vented deck in parking garage

huangyhg

vented deck in parking garage
i have been asked to respond to a report written by a contractor concerning deteriorated metal deck in a steel framed parking garage. the garage is ~30 years old, and the floor is 5 1/2" concrete on 2" galvanized composite steel deck. much of the deck has become severely corroded, in some places it is gone completely! the deck was reportedly sealed with a urethane coating. it has also been reported that urea was used as a deicer.
the contractor's report suggests the urethane coating has trapped moisture, which caused the corrosion, and that a vented deck should have been used. i am familiar with using vented form deck for light-weight insulating concrete, but it does not seem to me that use of (un-vented) composite deck here was inappropriate. i am more inclined to think that inadequate sealing/maintenance has let deicing agents penetrate through the concrete.
is vented deck required for this condition? is use of urea appropriate for deicing on parking decks?
any feedback is greatly appreciated.