Researchers at Nanyang Technological University in Singapore (NTU Singapore) have developed a new 3D concrete printing technique that captures carbon, introducing a novel approach to reducing the environmental impact of the construction industry.
This groundbreaking technique aims to significantly reduce the carbon footprint of cement – a substance that contributes 1.6 billion tonnes of carbon dioxide (CO).2) or about eight percent of global CO2 Emissions – due to lower material consumption, shortened construction times and lower labor costs.
The new 3D concrete printing process uses steam and CO2which are collected as by-products from industrial activities, directly into the mixed concrete. This not only saves CO2 in concrete construction, but also minimizes material consumption, shortens construction time and reduces workload. Studies show that this method improves the mechanical properties of concrete and provides greater strength than traditional 3D printed concrete.
“The construction sector causes a significant proportion of global greenhouse gas emissions” said Professor Tan Ming Jen, principal investigator of the study. “Our newly developed 3D concrete printing system offers a CO2-reducing alternative by not only improving the mechanical properties of concrete, but also helping to reduce the sector’s environmental impact. It shows the possibility of using CO2 manufactured by power plants or other industries for 3D concrete printing. Since conventional cement emits a lot of carbon, our method offers a way to push back CO2 through 3D concrete printing.”
The research team believes their innovation represents a promising contribution to achieving global sustainable development goals and reducing the industry's dependence on traditional energy-intensive processes such as reinforced concrete construction.
The new development builds on previous 3D printing for construction research by Prof. Tan and his team at NTU's SC3DP, as well as international collaborators.
To develop their 3D concrete printing system, the research team connected the 3D printer to CO2 Pumps and a nozzle that releases steam. When activated, this system injects CO2 and steam into the concrete mix during the printing process. CO2 interacts with the concrete components and transforms into a solid state that remains contained within the material (sequestered and stored).
At the same time, steam improves the absorption of CO2 into the 3D printed structure and thus improves its properties. In laboratory tests, researchers found that the printed concrete structure had a 50 percent improved printability, meaning it can be shaped and printed more efficiently. The structure also showed better strength and durability.
Additionally, the structure demonstrated improved strength and durability, having up to 36.8 percent greater compression (the amount of weight it can support) and up to 45.3 percent greater compression compared to standard 3D printed concrete percent more bend (how much it can bend before it breaks). Notably, the method is also more environmentally friendly, absorbing and binding 38 percent more carbon dioxide compared to traditional 3D printing methods.
“We are at a critical time as the world accelerates its efforts to achieve climate goals. We believe our technology could help make the construction industry more sustainable.” said NTU School of MAE PhD student Lim Sean Gip.
Co-author Dr. NTU School of MAE research associate Daniel Tay said: “Our proposed system shows how capturing carbon dioxide and using it in 3D concrete printing could lead to stronger, greener buildings and advance construction technology.”
A joint US patent application was submitted by NTU and its partners for the innovation. In their upcoming research, the team wants to improve the 3D printing method to increase efficiency and potentially explore using exhaust gases instead of pure carbon dioxide.
Magazine reference:
- Sean Gip Lim, Yi Wei Daniel Tay, Suvash Chandra Paul, Junghyun Lee, Issam T. Amr, Bandar A. Fadhel, Aqil Jamal, Ahmad O. Al-Khowaiter, Ming Jen Tan. Carbon capture and sequestration with in-situ CO2 and steam integrated 3D concrete printing. Carbon Capture Science and Technology, 2024; DOI: 10.1016/j.ccst.2024.100306