The U.S. Army Corps of Engineers’ Automated Construction of Expeditionary Structures (ACES) program is a game changer for construction in remote areas. The project will supply rugged 3D concrete printers that can go anywhere and print (almost) anything. The project started several years ago when concrete printers were very much in their infancy, but even then it was obvious that commercial products would not fit the Army’s needs.
“Our priority was to develop a capability utilizing 3D printing technology for use in an expeditionary environment, specifically suited for military purposes,” Megan Kreiger, program manager for additive construction at the Army’s Engineer Research and Development Center, told me. “That means it has to ship in a container, it has to use local materials, it has to work in a dirty environment, and it needs to be able to take a beating while still remaining reliable.”
ACES has produced multiple printers working with different industry partners. For example, ACES Lite was made in partnership with Caterpillar under a Cooperative Research and Development Agreement. It packs into a standard 20-foot shipping container and can be set-up or taken down in 45 minutes, has built-in jacks for quick leveling and can be calibrated in a matter of seconds, making it more straightforward than other devices. Overall the printer resembles a gantry crane, with a concrete pump, hose and a robotic nozzle which lays down precise layers.
“It’s like a desktop 3D printer where you have a continuous feed of material, but it’s concrete rather than a roll of plastic filament,” says Kreiger.
ACES Lite can be attached to any concrete mixer, and not just the standard Army types. While 3D construction printers typically require specialty mortar, ACES is designed to work with local materials. This has involved considerable work with using concrete incorporating aggregate. The results are impressive, and ACES has demonstrated how it can make barracks, bridges, bunkers, barriers or other structures almost at the press of a button.
According to the ACES website, 3D printing can complete a sample structure in one day rather than five, with a crew of three rather than eight, and with less logistics overhead. Kreiger notes that not only does it reduce labor, in particular it reduces the need for heavy, back-breaking labor. The construction team of the future may need more brains than brawn.
Brains will certainly be needed to take full advantage of the freedom of design that 3D printing gives, which is only limited by the imagination.
“Similar to what 3D printing does for manufacturing, you can create complex shapes very easily at little to no added cost,” says Kreiger.
Rather than being constrained to standard shapes, everything can be customized to demand. You are no longer limited to one set of Lego blocks. If you want built-in insulation, or a certain thickness of concrete for protection, or a particular size or shape of opening, the system can do it. ACES can build structures which would be challenging with normal methods: for example, a demonstration 3D-printed barracks building has walls which are curved at the base for strength and flat higher up.
Build quality is also markedly better than sometimes seen remote areas.
“In an expeditionary environment, buildings are designed to meet U.S. standards, however they often times are of lower quality due to unanticipated field conditions, logistics of construction, and material quality in remote areas,” says Kreiger.
With 3D printing though, everything can be made to the same high standard. This should mean that as well as being available sooner, buildings will be more comfortable for the occupants and more durable.
And while previously a whole range of different items of equipment would be needed building different structures (barriers checkpoints, bridges), an ACES printer can do everything.
The new technology is not magic, and, as Kreiger says, 3D-printed construction is still construction. It does not do everything. A printed building still requires a roof and finishing touches like any other construction work. In areas with good logistics where equipment, labor and materials are all plentiful, there may be little advantage to the ACES approach. But in expeditionary environments, where all these things are likely to be in short supply, ACES could make a real difference.
ACES will bring some specific military benefits: “ACES will provide an automated 3D printer to construct gap crossings, obstacles, and force protection positions using locally available concrete and other materials at a pace that adversaries cannot match,” according to a budget document.
The technology is likely to spread rapidly beyond the military. Anyone carrying out construction work in a difficult environment, from disaster relief to scientific research to tourism to building communications infrastructure in remote places is likely to see the benefits.
At the moment, the technology seems to be racing ahead of application. Kreiger notes that in the civil world new building codes are needed so that 3D printed structures can be certified safe to use. And for the military, it is a matter of converting people to the idea that 3D concrete printing is not an exotic, unknown technique but simply another tool to deploy as needed. A series of demonstrations are planned, including the world’s first 3D-printed vehicle bridge, and the first ACES printers are likely to be deployed in the field in 2022.