Tech on the Tundra: Corps researchers explore 3D printing with ice

When you’re working with limited resources, sparse and extreme landscapes can present engineering challenges — a cold, hard reality for the U.S. Army Corps of Engineers (USACE). That’s why, in frozen regions such as the Arctic, ice can be an important construction material, says Emily Asenath-Smith, research materials engineer at the Corps’ Cold Regions Research and Engineering Laboratory (CRREL).

“When you get up into cold regions, you might be in an area where ice and snow are the only abundant resources you have, and the logistics of supplying building materials is extremely cost prohibitive,” she says. “The U.S. Army leverages ice as a resource quite frequently. Ice can serve as the base of a bridge or can be packed into blocks of snow and formed into an igloo for shelter.Working with ice presents a major drawback, though: “Team members frequently get frostbite from the extensive exposure involved in building a shelter, for example,” Asenath-Smith says.To explore applications of ice construction that minimize risk, the USACE has been studying 3D printing of ice structures at CRREL, a facility in New Hampshire with 26 temperature-controlled “cold rooms,” where  lab temperatures range from 40 degrees below zero Fahrenheit to 110 degrees.“When we started this project, we were making millimeter-sized objects and using liquid nitrogen to freeze it. Now, we’re working on a mixture with a high enough viscosity to shoot through a nozzle, which will have enough support to hold its shape until it freezes,” says Kiera Towell, another CRREL research materials engineer.

The ice is combined with cellulose nanofibers derived from milled wood pulp, a naturally available resource in places such as Montana and North Dakota, where this technology could be applied.At the CRREL, Asenath-Smith says, “We built a bridge out of ice which was strong enough to support a Humvee. All the cellulose that supported this bridge could have fit in a backpack.”Asenath-Smith, Towell, and the rest of the team are now working on printing mid-sized structures at the CRREL, with hopes of using the technology in the field within the next two years.