As tornadoes, hurricanes and other extreme weather events threaten communities, researchers are exploring whether 3D-printed concrete could provide stronger and more affordable storm shelters for people who need them most.
Reese Greenlee, an assistant professor of architecture at Kansas State University, is studying how 3D printing could be used to build storm shelters for manufactured home communities.
Many of these communities have limited access to safe shelter during severe weather.
Greenlee is working with Shelby Doyle, an associate professor of architecture at Iowa State University, and researchers from the university’s Computation & Construction Lab.
Their goal is not only to create emergency shelters but also to design spaces that communities could use for other purposes when severe weather is not occurring.
Concrete 3D printing works in a similar way to a desktop 3D printer. Instead of plastic, however, a machine pumps out specially prepared concrete in layers to gradually create a structure.
Getting the concrete mixture right is challenging. It needs to be liquid enough to travel through the printer and be smoothly pushed from the nozzle. At the same time, it must become firm quickly enough to hold its shape and support additional layers placed on top.
Another challenge is making the printed concrete itself strong enough to serve as the main structural system. Currently, 3D-printed concrete is often used mainly as an outer shell, while a separate structure provides much of the strength.
Greenlee wants to find the right combination of concrete mixture, printing technique and structural shape so the printed material can play a much bigger role in protecting people.
Instead of printing an entire shelter at its final location, the researchers are testing a modular approach. Large sections could be printed in a controlled factory environment, transported to a community and assembled on-site. This would avoid the need to move enormous 3D printers from one construction site to another.
The team is currently testing full-size modules measuring about 4 feet by 4 feet, or 1.2 meters by 1.2 meters. Researchers are experimenting with different printing directions, internal structures and shapes to see which designs best withstand powerful winds and flying debris.
Flying objects are particularly dangerous during tornadoes and hurricanes. Storm shelters built to U.S. safety standards must be able to withstand impacts such as a wooden two-by-four traveling at around 100 mph, or 161 km/h.
The researchers plan to put their printed concrete module through tornado-level testing at an Intertek facility in Minnesota. They will pay particular attention to potentially weak areas, such as doors, windows and the places where separate sections connect.
The research could have significant implications for manufactured home communities. More than 22 million Americans live in manufactured housing, according to the U.S. Department of Housing and Urban Development, and many lack convenient access to storm shelters.
Ultimately, Greenlee hopes to combine architecture and structural engineering to address this safety gap.
If the technology proves successful, modular 3D-printed concrete could provide communities with shelters that are not only strong enough to save lives during extreme weather, but also affordable and useful throughout the year.
