I’m converting my basement to a rental unit and due to head height limitations am planning to leave the old concrete slab exposed.  Due to the age, I’m positive there is no sub slab vapor barrier therefore I’m looking for a coating/sealer that can be put on the old concrete slab that will act as a vapor barrier and be left exposed to foot traffic or have a corresponding final coating that installs over it that can be exposed to foot traffic.  I will be cleaning and grinding the old slab (but its in very good condition for its age) so clear would work but also a tintable coating may be even better.