Rachel Adams- I think one of the reasons we are rather going in circles is that there are roughly two types of construction in high-rise buildings. In very general terms they are:
1. Steel structure, where sectional steel vertical columns are joined with horizontal members. Floors are reinforced concrete.
2. Reinforced concrete, where both vertical and horizontal members are made of concrete with bundles of reinforcing bars embedded. I think there is a limit as to how high this construction can go, though I don't know what that limit might actually be. The building I live in was built this way. It's nine floors because in China, if you have more than nine floors, you have to build in an elevator.
I think the primary area of misunderstanding is with the word plaster. Look in your dictionary and notice there are several meanings- both nouns and verbs- so that may be part of the 'loss in translation'.
If we assume non-finished interior spaces offered for sale:
A. In #1 the bare steel would have to be protected from corrosion by some coating, and perhaps this coating is locally called "plaster". It may look rather like plaster, but is not actually plaster, and some other term should be used if an accurate description is needed in English. I don't know what that might be.
I guess this is your situation.
B. In #2 the as-poured concrete piers, walls, and ceilings may actually be coated with plaster to even out irregularities and make the space more attractive to prospective buyers.
I am confident that "a pasty composition (as of lime, water, and sand) that hardens on drying and is used for coating walls, ceilings, and partitions" is not being applied to steel structural members as in A. above.