While 3D printing technology does allow for the quicker and cheaper construction of buildings, such structures are typically made of concrete, which isn't very eco-friendly. Soon, though, it may be possible to print buildings out of local soil.
The problem with concrete lies in the production of the cement that's used to bind it together. According to some studies, the process is the source of about 8 percent of the world's human-made carbon dioxide emissions.
Looking for a greener alternative, scientists at Texas A&M University turned their attention to the moldable clay soil that is found beneath the topsoil in locations throughout the world.
Staring with clay from a colleague's back yard, they added a non-toxic substance known as carboxymethyl (trimethyl) azanium chloride (CTAC). It's a byproduct of the sugar beet processing industry, and it "zippered" up the microscopic surface layers of the clay. This kept the clay from absorbing water and expanding, which would be pretty problematic if the material were used in a building.
Sodium silicate particles and cellulose fibers were also added, which helped the clay stick together so it could more easily be extruded through the nozzle of a 3D printer.
So far, the researchers have created small-scale test structures, made of stacked printed layers of the treated clay. Before attempting anything bigger, they intend to boost its load-bearing capabilities.
Ultimately, the team hopes to develop a chemical "toolkit" that people could use to convert any type of soil into a 3D printing medium. Not only would this eliminate the need for cement, but it would also minimize the energy expenditures and greenhouse gas emissions involved in transporting heavy building materials over long distances to construction sites.
In fact, the technology could even find use on other planets, allowing astronauts to print structures out of lunar or Martian soil.
The research, which is being led by Prof. Sarbajit Banerjee, is being presented this week in an online meeting of the American Chemical Society.
Source: American Chemical Society
