showing the effect of accelerating admixture on a mix: (a) first hour; (b) first 10 hours.
Figure 11.
The effect of low-modulus fibers on the rheological behavior of the cementitious mix: black, red, green and blue for the mixes with 0.45%, 0.375%, 0.30% and 0% fiber content by volume for the static yield values, respectively; dashed blue line for the dynamic yield stresses which were practically independent of fiber content.
Figure 11.
The effect of low-modulus fibers on the rheological behavior of the cementitious mix: black, red, green and blue for the mixes with 0.45%, 0.375%, 0.30% and 0% fiber content by volume for the static yield values, respectively; dashed blue line for the dynamic yield stresses which were practically independent of fiber content.
Figure 12.
Effect of curing on the strength of the mix.
Figure 12.
Effect of curing on the strength of the mix.
Figure 13.
Schematic plot predicting plastic collapse during the printing process. The red line represents the cumulative stress due to self-weight on a single layer, while the black line indicates the material’s static yield stress value. If the cumulative stress surpasses the static yield value, plastic collapse is predicted, as shown by the intersection marked with a blue circle.
Figure 13.
Schematic plot predicting plastic collapse during the printing process. The red line represents the cumulative stress due to self-weight on a single layer, while the black line indicates the material’s static yield stress value. If the cumulative stress surpasses the static yield value, plastic collapse is predicted, as shown by the intersection marked with a blue circle.
Figure 14.
Linear functions fitted to the static yield evolution plots for a basic mortar mixture over the following three distinct time periods: 0 to 15 minutes, 15 to 30 minutes, and 30 minutes forward.
Figure 14.
Linear functions fitted to the static yield evolution plots for a basic mortar mixture over the following three distinct time periods: 0 to 15 minutes, 15 to 30 minutes, and 30 minutes forward.
Figure 15.
Stress evolution over time for a tapered cylinder with a bottom radius of 400 mm, a top radius of 100 mm, and a height of 1000 mm printed with a basic mortar mixture (density of 2130 kg/m3) using a layer height of 10 mm and layer width of 20 mm at a printing velocity of 150 mm/s. The colorful step plot shows the cumulative stress on each layer, indicating whether the layers are predicted to experience plastic collapse based on the material’s static yield stress.
Figure 15.
Stress evolution over time for a tapered cylinder with a bottom radius of 400 mm, a top radius of 100 mm, and a height of 1000 mm printed with a basic mortar mixture (density of 2130 kg/m3) using a layer height of 10 mm and layer width of 20 mm at a printing velocity of 150 mm/s. The colorful step plot shows the cumulative stress on each layer, indicating whether the layers are predicted to experience plastic collapse based on the material’s static yield stress.
Figure 16.
The 4-point bending setup of the beam to be optimized and manufactured.
Figure 16.
The 4-point bending setup of the beam to be optimized and manufactured.
Figure 17.
Shape optimization of the beam using spline parameterization of layer-wise cross sections. Left: initial design; Right: 2D view of the optimized design, showing all 100 cross sections. Each colored line represents a single layer.
Figure 17.
Shape optimization of the beam using spline parameterization of layer-wise cross sections. Left: initial design; Right: 2D view of the optimized design, showing all 100 cross sections. Each colored line represents a single layer.
Figure 18.
Shape optimization of the beam using spline parameterization of layer-wise cross sections. Three-dimensional view of the optimized design, showing all 100 cross sections in the intended printing position of each symmetric half of the beam.
Figure 18.
Shape optimization of the beam using spline parameterization of layer-wise cross sections. Three-dimensional view of the optimized design, showing all 100 cross sections in the intended printing position of each symmetric half of the beam.
Figure 19.
The digital blueprint production process at the intersection of material characteristics, processing parameters, and design optimization.
Figure 19.
The digital blueprint production process at the intersection of material characteristics, processing parameters, and design optimization.
Figure 20.
Step-by-step illustration of the digital blueprint production process for the designed half-beam curves. (a) Initial design of the half-beam curves; (b) creation of a smooth surface from the curves; (c) slicing the surface into the desired layer height; (d) placement of post-tensioning cables (in red); (e) iterative production of the infill pattern according to cable locations (in red); (f) visualized final 3D model.
Figure 20.
Step-by-step illustration of the digital blueprint production process for the designed half-beam curves. (a) Initial design of the half-beam curves; (b) creation of a smooth surface from the curves; (c) slicing the surface into the desired layer height; (d) placement of post-tensioning cables (in red); (e) iterative production of the infill pattern according to cable locations (in red); (f) visualized final 3D model.
Figure 21.
Plots of plastic collapse prediction of half-beam print path based on the material static yield evolution of the basic mortar mixture with varying printing velocities ((a) 70 mm/s; (b) 95 mm/s; (c) 120 mm/s). The black plot describes the material’s static yield stress as a function of elapsed time. The colored step plot describes the cumulative stress evolution in each printed layer.
Figure 21.
Plots of plastic collapse prediction of half-beam print path based on the material static yield evolution of the basic mortar mixture with varying printing velocities ((a) 70 mm/s; (b) 95 mm/s; (c) 120 mm/s). The black plot describes the material’s static yield stress as a function of elapsed time. The colored step plot describes the cumulative stress evolution in each printed layer.
Figure 22.
Illustration of the continuous printing path for the half-beams, showing the flipped printing direction of two alternating layers in two different colors, including the infill pattern.
Figure 22.
Illustration of the continuous printing path for the half-beams, showing the flipped printing direction of two alternating layers in two different colors, including the infill pattern.
Figure 23.
The 3D printing process of the first half-beam using a robotic cell setup.
Figure 23.
