[TowerTalk] concrete set time

[jim Jarvis]

Julio Peralta wrote:

> I've always wondered how the average guy can tell the difference  
> between
> 2500 and 5000 PSI concrete when it's delivered. It's my  
> understanding that a
> test cylinder has to be poured and sent to a lab to determine the PSI
> strength. Couldn't a concrete company tell you its 5000 PSI and  
> deliver
> something much less than that?
>
> Julio, W4HY
>

The only time I did this, we had a structural engineer on the team.    
Before the
concrete was poured, he did a "slump" test.   Poured a cone of the  
stuff, and
measured how much it deflected downward.   Evidently, that's an  
indicator of
the eventual strength of the material.

n2ea

ps:  I agree with Steve.   By letting the concrete company know  
you're testing,
they'll be careful to get the right stuff.