Steam helps the concrete to cure. Base plates are used to stretch the steel rebar core. These help both speed up the process and create a much stronger end product. Steel is very strong in tension and concrete is very strong in compaction. When you combine the two strengths of each, you get an even stronger, more flexible result.
It used to be used for concrete construction work, but only for walls, foundations, etc. You can see how the concrete descends into the pipe almost dry with normal molds. this gives them the ability to form it somehow, then spinning spreads it out without turbulent water in the mix. It does not have enough water to cure, so steam is added. Brilliant.