The use of under floor vapour barrier is the best method and most economical solution for controlling water vapour migration through concrete floor slabs. The issue of admixtures and topically applied materials does not address the issue that concrete cracks or the potential for elevated PH levels.
ASTM E 1993 and ASTM E 1745 are the two industry standards for vapour barriers and retarders under concrete floor slabs in contact with soil.
Good on quality. Good for environment: Please understand that typical 200 microns polyethylene film does not meet the requirements of these standards because it degrades in this environment due to the high recycled content of the material.