I was recently invited to the US Army’s Engineer Research and Development Center’s (ERDC) Construction Engineering Research Laboratory (CERL) in Illinois to see a live demonstration of its Automated Construction of Expeditionary Structures (ACES) technology. Last year, the US Army used ACES to 3D print a complete barracks, or B-Hut, in 21.5 hours with the Army’s patented concrete mixture. However, that was just the total amount of print hours, and not a continuous print.
Having only seen still images and video of this unique technology, I knew I couldn’t pass up the opportunity to see a 512 square foot barracks 3D printed live in front of my very eyes within 24 hours. So yesterday afternoon, I hopped in my car for the roughly four-hour drive out west to Champaign.
The goal for this ACES demonstration is to successfully 3D print the exterior concrete walls of a 8 foot building in 24 hours. While the ACES team and its project partner, Chicago-based architectural and engineering firm Skidmore, Owings, and Merrill (SOM), are both onsite, Marines from the 1st Marine Expeditionary Force are running the equipment; obviously, if the project is successful and this technology is able to be deployed overseas to our troops in the future, they will be the ones actually 3D printing the structures.
Benton Johnson, PE, SE, the Associate Director at SOM, told me yesterday that the Marines were briefed on the ACES technology and equipment via conference call and email. From the looks of things, they seemed to have gotten the hang of everything – preparing and mixing the materials, running the computer, cleaning up the printed layers by hand and clearing away material from the bolts, etc. Johnson pointed out that the main coder of the project was onsite, but only to offer assistance if needed.
“I think part of this is a learning curve, because all the Marines that were out there operating the machinery had never seen this or touched it before,” Captain Matt Friedell told me.
“But they took to it, and once they learned it, they started to get in their groove and really pick up the pace. And we knew when we were going to attempt this that it was going to be a challenge.”
Obviously, there were a few glitches, as people rarely get the hang of new technology perfectly the first time out. The barracks is being 3D printed in two halves, and at one point the Marine running the computer accidentally sent the nozzle over to the side that wasn’t being worked on yet; later, when steel dowels were being added for initial reinforcement to the first 18″ or so of 3D printed concrete, work began on the wrong side. But none of this seemed to slow the process down.
However, as I mentioned yesterday, things did not start off swimmingly. Program manager Michael Case, PhD, told me that one of the issues with concrete is evaporation drying. So when the forecast showed rain today, the start time of the demonstration was moved up a few hours, only to halt again pretty quickly. Dr. Case explained that the material used at the Fort Leonard Wood demonstration a few months ago was sharper and more angular than it is here at CERL, and tore up the inside of the pump.
By the time the team finished replacing the pump and working the kinks out of the hose, it was almost the original start time of 5 pm. it looked like things were going to start moving, until the material didn’t extrude properly and some team members removed the nozzle to find that a rock inside was jamming things up. When the concrete finally started to print, the material mixture had to be adjusted after the first layer because it was too sloppy. But once this was fixed, things really took off, and work continued through the night, with very few clogs.
Spoiler alert: when I arrived back at CERL this morning, I learned that the team would not be able to make its original deadline of 24 hours. Dr. Case explained that “a big part of this is to figure out how long you can continuously use the equipment.”
“So we learned a lot about things…If you operate this type of concrete printing equipment long enough, you have to stop and service some of the equipment.”
Dr. Case said that if you don’t clean out the equipment, you can get concrete curing inside of the pump, and that it will eventually shut down, which caused some delays overnight. So by about 9 am this morning, the team had nearly completed the first half of the structure, and was planning on taking a few hours of much-needed rest before starting in on the second half.
While the ACES team won’t make the original goal of a continuous 24 hour print, the work they’ve completed and will continue throughout the rest of the day and night is extremely impressive. Capt. Friedell told me as I was leaving CERL that he was certain this project is the tallest continuous 3D print in the US.
Stay tuned to 3DPrint.com for a more in-depth look at my visit to CERL this week! So far it has been very exciting to be able to have unfettered access to the site and to have been given access to all of the people involved. Issues with extrusion, rain and the weather that this team had actually made me question more the validity of some “3D printing a house in a day” claims. What this team encountered were real-life challenges brought on by equipment and the weather that slowed them down. I think that CERL’s effort, undertaken with a journalist present, was much more transparent, open and honest than the commercial house printing initiatives who somehow always tell us after the fact the great feats that they’ve accomplished. I can now really see the value that 3D printed structures could have for the Marine Corps, Army and for civilian use. Most of all I’m grateful that I got an up close and personal look at what it actually takes to 3D print a structure.
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