By Taylor Provine
K-State News and Communications Services
As extreme weather intensifies, Reese Greenlee is testing the limits of 3D-printed concrete to create stronger, more accessible storm shelters for vulnerable communities.
Greenlee, an assistant professor of architecture in Kansas State University’s College of Architecture, Planning & Design and Big 12 Faculty Fellow, is researching the intersection of architecture, structural performance, digital fabrication and housing resilience. Specifically, he is investigating whether off-site construction using 3D-printed concrete can provide affordable, adaptable and code-compliant storm shelters for manufactured home communities that lack adequate access to shelter.
He is working on the project with Shelby Doyle, associate professor of architecture at Iowa State University, and researchers in the university’s Computation & Construction Lab, which Doyle co-founded. Their research extends beyond emergency protection to consider dual-purpose spaces that can serve as both community infrastructure and life-saving shelter.
3D-printed concrete: an area for innovation
While 3D-printed concrete has existed for years, it remains an active area for innovation, Greenlee said.
“The issue is that 3D-printed concrete often functions as an outer shell, with another structural system embedded within it,” he said. “My goal is to understand what it takes for 3D-printed concrete to become more of a viable structural system through the particular concrete mixture, printing process and geometry.”
The process builds layer by layer, the same way as 3D printing plastic at a desktop scale, but the concrete must have a particular level of flow, much more liquid than traditional concrete, Greenlee said.
“All of the parameters that are critical for conventional concrete remain important for 3D-printed concrete, but the printing process introduces different requirements,” Greenlee said. “The material needs to flow well enough to be pumped and extruded, but it also needs to become stable enough to maintain its shape and support the layers above it.”
Designing to push the limits
Greenlee’s project is in the testing phase, and they are working at the scale of a single full-size, 4-by-4-foot module building block, because 3D concrete printing traditionally has limitations: if you want to print a large building, you need bigger gantry printers.
“What our project approach has been is to forego that and build pieces off-site in a controlled environment, ship them to a site and assemble them there,” Greenlee said.
“The printing process gives us the opportunity to think strategically about direction. We are testing whether print orientation, infill and geometry can be organized to improve performance under extreme wind pressure and debris impact.”
Windborne debris is a critical concern in tornado and hurricane conditions. Storm shelters designed according to ICC 500 and FEMA P-361 criteria must account for impacts such as a two-by-four traveling at 100 mph.
“In a severe tornado, debris can be pulled from trees, buildings and other structures and carried at extremely high speeds,” Greenlee said. “That is why impact resistance is such an important part of storm-shelter design.”
The next phase of the project will take place at an Intertek testing facility in Minnesota, where the full-scale module will undergo testing at tornado wind speeds.
“Storm-shelter assemblies have to undergo debris-impact testing, and you focus on the places where components come together or where there’s a window or a door,” Greenlee said. “Those conditions can become potential points of weakness.”
Connecting architecture and engineering
At the broader level of architecture as a discipline, Greenlee said the research is important because manufactured housing and the communities associated with it have received relatively little architectural attention.
More than 22 million Americans, or about 1 in 15 people in the country, live in manufactured homes, according to the U.S. Department of Housing and Urban Development.
“It is a substantial portion of the population that has essentially been overlooked,” Greenlee said. “Just as importantly, many manufactured home communities do not have adequate shelter or access to shelter, so they are extremely vulnerable.”
Through his research, Greenlee is connecting architecture with his background in structural engineering to create opportunities in the extreme environment space.
“My role is to connect the social problem to the technical one,” he said. “We’ve identified a major public-safety issue, as well as an economic challenge and a social stigma surrounding manufactured housing. I’m interested in how conventional materials and systems can be pushed to their limits to create shelters that are safer, more affordable and more useful to communities.”
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