US Marines from Marine Corps Systems Command (MCSC) and 7th Engineer Support Battalion (ESB) along with engineers from the U.S. Army Corps of Engineers Construction Engineering Research Laboratory (CERL) conducted the first known 3D concrete printing operation with a three-inch print nozzle at the CERL headquarters in early August in Champaign, Illinois.
The CERL, MCSC and 7th ESB team tested a new continuous mixer and three-inch pump for this print operation after successfully printing multiple structures, including a barracks and a bridge using, a two-inch pump and hose, the US Marine Corps said.
“This is really the first time we’ve ever printed something large with this system,” said Megan Kreiger, project lead for the Automated Construction of Expeditionary Structures—or ACES—team at CERL. “It is experimental right now and we are trying to push the technology forward. This is the first time in the world anyone has really tried using these larger bead systems with these larger pumps.”
Increasing from a two-inch to a three-inch nozzle allows Marines to print larger structures faster and with less waste, according to Kreiger. The teams have envisioned printing with up to a four-inch nozzle in the future.
While this was the first known printing of concrete with a three-inch hose and nozzle, the exercise was also significant because it incorporated a continuous mixer similar to the one currently fielded to Marines.
“The new mixer we are testing is a commercial model of a mixer that is already within the Marine Corps repertoire in the Airfield Damage Repair Kit,” said Capt. Matthew Audette, project officer for the Advanced Manufacturing Operations Cell at MCSC. “That means we don’t have to field a new piece of gear in addition to the printer to make this work.”
This time the team printed a bunker that was designed by the Drafting and Survey combat engineers from 7th ESB based on practical field experience.
“The Marines from 7th ESB are the ones who designed what we are printing today,” said Audette. “They came up with the plans themselves, [Computer Aided Designed] the model, sliced it and then fed it through the printer.”
The 7th ESB Marines plan to build a conventional bunker similar to this 3D-printed version and compare them in blast or demolitions testing on a range.
The combat engineers envisioned a system like this being deployed to a forward operating base, and being operational within a few days of arrival. The system would quickly print small structures that can be transported to entry control points and operating posts in an efficient and timely manner using fewer Marines and less material.
According to ACES team data, 3D printing concrete structures reduces cost by 40 percent, construction time by 50 percent and the use of concrete materials by 44 percent. Additionally, it more than doubles the strength of walls, improves thermal energy performance by 10 times, reduces manpower by 50 percent and reduces the overall need for hard labor.
“With vertical construction, we are still in the realm of what we were doing 100 years ago,” said Audette. “Working with the Army Corps of Engineers to develop this technology we are reducing the man-hours involved, the labor involved and the materials involved.”