For years, 3D Concrete Printing (3DCP) has been an experimental novelty. Alquist 3D, based in Greeley, CO, is pushing the technology past the demonstration phase with their A1X, a robotic arm printer that lays down inch-thick layers at a whopping 200mm/s. This new approach to construction cuts down on time and wasted material, while also requiring fewer people. Alquist 3D is partnering with construction firm FMGI to build more than a dozen expansions on Walmart locations across the country using the new tech.
Alquist’s most ambitious build isn’t 30 new Walmarts or the first 3D printed house in Virginia. It’s the ecosystem the company is setting up to take 3D printing from the lab to the construction site. By teaming up with equipment distributors Hugg & Hall and general contractors like FMGI, they are solving the scalability problem that previously held back the technology and labor shortages that plague construction in general. Alquist recently sold 14 A1 Series systems, in what is believed to be the largest U.S. deployment of 3DCP.
Concrete printers are surprisingly similar to FDM 3D printers, though they don’t need a heated nozzle and cooling fans. They extrude a thick paste of special concrete packed with fibers to control cracks that could form during curing, much like FDM machines might use glass fiber in nylon to control warping. Alquist’s machines run materials by Sika, which utilize recycled fibers mixed with Portland cement.
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We spoke to Andrew Lycas, Alquist’s CTO, about the machines and technology his company is developing. He told us that 3DCP is superior to traditional CMU block construction, AKA cinder block construction, because it’s much faster and requires a smaller team of skilled workers. However, the material costs more, which eats away at the savings.
Alquist 3D recently launched its A1 Series, featuring two units: the A1 and A1X. Both machines are built on a KUKA robotic arm fitted with a 1.25-inch nozzle. The standard A1 sits on a pedestal and is made for producing “smaller” items like planters and park benches. It's also perfect for educational settings to train modern construction crews on large-scale 3D printing. Alquist co-developed a curriculum with nearby Aims Community College to introduce students to 3DCP technology.
The A1X has the same robotic system, but rides on a modular rail, allowing the printer to construct buildings with basically an unlimited X and Y dimension. On the job site, the A1X has successfully constructed walls up to 20 feet high.
Printing in concrete does have its limitations. Unlike desktop 3D printers, there’s no compatible support material, meaning the A1X can print walls but not the roof. However, its super chonky line width enables a “vase mode” style geometry that can smoothly print walls in one pass. “Infill” is applied manually, in the form of heavy wire supports inserted while the concrete is soft. The wall spaces can be backfilled with insulation after electricians and plumbers insert conduit or pipe. Commercial buildings can skip this step and simply bolt utilities to the interior walls.
Early concrete printers used massive gantry systems that looked strikingly like desktop machines. These printers were difficult to transport and set up, and put severe limits on the size of the build. The A1X is a more nimble machine that can be hauled by a pickup truck in a standard trailer and set up in about an hour. Large jobs can make use of several printers working in concert to cut down on job time.
Alquist 3D is partnering with construction firm FMGI to build more than a dozen expansions on Walmart locations across the country, with each one being a little bit different. The first job was in August in Tennessee, with temperatures over 110F during the day. After a frustrating start, the team discovered that going nocturnal helped not only the workers but also the materials, which have an optimal temperature range of 5 to 35 °C, or 40 to 95F. The 8,0000 square-foot expansion only took 140 hours to print once the bugs were worked out.
3D printed concrete really shines in the winter, when it's too cold for traditional construction methods. In January, Alquist 3D built a 4,400 square-foot addition to a Walmart in Lamar, MO, that only took 17 days and 71.3 print hours to build. Temperatures dropped to 24°F with sustained high humidity, but didn’t phase the process one bit.
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