The U.S. Army Corps of Engineers (USACE) needs innovative strategies to reach its ambitious goals for beneficially using the material it dredges.
A new project from the U.S. Army Engineer Research and Development Center (ERDC) is helping meet this target by exploring how 3D printers can transform dredged sediment into a building block for ecosystem restoration.
“With the recent advent of printers that can extrude clay and make complex designs, it became clear to us that we could start using sediment as a resource to create a paradigm shift from being a waste material that needs to be disposed of to a clean environmental resource that can be used on-site, on-demand where it’s needed to 3D-print nature-inspired designs for coastal resilience, habitat restoration and habitat creation,” said Dr. Al Kennedy, a research biologist at ERDC’s Environmental Laboratory.
The idea is to use sediment dredged in USACE projects as printer feedstock to 3D-print coastal infrastructure. Not only would doing so help meet a challenge issued by Lt. Gen. Scott Spellmon, 55th Chief of Engineers and USACE Commanding General, for USACE to beneficially use 70 percent of its dredged material by the year 2030, it would also enable better infrastructure design.
That’s because one of the tenets of the USACE Engineering With Nature® initiative is that incorporating nature-inspired designs into coastal infrastructure can provide maximum resilience, as well as economic, environmental and social benefits. However, doing so has been difficult because of traditional manufacturing constraints.
Rapid advancements in additive manufacturing, or 3D printing, have opened new possibilities, making it easier to create the geometrically complex structures needed to mimic nature.
“Additive manufacturing allows you to do things that traditional manufacturing and subtractive manufacturing don’t allow you to do,” said Dr. Mark Ballentine, a research biologist in the Environmental Laboratory. “And so you get these very complex structures that look more nature inspired, such as mangrove roots or other habitats such as bird nests that aren’t functionally available when you have subtractive manufacturing.”
Given that USACE’s beneficial usage had traditionally hovered around 30 percent, reaching the 70-percent target will demand creativity.
This project is an example of that, building on research ERDC had been doing into additive manufacturing to leverage the technology in new ways.
“In the Environmental Laboratory, we've been looking at additive manufacturing for the past five years to understand the health and safety of potential ultra-fine emissions, as well as printing structures that can potentially remove contaminants from water,” Kennedy said. “But the innovation of this particular Engineering with Nature project is that we noticed that a lot of the habitat infrastructure that's deployed in the environment are very simple geometries like cylinders and cubes.
“We felt that additive manufacturing could add innovation and nature-inspired designs to a lot of these structures that could better serve our coastlines, the U.S. Army Corps of Engineers and the nation.”
Dr. Andrew McQueen, a research biologist at the Environmental Laboratory, said there are a wide variety of ways these 3D-printed objects can be deployed in nature, including habitat restoration, coastal protection and dissipating wave energy.
“We are just now realizing what some of those opportunities are,” McQueen said. “And that is the benefit of this project is we’re really trying to unpack and explore across that continuum of opportunities with additive manufacturing and 3D printing to integrate within nature.”
The cross-disciplinary effort benefits from the expertise of multiple ERDC laboratories. The Environmental Laboratory is leading the project in its conception and studying the features and geometries most relevant for 3D printing as habitat. The Coastal and Hydraulics Laboratory will perform hydrodynamic modeling of the resulting structures.
The Geotechnical and Structures Laboratory and the Construction Engineering Research Laboratory are providing additive manufacturing expertise and exploring the possibility of large-format prints using dredged material directly in the field.
“One of the benefits of additive manufacturing is it can be put directly where we need it,” said Dr. Zack McClelland, a research mechanical engineer at ERDC’s Geotechnical and Structures Laboratory. “So when we talk about manufacturing at the point of need, that is getting as close to where we need that product as possible.
“Maybe it is on the shoreline or maybe it is on a barge system with a printer inside a shipping container. With additive, we have the flexibility depending on what that need is.”
As this research continues to explore the use of additive manufacturing to print nature-inspired infrastructure, using natural feedstock building materials, ERDC hosted a workshop with government, industry and academia in February to foster further collaboration and spark innovative ideas. The workshop included a diverse group of subject matter experts in the fields of material science, toxicology, ecology, mechanical engineering, chemical engineering, landscape architecture, social science and dredging technology.
Among those attendees was Dr. Chris Williams, director of the Design, Research and Education for Additive Manufacturing Systems Laboratory at Virginia Tech University.
“What excites me the most about this new project is it's really taking advantage of everything that we think about when it comes to Engineering With Nature,” Williams said. “It’s the opportunity to use local materials, use our principles of engineering to improve the performance of ecosystems and ensure safety of the coastline, and to do that in a way that contributes back to the ecosystem. That's really exciting.”