A research team from the University of Virginia School of Engineering and Applied Science has been the first to investigate how a novel plant-based material, cellulose nanofibrils, could enhance the benefits of 3D-printed concrete technology.
“The improvements we saw on both printability and mechanical measures suggest that incorporating cellulose nanofibrils in commercial printable materials could lead to more resilient and eco-friendly construction practices sooner rather than later,” said Osman E. Ozbulut, a professor in the Department of Civil and Environmental Engineering.
3D printing of concrete is an emerging trend in construction that offers numerous benefits: fast and precise construction, potentially from recycled materials, reduced labor costs and waste, and the ability to create complex designs that would be difficult to implement using traditional methods. The process uses a special printer that applies a cement-like mixture in layers to create the structure using CAD software. So far, however, the available printable materials are limited and questions about sustainability and durability remain.
“We’re dealing with contradictory objectives,” Ozbulut said. “The mixture has to flow well for smooth fabrication, but harden into a stable material with critical properties, such as good mechanical strength, interlayer bonding and low thermal conductivity.”
By experimenting with different amounts of CNF additive, the team found that adding at least 0.3% CNF significantly improved the flow properties. Microscopic analysis of the cured samples showed better material bonding and structural integrity. Further tests in Ozbulut’s laboratory showed that CNF-reinforced 3D-printed components also withstood tensile, flexural and compressive loads.
“Today, a lot of trial and error goes into designing mixtures,” he said. “We’re addressing the need for more good science to better understand the effects of different additives to improve the performance of 3D-printed structures.”
This research could significantly improve the acceptance and application of 3D-printed concrete in the construction industry and open up new avenues for more sustainable and efficient construction methods.
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