Researchers at the University of New Mexico (UNM) have achieved a significant milestone in construction innovation by patenting a bendable concrete material designed for 3D printing.
UNM researchers have patented a bendable concrete material for 3D printing. Image: University of New Mexico.
Armed with a 3D concrete printer and advanced measuring tools, the team from the Gerald May Department of Civil, Construction, and Environmental Engineering is tackling long-standing challenges in construction and infrastructure maintenance.
The new material, self-reinforced ultra-ductile cementitious material, could pave the way for safer, more resilient buildings and bridges while significantly reducing the need for frequent repairs.
Rethinking traditional construction
Traditional construction methods often require heavy machinery and manual labour to position steel or wood beams, a process that is not only costly but also dangerous. Maryam Hojati, assistant professor at UNM, is leading efforts to automate and innovate this process with 3D printing.
Concrete, while strong in compression, is notoriously brittle under tension. This characteristic leads to frequent cracks and ongoing maintenance, whether for paths, buildings, or bridges.
“Concrete by itself does not show any tensile properties, meaning if you have a piece of concrete and start pulling it apart, it can easily break. It’s a very brittle material,” explains Hojati .
Natural disasters like earthquakes and high winds amplify the problem. These forces place tension on structures, further exposing concrete’s weaknesses. “The material should hold and resist both tension and compression. Concrete is a great material for compression, but when it comes to tension, it’s a weak material,” she adds.
Globally, researchers have been working to address these issues, but existing 3D printing techniques still rely on traditional reinforcements, such as beams or rebars, which limit the full automation potential of 3D printing.
The science behind bendable concrete
UNM researchers have developed a solution that addresses these limitations. PhD graduate Muhammad Saeed Zafar created a material blend that is both strong and flexible. “If we talk about 3D printing or additive manufacturing in the field of metals and plastics, it’s at a very advanced stage, but concrete printing is still developing,” notes Zafar.
The new substance integrates a high concentration of polymeric fibres, providing both tensile strength and flexibility. “Because of the incorporation of large quantities of short polymeric fibres in this material, it could hold all of the concrete together when subjected to any bending or tension load,” says Hojati.
The patented material, developed in collaboration with Zafar and researcher Amir Bakhshi, offers four distinct mixes, with strain capacities up to 11.9% higher than conventional materials. This blend maintains the necessary viscosity for smooth 3D printing without clogging the nozzle.
Achieving this balance was no easy feat. Testing involved printing small structures like prisms and dog bones, followed by rigorous evaluation of bending and tensile strength. Various materials were tested, including polyvinyl alcohol, silica fume, fly ash, and ultra-high molecular weight polyethylene fibres.
“The basic purpose of doing this work was to address the problem of reinforcement in 3D concrete printing,” explains Zafar. “We claim that 3D concrete printing is an automated process. But the conventional reinforcing methods are compromising the automation in this process.”
Paving the way for the future
The implications of this breakthrough extend far beyond Earth. Space agencies like Nasa are exploring 3D printing as a solution for constructing habitats on other planets. Transporting heavy steel beams and large workforces to space is impractical, making innovative materials like UNM’s bendable concrete a potential game-changer.
In the US, this technology could transform the construction industry by enabling structures that are more resilient to natural disasters and require less frequent maintenance. It also promotes greater automation, reducing costs and risks associated with traditional construction methods.
“This was very successful research. This material has 3D printing property and very high structural viability that could be used in the construction industry,” says Hojati.