In the United States a submarine 3‑dimensional printer was developed for direct concrete printing on the ocean floor

New underwater construction method: 3‑D printing concrete structures directly on the sea floor

Who is working on the project? Researchers from Cornell University
Where and why is the technology needed? On the seafloor – for fast, cheap, and safe construction/repair of ocean facilities
Who funds it? DARPA

1. Why this matters
- Traditional underwater construction methods require large costs, long time, and often disrupt marine ecosystems.
- In the absence of alternatives we have to “make do” – but now a new possibility emerges.

2. Funding and DARPA requirements
- Grant: $1.4 million from DARPA.
- Key condition: use seafloor sediments (materials from the ocean floor) as the main component of the concrete mix. This increases environmental friendliness and reduces logistics – materials can be extracted right on site.

3. How they solve material washout
- The main difficulty of underwater printing: cement is washed away until it hardens.
- The team optimized the viscosity of the mix and its ability to “flow” without losing shape.
- The concrete contains predominantly marine sediments, as required by DARPA.

4. Technical details
Element | Description
Printer | Industrial 3‑D printer (≈ 2700 kg) – previously used on land, now prints in a pool without fully submerging.
Sensors | New imaging sensors allow process control even in murky water where ordinary cameras “lose sight”.

5. Tests and results
- Trials conducted in large water tanks.
- Demonstrated successful printing with minimal environmental impact.
- The technology allows building/repairing on site, without lifting materials to the surface or involving divers.

6. DARPA competition
- Cornell is among six participating teams.
- In March a contest will take place: each team must print an underwater arch according to specified parameters.
- Success will demonstrate the real potential of the technology.

7. Application prospects
- Foundations for offshore wind farms.
- Underwater data centers (UDCs).
- Any other infrastructure requiring construction/maintenance underwater.

Thus, Cornell’s development is already considered a significant step toward new approaches in creating and maintaining marine structures.