Concrete lathes are far from a new idea. During WW1, the US needed more lathes than we had. It could take years for a cast iron casting to age enough sitting outside before you could do the final machining to actually build a lathe.

So concrete was tried as a substitute for cast iron. It has some good properties, it cures quickly, is rigid enough, and dampens vibrations pretty well. The downsides are you require a physically larger machine that takes up more floor space, and they are difficult to move making resale difficult, and they don’t last as long in that usage, so they aren’t cheaper in the long run.

Concrete lathes had their day and quickly died out to be forgotten.