Concrete is not actaully waterproof so needs a real good sealer. Funny we travel to Europe a lot and I hve not seen concrete shower floors . I use 12 x24 porcelain tile in bathrooms for both bathroom floor and showers wall with the same tile only smaller for showers floors I have often usedd that tile in a style that looks like concrete so thta is what I would do . BTW the teak you show sits above a proper waterproofed floor usually .

Concrete is a very porous material. Water will wick a long way in it, and damage your framing. If you want concrete as a finished floor for a bath, you have to plan from the beginning of the build to recess the slab pour for the bath, and especially the shower. It's then built up to the proper slope, waterproofed, and then micro-topped. You are far too late in the process to do any of that, unless you want a height difference, curb, and threshold.

Thanks. Can they grind it down now in that shower floor area (admittedly an extra cost) to get the proper setup? Alternatively if we were willing to accept the change in height to have a lip what would the process be? Are you thinking something like the bellow?

grinding it down after installation may not get a clean finish, corners and all.

How far along are you?

What kind of finish did you plan for?

I wanted this concrete look from the start. I just didn’t realize we would need to plan at the slab pour. Lessons learned I guess!

Your shower areas should have been recessed. They weren't? Then you will have to do a mud bed build up with a slope, and waterproof it, then, you can use a concrete microtopping for the floor and wall. You will be stepping up and into a shower that is higher than the room floor, and has a curb separating it from the room.

It really has to be done at the slab pour - and pour a recess that can be waterproofed (we used a custom pan, and then leveled up with the rest of the concrete at a later time. It leaves a seam, but we were doing an all over floor covering so that wasn't an issue for us.

I can offer teak shower floor experience - it is a pain to keep reasonably clean. As mentioned, those teak floors sit above the shower floor. It will discolor and that didn't bother me much. The mold/mildew/soap scum bothered me very much. The "floor" was heavy and difficult to lift and clean under.