Posted on March 24, 2022
3D printing using concrete or mortar formulations is also referred to as 3-Dimensional Concrete Printing (3DPC). Some refer to it as Building Additive Manufacturing (BAM). 3DPC involves extruding mortar or concrete through a nozzle, layer by layer. Advances in nozzle design allow for on-the-fly smoothing or texturing of walls.
Proponents say 3DPC is often faster, safer, cheaper and more efficient than some alternatives. There is also minimal waste. This is an important advantage when construction waste is a greater concern than ever.
Although 3D printing has gained a foothold in many industries, it remains a niche concept in most. In the concrete industry, will 3D printed structures ever go mainstream? Acceptance expanded in 2021.
3D Concrete Printing: From Novelty to Professional Acceptance
Recently, 3D concrete printing received a boost from the high cost of lumber. Also, new printer designs allow for larger projects. 3DPC is no longer for single-story, single-family dwellings alone. It is now used to build office structures and multi-story apartment buildings. Some hybrid projects blend 3D printed and traditional elements.
100 home development
In December 2021, Lennar Homes announced plans for a 100-home development using 3D printing. Home pricing in the Austin, TX, subdivision is commensurate with local median home prices. Lennar will use an ICON Vulcan printer to construct the first-floor walls. Lennar will still employ traditional construction methods to complete the upper floors.
ICON first displayed its first 3D-printed residences at Austin’s 2018 SXSW Festival. In 2021, its equipment printed seven homes at the city’s Community First Village.
The 9500-lb Vulcan prints to a height of 10.5 feet and a width of 36.5 feet. It extrudes a proprietary cementitious material called Lavacrete at five to 10 inches per second. ICON asserts that its printer can create resilient, single-story structures up to 3,000 sq ft in size.
If you’re thinking this new construction method is “out of this world,” it may turn out to be - literally. ICON is working with NASA on a construction system for creating structures on the Earth’s moon as well as Mars.
Long Island residence
The Autonomous Robotic Construction System (ARCS) is a 3DPC system from SQ4D. ARCS printed the walls and foundation of a 1,407 sq ft home on a quarter-acre lot in Riverhead, NY. The 3-bedroom, 2-bathroom residence is priced at $299,999. The builder completed the home using traditional siding and a shingled roof.
SQ4D’s 3D-printed structures come with a 50-year limited warranty. The company estimates construction costs are half those of local stick-built homes.
From homes to wind turbines
Danish firm COBOD introduced its BOD2 robot construction printer at WOC22. The BOD2 printhead glides along a metal frame. Three-axis printing allows for curved and complex shapes. The BOD2 will print 52 homes at a coastal development in Kenya. In December 2021, a 2,100 sq ft 3D printed home was unveiled in Muscat, Oman.
Importantly, COBOD is looking at additional applications. For example, it is collaborating with Holcim and GE Renewable Energy to print concrete bases for wind turbines. Onsite production allows for larger bases that support taller towers and larger blades. This allows for wind turbines capable of generating up to one-third more power.
3D Concrete Printing: Advantages
3DPC delivers a unique combination of automation, architectural freedom, resilience and simplified finishing.
Automation - Cobod’s BOD2 prints a ¾” x 2” layer at about three feet per second. One source estimates that “the walls of a small single-story house can now be constructed in as little as 12-24 hours.” More complex structures take a bit longer. According to ICON, each of the 1000-2000 sq ft homes on East 17th Street in Austin took 5-7 days to print.
Architectural freedom - 3DPC excels at delivering geometric complexity. A novel 3D printed castle is but one example. Aesthetically unique designs are easy to create.
Simplified finishing - Concrete walls have long enjoyed a key advantage — surfaces are often left “as is.” Consequently, It is possible to use the outside or inside of a 3D-printed wall without extra finishing. Painting or cladding are options as well.
Resilience - Of course, 3DPC structures must be compliant with building codes. A recent fire safety study looked at 3D-printed walls that met fire codes.
3D Concrete Printing: Challenges
3D printing with concrete comes with certain structural and other limitations. Also, transitioning to a different kind of workflow is not for everyone.
Cost of equipment - At present, the price of 3DPC machines ranges from about $200,000 to more than $1 million. However, at the high end of the scale, machines can cover more than 10,000 sq ft and print multiple floors. Nonetheless, such an investment requires a commitment to this construction specialty.
Will equipment costs come down due to the economies of scale or increased competition? Patents on equipment and proprietary cementitious formulations may limit competition to a degree.
Speed - Current equipment extrudes concrete at a modest pace. This is offset to a degree by a common advantage of industrial-grade robotics – tireless production.
Reliability - In many instances, 3DPC equipment has not been used for that long. Reliability is yet to be fully determined. For example, will clogging or maintenance needs inhibit productivity, and if so, by how much?
Structure size - For both structural and economic reasons, very tall buildings are not possible with current 3DPC technology. This challenge is offset to a degree by the ability to integrate this technology with traditional construction methods.
Future of 3D Concrete Printing
Questions remain as 3DPC seeks a foothold in residential and commercial construction.
To what degree will 3DPC challenge wood-frame construction?
How will the quest for sustainability impact its adoption?
At what pace will builders embrace this new construction method?
Will 3DPC remain a niche player, or will it go mainstream?
Freedom of design will attract architects. Curved walls and ready customization are key advantages. The low-cost construction of modest, yet resilient structures can address housing shortages.
The Pennsylvania Aggregates and Concrete Association (PACA) follows and reports on industry innovation. Our team welcomes your questions about your next concrete project. Please contact us at your convenience.