Electrodeposition of dissolved minerals in seawater has been used to make coral reef repairs for quite some time. WOLF H. HILBERTZ patented the process and trademarked the name Biorock. I do not have access to IEEE, so I have only been able to read a small portion of this paper: https://ieeexplore.ieee.org/xpl/mostRecentIssue.jsp?punumber=9015
The author of the article maintained that this process can build a seawall at a third of the cost of concrete, and it was suitable for building underwater constructions. I have only found references to using this process for repairing coral reefs, but none for construction purposes.
If the lower cost and material strength claims are valid, it would seem that this process would make it dramatically cheaper to build buildings at depth that could be used to make oceanic research facilities.
Is this a feasible approach to build ocean floor facilities for research or commercial purposes? Does the material formed have low enough porosity to be used as a building exterior wall?