Besides the normal prep to place concrete, graded compacted granular base, vapor barrier, use a 10 mil plastic, a lot of guys use the cheap 6 mil store bought visqueen and this stuff falls apart in a few years, tape all over laps and cut outs in the plastic.
Mix design is important. With the vapor barrier you need to use a water reducer in the concrete mix. This allows a lower slump ratio ( less water) to keep the concrete plastic to be able to move it around. This is very important because the vapor barrier doesn't allow the concrete to shed water from below and will trap moisture in the concrete and will take forever to hydrate.
Personally I like a power trowel finish with float blades. The installer can still get a good finish but not glaze the floor. If will be smooth but not so closed up. As far as a topical coating before applying your mastic, you need to follow the manufactures recommendations. I'm not a tile or vct guy and only install/sell overlays and epoxy coatings but the process is the same. gene ec-Indy
Elite Crete of Indiana
www.elitecreteindiana.com
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