3D printing technology in building construction

3D printing technology in building construction

1. BY: Vodepalli Manaswini NITWarangal . 3D PRINTING TECHNOLOGY IN BUILDING CONSTRUCTION

2. CONTENTS Introduction Types Of 3D Printing Technologies In Construction Current Examples Framework For Laboratory Testing Of Printing Concrete In Fresh State Testing Procedures Advantages of 3D printing

3. Is it really possible to print a building…? And The Answer Is YES!

4. 3D CONCRETE PRINTING 3D concrete printing is an emerging technology that combines digital technologies and new insights from material technologies to allow free-form construction without the use of formwork. It is a type of additive manufacturing technique where the construction is through layer-by-layer addition of material.

5. It involves fabricating a predesigned building element in 2D layers on top of each other, the repetition of which results in a 3D model. The concrete, which is poured out of a printing nozzle, does not require any formwork or subsequent vibration

6. Two processes currently leading the 3DCP field are : The Extrusion based Single Deposition Nozzle Concrete Printer which is similar to fused deposition modeling. Contour Crafting is another technology where concrete is extruded against trowel; and Powder deposition process where the “ink” is deposited on a powder bed.

7. EXTRUSION-BASED 3D CONCRETE PRINTING The extrusion-based 3DCP is similar to the fused deposition modeling used in polymer and metal technologies. Contour crafting is one of the proprietary terminologies used for the layered fabrication technology It is based on extruding a cement-based concrete against a trowel that allows a smooth surface finish created through the build-up of subsequent layers

8. Current Examples of Extrusion-Based 3D Concrete Printing Elements/Structures (A) The two-story villa 3D printed by Huashang Tengda company; and (B) the novel nozzle of the giant 3D printer The frame of the house, including conventioinal steel reinforcements and plumbing pipes, were first erected Their giant 3D printer has a sort of forked nozzle that simultaneously lays concrete on both sides of the rebars , swallowing it up, and encasing it securely within the walls

9. The first 3D printed modular reinforced concrete beam of about 3 m The Y-Box Pavilion, 21st-century Cave 3 m tall structure

10. Onsite 3D printed house by Apis Core. (A) Construction using a mobile 3D concrete printer; (B) house exterior 3D printed bridge

11. POWDER-BED-BASED 3D CONCRETE PRINTING In the powder-bed process, a thin layer of powder is spread over the powder bed surface first. Once a layer is completed, binder droplets are selectively applied on the powder layer by a print-head causing powder particles to bind each other The binders are deposited only in places where the building material should become solid and the rest is kept loose and removed at a later stage. This uses D-shape 3D printing construction technology

12. Sculpture by D-shape process

13. FRAMEWORK FOR LABORATORY TESTING OF PRINTING CONCRETE IN FRESH STATE

14. MATERIALS THAT CAN BE USED

15. TESTING PROCEDURES In order to ensure that the achieved mix is the optimal one, several tests had to be conducted taking into consideration the target parameters to be achieved. The five parameters ( extrudability , flowability , buildability , compressive strength, and open time) together contribute to the success of the printing process.

16. Flowability Test Flowability could be defined as the ease with which concrete flows in a system under given conditions. Flow of each mixture can be determined using a flow table , which involves a mold being filled with mortar and then compacted. The mold is subsequently lifted away from mortar and the table is immediately dropped 25 times in 15 seconds. The flow is the resulting increase in average base diameter of the mortar mass expressed as a percentage of the original base diameter.

17. Flow value reduces upon addition of supplementary cementitious materials like silicafume and also with fiber reinforcement. A considerable increase in viscosity and cohesion of mixture will be observed because of a small addition of nanoclay

18. Print Quality “print quality” refers to the properties of a printed layer, such as surface quality and dimensional conformity/consistency, when using a specific printing mixture. A printing mixture could be considered acceptable when three requirements are satisfied: (1) The printed layer must be free of surface defects, including any discontinuity due to excessive stiffness and inadequate cohesion; (2) the layer edges must be visible and squared ( vs round edges); and (3) dimension conformity and dimension consistency must be satisfied by the printed layer. Based on these three proposed criteria, the print quality of a mixture can be evaluated and an acceptance decision can be made

19. Discontinuity (tearing) in the printed layer due to excessive stiffness of the mixture. (A) Variations in width of printed layer using different mixtures at the same printing speed (dimension conformity) (B) Variations in width of a single layer (dimension consistency).

