Was concrete commonly used for 2nd floor flooring in multi-family apartment units built in 1950s?
When asbestos was used in everything from cooking pan trays to attic insulation on ducts I don't remember hearing of it being mixed into concrete walls or floors.
Even if it was used with the concrete the only way to release it and have it become air borne (where it is a hazard through inhalation) would be if the floor was chiseled or ground on. Mopping or other passive forces can't pulverize the concrete to create asbestos particles. It is (if actually added to) forever entombed in the concrete.