New Technology: Walls That Can Grow Plants.

The relationship between architecture and nature is very complex. If, on the one hand, we enjoy framing nature as art in our homes; on the other hand, we try in every possible way to avoid the presence of "real" blocking properties in our walls and structures, which can be damaged by roots and leaves. At the same time, we use green roofs, vertical gardens and flower boxes to bring the city closer to nature and improve people's welfare; but we also build buildings with materials that are completely separate from fauna and flora. Although advances in biomaterials and new technologies are gradually changing this, we must still ask ourselves whether the structures and buildings we live in need to be separated from the nature that surrounds them. This is the question that led researchers at the University of Virginia (UVA) to develop geometrically complex 3D-printed soil structures in which plants can grow freely.

 

The team has developed a method for 3D printing using bio-based materials and incorporated circularity into the process. They were able to use the material that they were developing, and they are looking to

Instead of traditional concrete or plastic materials, the raw materials used are soil itself and local plants which are mixed with water and fed into the printer to form walls and structures. By combining speed, cost efficiency and low energy demand with locally sourced bio-based materials, additive manufacturing processes can evolve and create 3D printed structures that are completely biodegradable, returning to earth at the end of their life.

The team consisted of Ji Ma, Assistant Professor of Materials Science and Engineering in the School of Engineering and Applied Science at UVA; David Carr, Research Professor in the Department of Environmental Science at UVA; and Ehsan Baharlou, Assistant Professor in the UVA School of Architecture, and Spencer Barnes, a student at the University. Barnes conducted experiments on the mixtures most conducive to imprinting, through two approaches: printing the soil and seed in sequence or mixing the seed with the soil before printing. Both approaches work well.

As Ji Ma points out in this University-published article, "3D-printed soil tends to lose water more quickly and maintains a stronger grip on the water it holds," says Ma. “Because 3D printing makes the environment around the plants drier, we had to include plants that prefer a drier climate. The reason we think so is because the soil becomes solid. When the soil is squeezed through the nozzle, air bubbles are pushed out. When soil loses air bubbles, it holds water more tightly.

David Carr, in turn, was responsible for finding the ideal soil composition for molding and the most conducive plant species. These findings will ensure that plants can thrive within the structure and that the soil can accumulate organic matter and collect the necessary nutrients. He proposed plants that grow naturally in areas that appear to be at the outer limits of life - native plants that grow practically on bare rocks. The species chosen is Sedum (Stonecrop), which is commonly used on green roofs. The physiology of this species is similar to that of cacti and can survive with little water, and can even dry out to some extent to recover.

David Carr, in turn, was responsible for finding the ideal soil composition for molding and the most conducive plant species. These findings will ensure that plants can thrive within the structure and that the soil can accumulate organic matter and collect the necessary nutrients. He proposed plants that grow naturally in areas that appear to be at the outer limits of life - native plants that grow practically on bare rocks. The species chosen is Sedum (Stonecrop), which is commonly used on green roofs. The physiology of this species is similar to that of cacti and can survive with little water, and can even dry out to some extent to recover.

The team published their first results earlier this year in a paper entitled 3D Printing of Ecologically Active Soil Structures. Research around the technology continues and next steps include the formulation of soil "ink" for larger structures with at least one floor, to anticipate problems such as soil breakdown at higher stresses. In addition, the researchers also experimented with various layers inside the wall panels to insulate the inner walls and keep the outer walls moist. While this is just the beginning, it could be a step towards keeping nature closer to human production.