The 3D printing process of the first half-beam using a robotic cell setup.
Figure 24.
(Left) Printing the second half-beam. (Right) The completed half-beam, demonstrating a successful execution of the printing process over two consecutive days.
Figure 24.
(Left) Printing the second half-beam. (Right) The completed half-beam, demonstrating a successful execution of the printing process over two consecutive days.
Figure 25.
Geometric accuracy evaluation of the printed half-beams. The color maps show the deviation of the scanned half-beams from the computational model. The first half-beam (left) and the second half-beam (right) are displayed from both back and front views. The color scale represents the distance deviation in meters.
Figure 25.
Geometric accuracy evaluation of the printed half-beams. The color maps show the deviation of the scanned half-beams from the computational model. The first half-beam (left) and the second half-beam (right) are displayed from both back and front views. The color scale represents the distance deviation in meters.
Figure 26.
Optimized plots of layer stress buildup based on accelerator-enhanced mixtures’ static yield stress evolution with varying printing velocities ((a) 0% accelerator; (b) 1% accelerator; (c) 1.3% accelerator). The black plot describes the material’s static yield stress as a function of elapsed time. The colorful step plot shows the cumulative stress in each layer, indicating whether the layers are predicted to experience plastic collapse based on the material’s static yield stress.
Figure 26.
Optimized plots of layer stress buildup based on accelerator-enhanced mixtures’ static yield stress evolution with varying printing velocities ((a) 0% accelerator; (b) 1% accelerator; (c) 1.3% accelerator). The black plot describes the material’s static yield stress as a function of elapsed time. The colorful step plot shows the cumulative stress in each layer, indicating whether the layers are predicted to experience plastic collapse based on the material’s static yield stress.
Figure 27.
Optimized plots of layer stress buildup based on fiber-enhanced mixtures’ static yield stress evolution with varying printing velocities ((a) 0% fibers; (b) 0.3% fibers; (c) 0.375% fibers; (d) 0.45% fibers). The black plot describes the material’s static yield stress as a function of elapsed time. The colorful step plot shows the cumulative stress in each layer, indicating whether the layers are predicted to experience plastic collapse based on the material’s static yield stress.
Figure 27.
Optimized plots of layer stress buildup based on fiber-enhanced mixtures’ static yield stress evolution with varying printing velocities ((a) 0% fibers; (b) 0.3% fibers; (c) 0.375% fibers; (d) 0.45% fibers). The black plot describes the material’s static yield stress as a function of elapsed time. The colorful step plot shows the cumulative stress in each layer, indicating whether the layers are predicted to experience plastic collapse based on the material’s static yield stress.
Table 1.
Composition of the basic mortar mix for printing in units of kg per m3 of mortar.
Table 1.
Composition of the basic mortar mix for printing in units of kg per m3 of mortar.
Component | kg/m3 |
---|
Cement, CEM I | 459.3 |
Kaolinite clay | 98.5 |
Microsilica | 98.5 |
Sand | 1221.3 |
Water | 238.6 |
Polycarboxylate admixture (HTC 698) | 13.2 |
Unit weight | 2129.4 |
Table 2.
Mineralogical composition of Type I 52.5 cement.
Table 2.
Mineralogical composition of Type I 52.5 cement.
Compound | Weight% |
---|
C3S | 54.1 |
C2S | 19.55 |
C3A (Cubic) | 5.03 |
C3A (Ortho.) | 1.86 |
C3A (Total) | 6.89 |
C4AF | 12.17 |
CSH0.5 | 1.84 |
CH | 0.62 |
CC | 4.54 |
Aphthitalite | 0.59 |
Table 3.
Mineralogical composition of chocolate clay.
Table 3.
Mineralogical composition of chocolate clay.
Phase | Weight% |
---|
Kaolinite | 76.8 |
Quartz | 12.7 |
Calcite | 1.4 |
Ivsite | 3.9 |
Picromerite | 3.1 |
Orthoclase | 2.1 |
Table 4.
Statistical parameters of the cements and mineral admixtures used in this study.
Table 4.
Statistical parameters of the cements and mineral admixtures used in this study.
Admixture | Dx (10), μm | Dx (50), μm | Dx (90), μm |
---|
Chocolate clay | 3.15 | 17.1 | 42.4 |
Microsilica | 0.15 | 0.46 | 86.4 |
Table 5.
Half-beam manufacturing parameters.
Table 5.
Half-beam manufacturing parameters.
Print Path Length (m) | Layer Height (mm) | Layer Width (mm) | Printing Velocity (mm/s) | Printing Time (min) | Material Volume (L) |
---|
753 | 10 | 25 | 95 | 134 | 185 |
Table 6.
Printing statistics of optimized velocity with accelerator-enhanced mortar mixtures.
Table 6.
Printing statistics of optimized velocity with accelerator-enhanced mortar mixtures.
Mix Annotation | 0% Accelerator | 1% Accelerator | 1.3% Accelerator |
---|
Optimized printing velocity (mm/s) | 95 | 165 | 195 |
Printing time (min) | 134 | 77 | 65 |
Efficiency factor | 1 | 1.7 | 2.1 |
Table 7.
Printing statistics of optimized velocity with fiber-enhanced mortar mixtures.
Table 7.
Printing statistics of optimized velocity with fiber-enhanced mortar mixtures.
Mix Annotation | 0% Fibers | 0.3% Fibers | 0.375% Fibers | 0.45% Fibers |
---|
Optimized printing velocity (mm/s) | 95 | 140 | 155 | 230 |
Printing time (min) | 134 | 91 | 82 | 55 |
Efficiency factor | 1 | 1.5 | 1.6 | 2.4 |