As an effort to address the growing need for repairing deteriorating buildings, bridges and roads, and building sustainable infrastructure that’s not based on carbon-intensive concrete, researchers have recently introduced a new method of 3D-printing load-bearing structures using local soil.
According to Sarbajit Banerjee, Ph.D., the project’s principal investigator, additive manufacturing has already reduced the amount of waste generated by the construction industry, yet the materials used in the process are often not sustainable.
As an example, in addition to being responsible for approximately 7% of global carbon dioxide emissions, concrete is non-recyclable and has to be transported to the construction site, thereby increasing cost and environmental impact.
“Historically, humans used to build with locally sourced materials, such as adobe, but the move to concrete has raised many environmental issues,” said project co-author Aayushi Bajpayee. “Our thought was to turn the clock back and find a way to adapt materials from our own backyards as a potential replacement for concrete.”
In the study, Banerjee and his team collected soil samples from a colleague’s backyard and tailored the material with a new environmentally friendly additive to enable binding and facilitate extrusion through the 3D printer.
Given the geographic variation in soil composition, the team wanted to have a chemistry “toolkit” allowing for the transformation of any type of soil into a material suitable for 3D-printing mass structures.
Next, in order to improve the mixture’s load-bearing capacity, the team sealed the microscopic layers on its surface to prevent it from absorbing water and expanding, which could otherwise compromise the printed structure.
In the near future, Banerjee and colleagues plan to analyse the data on sustainability they’ve collected during the project to make sure that the material is, in fact, sustainable, as well as to further improve its load-bearing capacity and get as close to replacing concrete as possible.
If successful, the team also has plans for exploring the technology’s suitability for 3D-printing structures on other planets using local materials, which could eventually come in handy as humans progress to manned missions both within, and outside of, the solar system.