Underwater 3D printing could transform maritime construction

Since it was invented in the 1980s, 3D printing has moved from the laboratory to the factory, the home and even outer space.

Now, an interdisciplinary group of Cornell researchers is developing a way to bring the technology to the ocean. By 3D-printing concrete underwater, the new approach could transform on-site maritime construction and the repair of critical infrastructure that connects continents.

"We want to be constructing without being disruptive," said Sriramya Nair, assistant professor of civil and environmental engineering in the David A. Duffield College of Engineering, who leads the effort. "If you have a remotely operated underwater vehicle that shows up on site with minimal disturbance to the ocean, then there is a way to build smarter and not continue the same practices that we do on the land."

The project got its start in fall 2024, when the Department of Defense's Defense Advanced Research Projects Agency (DARPA) issued a call for proposals to design 3D-printable concrete that could be deposited at a depth of several meters underwater - and to do so in a radically truncated timeframe of one year.

"When the call for proposals came out, we said, 'Hey, let's just do this and see, so that we will at least understand what the challenges are," said Nair, whose group had already been working with a roughly 6,000-pound industrial robotto 3D-print large-scale concrete structures. "And it turned out, with our mixture we could actually 3D-print underwaterby making adjustments to account for continuous water exposure."

In May 2025, the team was awarded a one-year, $1.4 million grant that is contingent on meeting certain benchmarks, with five other teams competing to do the same.

Underwater printing faces numerous challenges. Chief among them is preventing washout, in which cement particles fail to bind together during deposition, weakening the material. The typical solution is introducing admixture chemicals, but these create complications of their own.