Ceramic Tile & Moisture Testing

[moonrock1]

I have been installing ceramic tile over 30 years & we have never been ask to moisture test concrete,untill now. Why the sudden change about the effects that moisture has on ceramic tile when we use a cement base material to in stall our product? The most series problems we have to deal with is expansion & Contraction joints,an if installed correctly,there is very few problems with that.

Thanks Joe