20. Five measurements should done along each printed layer to assess the dimension conformity. Studies show that 10% error in the target width was a reasonable range for accepting or rejecting printed layers.

21. Shape Stability Three main sources of deformation which apply to a deposited layer: (1) self-weight; (2) weight of the following layer(s) to be printed on top of it; and (3) the extrusion pressure. Shape stability is a critical property of fresh concrete printing, which refers to the concrete’s ability to resist deformations during layerwise concrete construction Two different test methods, namely the layer settlement and cylinder stability tests, were developed and carried out to study the shape stability of printing concrete.

22. layer settlement test In this test, two concrete layers were printed on top of each other with a specific time gap photos were taken before and after the second layer was printed. A software was used to analyze the photos and to measure layer settlement. The average of five readings for a printed layer was reported as a test result. Studies show that shape stability of a printed layer improves over time

23. A five-layer printed specimen with interlayer time gap of 19 min .

24. cylinder stability test There are five steps in the cylinder stability test procedure: (1) the semicylinders are fixed in place and locked, and a concrete layer of 40 mm is placed; (2) using the tamping rod, the layer is consolidated by rodding 15 times and evenly distributed; (3) the same procedure is repeated for the second layer and excessive concrete is removed from the top A) 3D printed parts for cylinder stability test. (B) Cylinder stability test.

25. (4) the two semicylinders are unlocked and gently removed and any possible change in height as a result of self-weight is measured and recorded; (5) a load of 5.5 kg (equivalent to a 4.77 kPa stress) is applied and the resulting deformation in the fresh concrete cylinder is measured in terms of change in height. The main advantage of this test (compared to the layer settlement test) is eliminating the need to print concrete layers, leading to saving time during the mixture design phase.

26. Printability window Two important parameters related to the printability window include the printability limit and blockage limit. Printability limit is the longest period during which a mixture can be printed with acceptable print quality. Blockage limit refers to the longest period of time when a mixture can remain in the nozzle before the concrete hardens and blocks the extrusion.

27. Compressive Strength Test The concrete’s compressive strength is of particular importance due to the fact that the printing mechanism pours the structure in layers rather than in its entirety at once. Since the printing process happens only in a matter of minutes and setting time is assumed to be instantaneous, the targeted strength and strength gain should be high.

28. advantages When compared with conventional construction processes, the application of 3D printing techniques in concrete construction may offer excellent advantages including: Reduction of construction costs by eliminating formwork. Reduction of injury rates by eliminating dangerous jobs (e.g., working at heights), which would result in an increased level of safety in construction. Creation of high-end, technology-based jobs. Reduction of onsite construction time by operating at a constant rate. Minimizing the chance of errors by precise material deposition. Increasing sustainability in construction by reducing wastages of formwork. Increasing architectural freedom, which would enable more sophisticated designs for structural and esthetic purposes. Enabling the potential of multifunctionality for structural/architectural elements by taking advantage of the complex geometry

29. Contour Crafting was selected by NASA for its Innovative Advanced Concepts (NIAC) to explore the use of building a Lunar Settlement infrastructure

30. references Jay G. Sanjayan , Ali Nazari and Behzad Nematollahi , 3D Concrete Printing Technology , 2019.CHAPTER 2 :Performance-Based Testing of Portland Cement Concrete for Construction-Scale 3D Printing.  T.T. Le, S.A. Austin, S. Lim, R.A. Buswell , A.G.F. Gibb, T. Thorpe, Mix design and fresh properties for high-performance printing concrete, Material. Structure. 45 (8) (2012) 1221-1232. J. Pegna , Exploratory investigation of solid freeform construction, Automatic. Construction. 5 (5) (1997) 427-437. J. Zhang, B. Khoshnevis , Optimal machine operation planning for construction by contour crafting, Automatic. Constructio . 29 (2013) 50-67. A. Perrot, D. Rangeard , A. Pierre, Structural built-up of cement-based materials used for 3D-printing extrusion techniques, Material. Structure. 49 (4) (2016) 1213-1220. Apis Core, The first on-site house has been printed in Russia. On-line: http:// apis-cor.com/en/about/news/first-house., (accessed 20.03.17). F. Bos , R. Wolfs, Z. Ahmed, T. Salet , Additive manufacturing of concrete in construction: potentials and challenges of 3D concrete printing, Virtual Phys. Prototyping 11 (3) (2016) 209-225.