The City of Nome and its partners are planning to build a demonstration home next summer – using a robot that prints concrete.
They hope the project will prove that the technology can slash the time and cost to build quality housing, even in Alaska’s most remote communities where it’s expensive to build and housing shortages are chronic.
The 3D printing system to build the home will come from 3,600 miles away, in Pennsylvania. Researchers and entrepreneurs working at Penn State University have built a prototype of the system. They’ll use it, or a newer version of it, in Nome to print the unfinished portions of an entire house.
“We are interested in printing everything: the foundation, the walls and the roofs by finding and developing the technology to print domes and vaults,” said Penn State architecture and engineering Professor Jose Duarte. He works in the university’s Additive Construction Lab and its spinoff business, X-Hab 3D.
Sending building materials and skilled workers off the road system is particularly expensive, and the short shipping and construction seasons further complicate the logistics. In some communities, materials must be over-wintered because there isn’t enough time to build after delivery.
Theoretically, 3D concrete printing systems have huge competitive advantages under rural Alaska’s construction constraints and logistics challenges.
Here’s why. Penn State’s system has three main pieces that all fit inside a 20-foot shipping container: A concrete mixer, a pump and a beefy, bright orange robotic arm with a 12-foot reach. The robot arm is mounted on a mobile platform.
“Our current system that we’ve designed at X-Hab 3D is a mobile expeditionary 3D concrete printer,” said Penn State engineering Professor Sven Bilén, who’s also on the team. “It’s on tank tracks. It’s able to roll out of the shipping container and then move around the site on those tank tracks.”
Once in place, the robot arm holds an extruder vertically, like a big pen, putting down a smooth, ropey stream of concrete in precise patterns. As the ropes stack up in layers, a three-dimensional form takes shape.
Without molds holding the soft concrete in place, it’s a bit of an engineering feat to get shapes to come out as intended, instead of a sagging, lopsided mess. Duarte said the system has to account for the particular properties of its concrete mix, how the concrete deforms as more is layered on top, even how the ambient temperature affects the curing time.
“So when you go to a place that is very cold, like, you know, the case of Alaska, or you go to a place that’s very hot, like the case of a desert, you change completely the environmental factors,” he said. “But if you have this platform, you can use the same type of rules, the same type of simulation analysis tools to find out what’s the best configuration for that type of environment. So in a nutshell, that’s the idea that we’re trying to explore.”
The Penn State team says it isn’t ready to share specifics about the project in Nome yet, but their past research was part of a 2021 feasibility study on 3D printed homes in rural Alaska. The study found a ton of benefits over traditional homebuilding.
Traditional builders would need one to three months to do what the 3D printing system could do in as little as one to three days.
A lot of the sand and gravel used in the different concrete mixtures can be locally sourced, which means huge time and cost savings, plus a lower carbon footprint.
The study says the homes should stand up to snow loads, frost heaves, extreme winds and earthquakes, and last longer with less maintenance than a regular home.
The cost savings are also potentially huge. Based on pre-pandemic Fairbanks market data, the researchers estimated that the shell of a concrete home would cost about one-fourth what a traditional one would.
And Duarte said because the different building elements are designed digitally, mass customization becomes possible. That’s good for aesthetics; buildings don’t have to be cookie cutter copies to keep costs down.
But there are practical benefits, too. Duarte said artificial intelligence can generate design options to fit specific build sites, individual families’ needs, the raw materials locally available and a range of expected weather.
“So you can actually customize the building materials for the performance,” Duarte said. “Because, when you have extreme conditions, it’s more difficult to find solutions that are satisfactory, and that’s why you need to use this technology. So we search to work for environments where the conditions were very difficult.”
A lot of eyes are on the Nome project. The Alaska Housing Finance Corp. and Denali Commission paid for the feasibility study.
“There’s really some Alaska-specific challenges to it,” said AHFC CEO Bryan Butcher. “But it’s really exciting to look and to see if it’s something we might be able to solve, because if we can build high energy efficiency homes in rural Alaska at an affordable price, it’s really going to be a game changer.”
The federal Department of Housing and Urban Development recently awarded Nome and its partners a $600,000 grant for the demonstration build.
Nome is contributing land. City Manager Glenn Steckman shared his own housing situation. He rents an older, 900-square-foot house that he said “tilts a little bit” for $2,000 a month plus utilities.
“On top of that, Nome has been working to get people to either tear down old housing or to try to get it repaired,” Steckman said. “But some of the housing is past saving. So we just need to get more housing up here, and quality housing and safe housing. And that’s been a priority for the four years that I’ve been city manager in Nome.”
Steckman hopes the demonstration home will be the first of many. The city is expecting the demand for housing to only increase as construction on a port megaproject gets underway and medical facilities expand.
Bilén with Penn State said right now, the 3D concrete printing industry doesn’t really exist. His team’s origin story only goes back to 2015, when it came together to compete in a NASA challenge to develop 3D printed habitats for Mars. Here on Earth, building codes and regulatory agencies still have catching up to do.
But Bilén thinks the technology is poised for widespread commercialization, with applications far beyond housing. Like cable housings, sewers, even artificial reefs to mitigate coastal erosion.
“And as those applications grow, and more uses in this, I think you’re just gonna see 3D concrete printing explode,” Bilén said.