Researchers based at Cornell University have developed a method for the 3D printing of structures on the seafloor. Traditional methods of underwater construction and repair are slow, expensive, and can disrupt ecosystems. Using robot-based 3D printers and a specially formulated anti-washout concrete mix (using mostly seafloor sediment) represents a breakthrough in subsea construction technology.
The Cornell Chronicle blog mentions that the interdisciplinary group, led by Sriramya Nair, assistant professor of civil and environmental engineering in the David A. Duffield College of Engineering, was already working with a 6,000-pound industrial robot for large-scale 3D printing of concrete structures on Terra Firma.
Sriramya Nair and team members (Image credit: Cornell University
This preassembled team spotted the Department of Defence’s Defense Advanced Research Projects Agency (DARPA) call for proposals, in search of 3D printing concrete construction tech which could be used several yards beneath the sea. “We said, ‘Hey, let’s just do this and see, so that we will at least understand what the challenges are,’” recalls Nair.
The researchers' hunch largely paid off, with an award of a $1.4m grant, contingent on meeting certain benchmarks, and promising early sub-sea results.
Among the major challenges of 3D printing concrete underwater is washout, where the cement washes away more than binds to itself or its intended location. The Cornell team managed to overcome this hurdle with an experimentally optimized balance between material viscosity and pumpabiliity. The video below shows the team testing their underwater 3D printing systems in large water tanks.
Cornell University team demonstrated underwater concrete printing with minimal ocean disturbance. - YouTube Watch On
DARPA also set out a specific challenge to overcome: the agency wanted the concrete mix to incorporate seafloor sediment as a major ingredient. This requirement was set for logistical purposes, but would also help minimize environmental impact – repurposing materials already present in the underwater area.
The researchers also had some work to do on new sensing systems so they could carefully monitor and adapt the underwater 3D printing process in low-visibility conditions.
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