The University of New Mexico (UNM) has announced a significant advancement in 3D printing technology with the development of bendable concrete. The material, which promises to revolutionize construction, is now patented.
Researchers at the Gerald May Department of Civil, Construction, and Environmental Engineering have focused on creating materials for 3D printing concrete structures. Assistant Professor Maryam Hojati aims to address challenges in traditional construction, which often involves heavy machinery and costly processes.
"Concrete by itself does not show any tensile properties," said Hojati. "It’s a very brittle material." This brittleness can lead to infrastructure issues like cracks in sidewalks, necessitating frequent repairs.
Natural disasters pose additional challenges due to concrete's weakness under tension. "The material should hold and resist both tension and compression," explained Hojati.
Graduate research assistant Muhammad Saeed Zafar developed a promising substance during his Ph.D. studies. "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," he noted.
The patented substance, known as self-reinforced ultra-ductile cementitious material, was registered last August by UNM Rainforest Innovations. It involved contributions from Zafar and Amir Bakhshi, another research assistant involved early in the project.
"The basic purpose of doing this work was to address the problem of reinforcement in 3D concrete printing," stated Zafar. He highlighted that conventional reinforcing methods hinder automation in this process.
Achieving the right balance of fiber content is crucial for the material's effectiveness. Too little fiber may cause printed shapes to collapse; too much could clog the printer nozzle. The researchers meticulously tested various mixes for their bending and tensile strength capabilities.
"Because of the incorporation of large quantities of short polymeric fibers in this material, it could hold all of the concrete together when subjected to any bending or tension load," Hojati explained.
Funding from grants provided by the Transportation Consortium of South-Central States (Tran-SET) supported three related research projects at UNM: developing a 3D printable engineered cementitious material, evaluating its properties in fresh and hardened states, and creating a 3D printable eco-concrete.
In addition to terrestrial applications, there are potential benefits for space exploration where traditional construction methods are impractical due to weight constraints. NASA is exploring alternative methods involving bots equipped with 3D printers for planetary construction tasks—a challenge that Hojati's team is also addressing through various projects.
"This was very successful research," said Hojati. "This material has 3D printing property and very high structural viability that could be used in the construction industry."
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