The number one material used in the global construction industry is concrete. Concrete as a standalone material is very cheap, but the cost of creating of creating formwork makes it expensive. The formwork used to be a huge source of waste in the construction industry in the developed world, as it was all thrown away at some point during every construction project. Now, they are largely reusable except in third world countries. By some estimates, the construction industry is responsible for creating as much as 40 percent of the world's total waste.
Architects and designers are also constrained by the geometric limitations of casting concrete into formworks—unless they have the budget to have customized formworks created, which can be prohibitively expensive.
Can 3D printing solve these problems?
Problems with traditional construction methodology
The laundry list of complaints with the concrete construction industry is well known. Lead times are difficult to predict and control, there are persistent safety issues (worker injuries and deaths), issues with manufacturing formworks on job sites, issues with manufacturing offsite and issues transporting materials. These add up to a very slow, wasteful process which uses a huge amount of energy and is ecologically unsustainable.
In civil engineering, using precast procedures or casting in place at the jobsite are the preferred methods of creating structural members that will support a building, bridge or home in certain countries like Denmark, but differs depending on where you go. A variety of materials are used to create structures, but they always include concrete and masonry. Ordinary Portland Cement (OPC) is the main material for construction-grade concrete.
Engineers and architects have been working on experimental construction-grade additive manufacturing to explore ways to reduce the costs, lessen waste and improve the efficiency of legacy construction techniques. Rethinking techniques for creating structural members had led structural engineers, civil engineers and architects to explore different types of construction-scale 3D printing.
Construction-Scale 3D Printing
There are two methods of construction-scale 3D printing: extrusion gantry system printing and binder jetting. Binder jetting is also known as inkjet printing or binder printing. It works by depositing layer-by-layer a powder-based material and an activator to create a scaffold. This is the least commonly used 3D printing method for construction-scale projects and is based on the work on Enrico Dini, inventor of a construction-scale 3D printer called D-Shape.
D-Shape’s binder jetting 3D printing works like any other 3D printer, starting with a CAD file and slicer software. The digital slices are sent to the D-Shape printer, which is nestled in a 6m x 6m aluminum frame with a square base. The base travels upwards while printing, powered by a stepper motor on four vertical beams. The printer head has 300 nozzles spaced 20 mm apart. An aluminum beam connects the printer head to the base. The printer head deposits a layer of sand and magnesium oxide along the area enclosed by the frame.
Next, the printer head deposits an inorganic solution that contains magnesium chloride. This causes a chemical reaction, and within 24 hours, the material solidifies. There are gaps in the sand deposition due to the 20mm gaps between each of the 300 nozzles. A piston on the printer head’s beam moves the printer head perpendicularly back and forth four times to ensure an even distribution of sand. Then it repeats the process for each layer. The sand needs to be continuously refilled and the final product needs to be removed from excess sand that surrounds it, similar to the way industrial laser 3D printing post-processing methods.
Construction-Scale 3D Printing Around the World
Other construction-scale 3D printers use a similar cartesian robot, depositing various mixtures of cement and other materials. The more Portland cement a construction scale 3D printer uses, the more ecologically unfriendly it becomes.
This two-story building was recently completed in Dubai. This was printed by a special kind of robotic arm printer and took 11 months to print. The whole building took more than 1.5 years to complete and was done by EEC for the Dubai Municipality. This is not the first construction-scale 3D print for the region. 3D printed construction has been underway in the United Arab Emirates since Sheikh Mohammed bin Rashid, Vice President and Ruler of Dubai, opened a futuristic office for 3D printing technology outside Emirates Towers three years ago. (Image courtesy of Dubai Municipality.)
Denmark-based firm COBOD International manufactures construction-scale 3D printers. Pictured here is the company’s first-generation printer, the BOD, a gantry extrusion 3D printing system with an open-source mixture for layer-by-layer deposition. COBOD International signed a distribution agreement with organizations in Austria, Switzerland and Germany. (Image courtesy of COBOD.)
This home in Austin, Texas was 3D printed by the Vulcan, a signature extrusion printer from construction technologies company ICON. After getting the building permit from the city of Austin, the one-ton Vulcan is manned by a crew of five on average and has a massive footprint: 9 ft tall by 28 ft. wide. The material for this extrusion printer is a proprietary concrete mixture the company calls Lavacrete. The company recently announced the next edition of their 3D printer: the Vulcan II 3D printer. (Image courtesy of ICON.)
MudBots uses a mixture of lime, sand and cement to create large-scale prints. The prints include structural elements like pillars as well as the major construction of small homes using extrusion gantry system 3D printing. (Image courtesy of MudBots.)
The visualization you see here is called TECLA. The idea was conceived in a similar spirit to New Story by an organization called WASP, or World’s Advanced Saving Project. WASP was founded in 2012 by a group of architects who were inspired by the eco-friendly habitat building prowess of potter wasps. It’s currently being constructed in Bologna, Italy and is geometrically distinct from most other extrusion 3D printed shapes. It is built from recyclable and reusable materials (clay in this case) from the terrain immediately surrounding it, in an attempt to move the construction industry towards a more fundamentally sound ecological methodology. TECLA is the first 3D printed home to utilize a group of 3D printers. The material is a combination of locally sourced clays, which means it has virtually no waste when compared to traditional construction techniques. The project is so far incomplete. (Image courtesy of WASP.)
Bottom Line
Construction-scale 3D printing is often touted as a way to reduce the massive amount of waste generated by traditional construction methodology. As we approach 2020, it is clear that substantial progress has been achieved. The first permanent 3D printed building resides in Copenhagen, Denmark. It was built by COBOD International. It is similar to the 3D printed home printed by ICON in Austin, Texas, except the COBOD building in Copenhagen has proper permits for a permanent building status. ICON’s community center in Austin, Texas has received only temporary residence status by a local inspector.
Pictured above is the first residential building with 3D printed walls, located in Yaroslavl, Russia. It was built by SPECAVIA in December of 2015 and presented in October of 2017. No fewer than 600 separate elements of the walls were 3D printed in the company’s labs and were assembled on site. No building permit was obtained, nor was the building registered, but the residential building houses a family. This is one of only two 3D printed homes in the world at this time with a family living in it.
To reiterate, the gantry extrusion 3D printing technology at the core of all these projects was pioneered by Professor Berok Koshnehvis of UCLA. Enrico Dini’s D-Shape printer has yet to 3D print structural elements that are suitable for building a house that would pass code in Europe or America, where safety regulations are among the highest in the world. However, the D-Shape printer was used in conjunction with 3DBUILD technology developed by Spain-based ACCIONA.
This is the world’s first 3D printed bridge, built by ACCIONA with a D-Shape printer from Italian inventor Enrico Dini. It’s 1.75 meters wide and 12 meters long. (Image courtesy of ACCIONA.)
As a whole, construction-scale 3D printing remains largely experimental. It is not ready for primetime. Building and code regulations in developed countries are strict, and the construction-scale 3D printers that have created buildings and structures that pass muster are far and few between. There is a small building outside of a small hotel in Copenhagen, Denmark; a residential home with 3D printed elements in Russia and one in the YHNOVA house in France; and a public bridge in Spain. All were made using concrete in the mixture. But reductions to waste on the jobsites of these three projects were achieved. But these projects are good stepping stones into a more sustainable future. Progress is slow, but passionate pioneers can make all the difference.