As you can see, to do it right just so the CP can be anchored to the concrete the CP needs to sit ON top of the concrete, not having it poured up against the bottom tubing.
So, if I had a existing metal CP already sitting in place, I would move it to the side or raise it up and put it on temporary supports. Just so I could pour my slab under it, and about two inches to the outside of it, all the way around it. JMO though