Rust stains and marks on concrete ceiling

Dear forum,

We had planned to leave the unfinished, raw concrete ceiling visible in our new building. However, for cost reasons, we did not order fair-faced concrete. We still really like the concrete, but there are marks from rubber pads on which the ceiling rested, as well as external rust stains caused by contact with the reinforcement. Now the question is whether these can be removed at all and, if so, what the least labor-intensive method is.

First, I want to try to remove the stains chemically. There seem to be good agents available. However, working overhead with ascorbic acid is very difficult. I am not sure if this will be successful.

Our site manager suggests sanding the ceiling completely. However, I am not sure if this is promising or if it will dull the concrete or leave sanding marks visible everywhere later on. Can I sand the spots only partially?

The last option would actually be to fill the ceiling with putty and then paint it. However, I would only want to do this as a last resort. Does anyone have experience with this?

Yes yes, you get what you pay for…
That looks superficial. I would also grind it.
With grinding you can get concrete to a mirror shine if necessary… so the opposite of dull.
How do you want to do the wall connections and joints?

I can't really help you because we haven't built yet, but we also want a exposed concrete ceiling or are considering it. If you have found a processing method for yourself, please feel free to share the result here. I am especially interested in what a polished concrete ceiling looks like. The appearance can ultimately be achieved through the grain size. We will grout the joints with mortar and apply acrylic on the edges; the walls will be white.

How it looks polished depends on the concrete and the grinding.