3D printing has come a long way over the past few decades, with the first iterations patented in the 1980s. Since then, the technology has evolved to be useful in a variety of industries including furniture, toys, tools, and more. But one of the most intriguing of the modern uses for 3D printing is construction. With its roots coming from a Rensselaer Polytechnic Institute project in New York in 1997, 3D concrete printing has been used now in a multitude of structures.
The technology works very similar to a traditional 3D printer. Designers will create a digital 3D model of the structure, wall, or component that will be built using modeling software. This is used to guide the printhead mounted on a gantry or robotic arm that lays down layers of the cement to create the final product. Unlike the 3D printers you may see in a school or home, 3D concrete printers are much larger, usually around 30 feet in height and length. When used for construction, these printers can be used on-site, meaning the structure is being printed where the building will be, or off-site, where printed parts will be shipped and assembled at the final location.
3D printing in construction has a few significant benefits. The first is decreased costs. A 2019 study analyzing the construction of military barracks huts compared the costs associated with 3D printed concrete, also referred to as additive construction, concrete masonry units, and reinforced concrete. While many of the supplies, equipment, and material were more expensive for the 3D-printed structures, costs were cut significantly due to lower labor costs. In fact, the cost of labor was 40-55 percent less than those of the traditional construction methods. The total cost of the additive construction was found to be 10-25 percent less than the concrete masonry unit and 25-37 percent less than the cast-in-place concrete.
Furthermore, a study published in the Applied Sciences journal in 2021 also examined the costs of 3D concrete printing compared to traditional construction methods. Here, they looked at the cost difference for round houses, where the 3D printed method costs half as much as traditional construction. These cost reductions can likely be attributed to the lack of formwork necessary for additive construction, often decreasing material and labor costs.
Another reason for lower labor costs from 3D printing is due to a benefit associated with the technology – quicker construction times. The same 2021 study also analyzed the difference in construction times for different construction methods. The study found that both on-site 3D concrete printing and off-site printing had faster construction times than traditional construction methods.
Given both the cost and time competitiveness of 3D concrete construction, why is it still so uncommon? The answer is likely regulation, as noted by the aforementioned paper. This is exacerbated by the fact that construction standards vary throughout the country based on state and county. However, the regulatory climate is beginning to change. Just this year, Montana became the first state to approve 3D-printed walls as a replacement for concrete masonry units. This was done in an effort to better meet rising housing demand while also cutting costs by a claimed 30 percent. If this trend continues, it may open up many opportunities for cheaper, more efficient construction.
Despite the regulatory difficulties, there have been a few examples of 3D-printed structures in the United States. The first owner-occupied printed structure was built in Virginia by Alquist 3D and Habitat for Humanity in 2021. More recently, the first net-zero 3D printed home was constructed by Mighty Buildings in September 2022, who claim its construction time was cut by more than half due to the technology.
Additive construction has also been used for smaller infrastructure projects around the world. Shanghai, China is home to the longest 3D-printed concrete pedestrian bridge in the world, measuring over 85 feet long. It was constructed by printing multiple units and assembling them at the bridge site. Even stainless steel has been used for 3D printing a bridge in Amsterdam, where robotic arms created the structure in a factory that was then placed by a crane in 2021.
This is just the tip of the iceberg for the potential uses for 3D printing in infrastructure. The technology could be used in a variety of facilities for construction or to repair existing infrastructure, such as roads. An ambitious project by Dr. Behrokh Khoshnevis of the University of Southern California to use 3D printing technology on Mars by the 2030s is receiving funding from NASA. The possibilities are nearly limitless and can have a significant impact on construction and infrastructure as the technology improves, especially given the proven cost-effectiveness of the practical applications.
Written by Andrew Barton, Public Policy Intern
The Alliance for Innovation and Infrastructure (Aii) is an independent, national research and educational organization. An innovative think tank, Aii explores the intersection of economics, law, and public policy in the areas of climate, damage prevention, energy, infrastructure, innovation, technology, and transportation.