Concrete is a popular material for 3D printing, especially in the construction sector. It’s a composite material of aggregate—usually geological materials such as gravel, sand and crushed rock—that is bonded by fluid cement and hardened over time. In recent years, it has become increasingly easy to use for additive manufacturing. Standard concrete 3D printers are like FDM printers, operating by material extrusion. However, concrete has a huge carbon footprint. According to Statista, manufacturing cement (which is part of concrete) produced 1.6 billion metric tons of carbon dioxide in 2022 alone. So, it’s great news that researchers developed concrete for 3D printing with low carbon emissions.
The concrete material for 3D printing that researchers at the Unviersity of Virginia developed has many promising characteristics: it’s strong, durable and emits significantly lower carbon emissions than traditional printable concrete mixtures. How did they achieve this? The researchers created a unique mix of graphene, limestone and calcined clay cement (LC2).
Osman Ozbulut, professor in the Department of Civil and Environmental Engineering. (Photo credits: Tom Daly via the University of Virginia)
Graphene, a carbon allotrope, is known for its strength and lightness. Osman Ozbulut, a professor at UVA’s Department of Civil and Environmental Engineering, explained, “The addition of graphene to LC2 cement offers a unique opportunity to lower carbon emissions while maintaining the strength and flexibility required for 3D printed construction.”
Their study, titled “Rheological, Mechanical, and Environmental Performance of Printable Graphene-Enhanced Cementitious Composites with Limestone and Calcined Clay,” was a deep dive into the novel material’s characteristics. Led by visiting scholar Tuğba Baytak and UVA’s Tawfeeq Gdeh, the team examined the material’s flow properties, mechanical performance and environmental impacts.
Understanding the Concrete’s Low Carbon Emissions
The team completed a life cycle assessment (LCA) to understand the material’s environmental impact. An LCA traces the energy usage needed to create a product, from beginning to end. This was completed by Zhangfan Jiang, a postdoctoral researcher at the Department of Civil and Environmental Engineering, in collaboration with Lisa Colosi Peterson, an environmental engineering professor at the University of Virginia. Remarkably, the two discovered that the graphene-enhanced LC2 concrete could reduce greenhouse gas emissions by about 31% compared to traditional printable concrete mixtures.
“Being able to see the full environmental footprint of this new concrete was important,” Jiang said. “It not only exhibits better mechanical performance but also has a lower environmental impact, making 3D concrete construction technology more sustainable compared to traditional 3D printing methods with higher carbon emissions.”
The Unversity of Virginia’s School of Engineering and Applied Science
Other collaborators on this project included researchers at the Virginia Transportation Research Council (VTRC), which allowed the UVA team to understand the material’s possible applications in the transportation industry. Ozbulut explained, “The VTRC collaboration was essential in uncovering the fundamental properties of this new concrete.”
Also notable, Tugba Baytak, a doctoral researcher from Istanbul Technical University, was part of the research team, and some of the funding came from The Scientific and Technological Research Council of Turkey (TUBITAK) along with funding from the University of Virginia’s 3 Cavaliers Program. Their research was published in the Journal of Building Engineering, 2024. For more, read UVA’s article here.
