[Chellybean]

Originally Posted by GaryW

I am quite aware of this issue,,, The Pop Outs,, alot of debate on that issue.

The are different type of mixes for concrete. Concrete is guaranteed to reach a certain strength threshold if you will. It will reach that strength in 28 days. Alot of mixes for T&D are designed not to "Cure Fast" but to achieve desired strength in a shorter period of time.

Slabs on ground (e.g. pavements, sidewalks, parking lots, driveways, floors, canal linings) and structural concrete (e.g. bridge decks, piers, columns, beams, slabs, small footings, cast-in-place walls, retaining walls) require a minimum curing period of seven days for ambient temperatures above 40 degrees Fahrenheit1.

American Concrete Institute (ACI) Committee 301 recommends a minimum curing period corresponding to concrete attaining 70 percent of the specified compressive strength2. The often specified seven-day curing commonly corresponds to approximately 70 percent of the specified compressive strengths. The 70 percent strength level can be reached sooner when concrete cures at higher temperatures or when certain cement/admixture combinations are used. Similarly, longer time may be needed for different material combinations and/or lower curing temperatures. For this reason, ACI Committee 308 recommends the following minimum curing periods3:


Curing in Construction

http://www.nrmca.org/aboutconcrete/cips/40p.pdf


Little reading for those interested in this type of boring stuff.

tHANK YOU YOU ARE CORRECT BUT I DID NOT WANT TO BORE ANYONE WITH THOSE ACI Committee 308 STANDARDS.