Recently, the University of Virginia School of Engineering and Applied Science , engineers have conducted a pioneering research on how CNF – a new plant-derived material – can enhance 3D-printed concrete technology.
Ozbulut and his research team, including the project lead Osman E. Ozbulut, made up of members in the faculty of the Department of Civil and Environmental Engineering, point out that the incorporation of CNF to 3D-printed concrete mixtures may improve the concrete’s performance and sustainability. Thus, the enhancements Perry & Ozbulut noted in printability and mechanical properties indicate that the use of cellulose nanofibrils in construction can help speed up the development of more resistant and environmentally friendly practices. The findings are set annually at the September 2024 issue of the Cement and Concrete Composites journal.
Innovations have seen structures of printing concrete structures and demolishing the construction field as it is a fast method, cheaper, alternatives of wastes can be used, fewer labors and complex structures that cannot be constructed using conventional means. It entails a specific printer that forms structures with the help of a cement-based composite and an application for computer aided design. However, up to the present time, the option of printable materials is not very wide, and problems with sustainability and material’s PtD remain.
The rationale for the new approach is simple: ‘We are responding to a dilemma of managing contradictory goals,’ Ozbulut said. It has to be pourable to achieve the desired fabrication, but it must also set to a rigid material possessing required characteristics such as adequate mechanical strength, cohesion between the layers and low thermal conductivity.
To this end, cellulose nanofibrils which are obtained from wood pulp can be regarded as a more environmentally friendly option. Known as CNF, this material has possibilities of being in the form of additive to improve the rheology and mechanical properties of concrete composites.
Prior to this study, the impact of CNF on conventional 3D-printed composites was largely uncharted. “A lot of trial and error goes into designing these mixtures,” Ozbulut said. “Our research aims to provide a solid scientific foundation to better understand how different additives can improve 3D-printed structures.”
The team, including Ph.D. alumnus Ugur Kilic, tested various concentrations of CNF and found that an addition of at least 0.3% significantly enhanced the flow performance of the mixture. Microscopic analysis of the hardened samples revealed improved material bonding and structural integrity. Further testing demonstrated that CNF-enhanced 3D-printed components also exhibited better resistance to pulling, bending, and compression.
