The University of Arkansas College of Engineering recently received a $3.5-million grant from the U.S. Army Corps of Engineers to study the quickest way to 3D-print horizontal mission structures for the U.S. military.

The task is to identify optimum design patterns from native materials that can be used for horizontal construction—projects longer and wider than they are tall. These include culverts, T-walls and Jersey barriers. The output will include printing instructions for mobile robots that can be rapidly deployed, according to a release from the college.

The research will explore new material structures and geometric configurations to maximize efficiency and outcomes by examining biomimetic naturally occurring designs. One example is a honeycomb pattern that would use less material and strengthen the structure, according to Michelle Barry, an associate professor of civil engineering and the principal investigator. 

“This grant will enable us to invest in research and development, driving the innovation of our swarm 3D printing technology and unlocking new possibilities for the future of construction and other industries,” says Wenchao Zhou, an associate professor of mechanical engineering and co-principal investigator.

Swarm 3D printing, also known as cooperative 3D printing, is a digital manufacturing platform that uses mobile robots with different functions to print and assemble products based on digital designs. 

One area of study concerns 3D printing temporary structures in disaster zones. The goal is to create structures or roads using native material, such as soil, so responders only have to bring in equipment, not materials as well. "If the local soils work, you print with them for the time being, people are sheltered and then once [the structure] is not needed, it dissolves back to the original landscape,” says Barry.

But first, indigenous soils need to be catalogued and classified to determine viability for use in concrete mixes. Soldiers would have instructions for mixing concrete using local soils that “can be pumped through nozzles of the 3D printer with the requisite robot on site,” according to the college. The study includes testing large-scale experimental forms.

The cost of a 3D printer will drive the project’s price tag, says Barry, adding that more than a dozen graduates and post-doctoral students, researchers will contribute to the project. Funds are set aside to purchase a large-format 3D printer and additional equipment for soil and concert analytics, says Barry.

The two-year grant comes as part of a larger $12-million award Applied Research Associates received from the U.S. Army Engineer Research and Development Center. Part of the Corps, the center has invested in exploring 3D printing and concrete in construction of infrastructure projects over the past several years.

In 2018, the Corps used 3D printing to construct 9.5-ft-tall reinforced concrete walls for barracks. At the time, it was “setting their sights on a future project” using 3D printing of concrete roof beams, ENR reported at the time

In 2021, the Corps entered a partnership with Geocycle and its parent company LaFargeHolcim to study how debris from demolition and construction sites, mainly concrete, could be used for energy recovery and mineral recycling, as reported in ENR.