Source: Marine Corps Systems Command, U.S. Army Corps of Engineers Construction Engineering Research Laboratory, Champaign, Ill.
Marine Corps Systems Command and 7th Engineer Support Battalion staff joined U.S. Army Corps of Engineers Construction Engineering Research Laboratory (CERL) colleagues earlier this month to test a 3D concrete printing operation with a late model volumetric mixer feeding a 3-in. nozzle. The demonstration was aimed fabricating a bunker and followed barrack and bridge structure printing with a 2-in. nozzle-equipped assembly.
While the 3-in. diameter nozzle printing is experimental, “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,” notes Megan Kreiger, project lead for the Automated Construction of Expeditionary Structures team at CERL. Increasing from a 2-in. to a 3-in. nozzle allows printing of larger structures faster and with less waste, she adds, and drives the team’s pursuit of a 4-in. nozzle for future equipment development.
Along with the larger diameter mix hose and nozzle, this month’s 3D concrete printing operation incorporated a continuous volumetric mixer similar to one adopted for the Marine Corps Airfield Damage Repair Kit, notes Captain Matthew Audette, project officer for the Advanced Manufacturing Operations Cell at Marine Corps Systems Command, adding, “That means we don’t have to field a new piece of gear in addition to the printer to make this work.
The 7th Engineer Support Battalion Marines plan to build a conventional bunker similar to the 3D-printed version and compare both structures in blast or demolitions testing on a range. They envision a printing system modeled after CERL equipment being operational within a few days of deployment to a forward operating base. 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 Automated Construction of Expeditionary Structures team data, 3D printing versus conventional fabrication methods reduces concrete structures’ cost by 40 percent, construction time by 50 percent and material consumption by 44 percent. Additionally, it more than doubles wall strength, improves thermal energy performance by 10 times, and reduces manpower by 50 percent.