Sure, .006" thick polyethylene under the floor. Otherwise, you can
smear on what you like, and moisture will still come through. (Okay, a
couple inches of tar would work.)
Keeping water from coming through masonry is a challenge- essentially
impossible unless there's an impermeable membrane in there. Drainage is
Keeping radon out essentially means venting it elsewhere, like from
house and ground into under-house ducts through blower and out-there.
IOW, install small vent ducts under slab that are kept at negative
gauge pressure, and dump inflow to the great-outdoors. Check with local
experts, first, to see if you have a problem; second, how best to deal
If you can insulate above and part/most way down the walls, and
ventilate below that to remove moisture, that should serve you well.
Vapor-barrier under floor would help too.