3D printed nanocellulose for green building applications

The hydrogel material made of nano cellulose and algae was tested as an alternative and more environmentally friendly building material for the first time. This study from Chalmers Institute of Technology and the Wallenburg Wood Science Center in Sweden demonstrates how to 3D print rich sustainable materials into various building components, using much less energy than traditional building methods.

The study has been published in the journal Materials and Design.
Nowadays, the construction industry consumes 50% of global fossil resources, generates 40% of global waste, and contributes to 39% of global carbon dioxide emissions. There is increasing research on biomaterials and their applications in order to transition to a greener future based on European green agreements and other initiatives.

Nanocellulose is not a new biomaterial. Its characteristics as a hydrogel are well known in the biomedical field. Due to its biocompatibility and wetness, it can be 3D printed into scaffolds for tissue and cell growth. But it has never been dry and used as a building material before.

"We have explored the structural application of nano cellulose hydrogel for the first time. Specifically, we have provided the missing knowledge about its design related functions so far, and with the help of our samples and prototypes, we have demonstrated the adjustability of these functions through customized digital design and robot 3D printing," said Malgorzata Zboinska, the main author of the study at Chalmers University of Technology.

The team used nanocellulose fibers and water, and added an algal material called alginate. Alginate enables researchers to produce 3D printable materials because it adds extra flexibility to the material during drying.

Cellulose is hailed as the most abundant environmentally friendly alternative to plastics, as it is one of the largest industrial by-products in the world. "The nanocellulose used in this study can be obtained from forestry, agriculture, paper mills, and agricultural straw residues. In this sense, it is a very rich material," said Malgorzata Zboinska.

Nowadays, the construction industry is surrounded by digital technology, which allows for the use of a wider range of new technologies, but there is a gap in how to apply these technologies. According to the European Green Agreement, by 2030, buildings in Europe must improve resource efficiency, which can be achieved by improving the reuse and recycling of materials, such as nanocellulose, which is a byproduct of industrial upgrading and reconstruction. As architecture becomes more circular, cutting-edge digital technology is emphasized as an important lever to achieve these goals.

"3D printing is a very resource-saving technology. It allows us to manufacture products without molds, casting molds, and other things, thus reducing waste. It is also very energy-efficient. The robot 3D printing system we use does not use heat, only air pressure. This saves a lot of energy because we only work at room temperature," said Malgorzata Zboinska.

Energy saving process depends on the shear thinning characteristics of nano cellulose hydrogel. When you apply pressure, it liquefies, allowing it to be 3D printed, but when you eliminate pressure, it maintains its shape. This allows researchers to work without the energy intensive processes commonly found in the construction industry.

Malgorzata Zboinska and her team have designed many different tool paths for the robot 3D printing process to observe the performance of nano cellulose hydrogels when drying in different shapes and patterns. Then, these dry shapes can be used as the basis for designing various independent building components, such as lightweight room partitions, louvers, and wall panel systems. They can also form the foundation for existing building component coatings, such as ceramic tiles for composite walls, acoustic components for damping sound, and composite skeleton walls when combined with other materials.

Traditional building materials are designed to last for hundreds of years. Typically, they have predictable behavior and homogeneous properties. We have concrete, glass, and various durable hard materials that we know will age over time. In contrast, bio based materials contain organic matter, which is designed from the beginning for biodegradation and recycling back into nature. Therefore, we need to acquire new knowledge on how to apply them in architecture, as well as how to accept their shorter lifecycle cycles and heterogeneous behavior patterns, more similar to those found in nature, rather than in artificial and completely controlled environments. "Design researchers and architects are currently actively seeking ways to design products made from these materials, both in terms of functionality and aesthetics," said Malgorzata Zboinska.

This study provides a first step in demonstrating the amplification potential of dry environments and 3D printed nanocellulose membrane structures, as well as a new understanding of the relationship between material deposition pathways and size, texture, and geometric effects in the final structure through 3D printing design. These knowledge are necessary stepping stones that will enable Malgorzata Zboinska and her team to further research and develop the application of nanocellulose in building products that need to meet specific functional and aesthetic user requirements.
The characteristics of new bio based materials are not yet fully understood, which has prompted architectural researchers to establish alternative methods to design these new products, not only in terms of functional quality, but also in terms of user acceptance. The aesthetics of bio based materials are an important component. If we want to propose these bio based materials to society and humanity, we also need to cooperate with design. This becomes a very powerful factor in accepting these materials. If people do not accept them, we will not be able to achieve the goals of circular economy and sustainable building environment.

Source: Laser Net