Jerry:
Three-thousand pound concrete is the compressive strength of the mix,
in this case 3000 pounds per square inch of surface. Check out
http://www.umeciv.maine.edu/cie111/concrete/strength.htm for a description
of the testing method used for large concrete batches.
The slump is a measure of the amount of liquid (in your case, mainly
water) in the concrete mix. Check out http://www.hrc-engr.com/LabArt4.html
and
http://www.tam.uiuc.edu/courses/TAM224/Lab_manual/01_production_of_concrete.
pdf for somewhat concise explanations of slump and how it's measured. The
higher the slump number, the more liquid/water is in the mixed concrete, and
the easier it will be to place the concrete (completely fill the
excavation.) Too low a slump and it will give you a weaker mix, per the
above (and other) URLs.
In the case of my Trylon tower, 3,000 pound mix was the minimum spec'd
for the foundation. I asked for 3,500 pound mix; the trucker's receipt
claimed that's what he delivered off his truck. This same receipt said my
mix was a four inch slump. Not as soupy as five inch slump would be, but
still easy enough to place and work.
Hope this helps.
73 de
Gene Smar AD3F
P.S. Ain't towers fun?
----- Original Message -----
From: "Jerry Keller" <k3bz@arrl.net>
To: "(Reflector) TowerTalk" <towertalk@contesting.com>
Sent: Thursday, May 29, 2003 12:08 PM
Subject: [TowerTalk] Concrete "Slump"
> Following advice received here (thanks!), I had the concrete guy here
today
> to advise on my site for a 5' x 5' x 6' deep base pour. He asked if I
wanted
> "3000 Lb. concrete". And he asked if I wanted a "5 inch slump". I told
him
> I'd get back to him. What do these terms mean? What should I want?
> Jerry K3BZ
>
> _______________________________________________
>
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