The Benefits and Challenges of On-Site 3D-Printed Construction: A Case Study.

In 2018, U.S. Marines, Navy, Air Force, and Army Corps personnel demonstrated the capability of 3Dprinted construction in an expeditionary environment at Camp Pendleton, California. The tri-service exercise culminated in the construction of a 10-meter concrete bridge - the first of its kind to be both printed and placed in a field environment. In this exercise, the 3D printer was transported from Champaign, Illinois to Camp Pendleton, where a team of Marines assembled it close to where the bridge would be placed. The Marines performed initial beam and pier design; the Army Corps completed the structural design, steel reinforcement, and coding. The concrete ingredients were measured and mixed using a volumetric mixer and skid steer. After mixing, the concrete was pumped through a hose to the printer nozzle. Each beam was printed sequentially; the piers were printed concurrently. Reinforcement and forklift pockets were laid manually during pauses between print layers. As printing progressed, the finished members were covered and allowed to cure for two to five days before placement. Despite challenges with weather, materials, hardware, and power, the U.S. military successfully demonstrated the potential of 3D-printed construction in the expeditionary environment by proving it is possible to print and place a bridge on-site using locally sourced materials. The U.S. military also exhibited the potential of 3D printing to reduce the labor, materials, and logistics required for military construction. Furthermore, the exercise revealed additional, future opportunities to automate the 3D printing process and lessen the manpower demand. [ABSTRACT FROM AUTHOR]