[TowerTalk] Concrete Drying Time

[alsopb]

Guys,

I've found limited data on the amount of time
concrete takes to reach nearly full compressive
strength.

The only thing I've found is a table in a PE study
guide.  It gives the % of compressive strength
reached versus time.  

concrete type     3days     28 days
1                 100%      100%
2                  80%       85%
3                 190%      130%
4                  50%       65%
5                  65%       65%

The text defines:
type 1 - normal portland cement
type 2 - modified portland cement. Moderate
sulfate resistance.  Heat rate and heat gegeration
lower than for normal portland cement
type 3 - high-early-strenght portland cement. 
type 4 - low heat portland cement
type 5 - sulfate-resistant portland cement.

Now for the question.  I ordered 4000 PSI concrete
which was further described to be 5 1/2 bag mix.
Which type of the above is this?

The table seems to indicate that 3 days curing
time (if the mix I got is not type 4 or 5) is
sufficient to develop 3000 PSI compressive
strength needed here.

This seems contrary to the rule of thumb I hear
that one should allow 28 days for the concrete
tower base/anchor to develop sufficient
compressive strength.

Any other info out there?  Suggestions?  Advice?
Maybe there are other considerations which warant
longer drying times.  I'm just itching to get the
tower up.

73 de Brian/K3KO

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