“Concrete cracks and nothing can be done about it” is a common refrain when the material cracks unexpectedly. However, it is too often an excuse when poor design or improper placement has resulted in excessive random cracking. The real problem is too much mix design water, a lack of welded wire reinforcement, insufficient aggregate, or inadequate curing methods…”

Vapor barrier and curing considerations
A vapor barrier should be placed under all slabs-on-ground that will receive floor covering. Properly consolidated concrete is waterproof, but not vapor-proof. If a vapor barrier is not used, any moisture under the slab migrates upward by capillary action through the concrete to eventually degrade the floorcovering adhesive. Most floorcovering manufacturers consider the lack of vapor barrier a defective concrete installation—many void their warranties on that basis.

Learn more about concrete expectations prior to applying your floor covering:

“Mix Design Fundamentals: Considerations for concrete slabs-on-ground”

The Construction Specifier
By: Paul Potts
August 2014

http://www.constructionspecifier.com/mix-design-fundamentals-considerations-for-concrete-for-slabs-on-ground/