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
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.
Gene Smar AD3F
P.S. Ain't towers fun?
----- Original Message -----
From: "Jerry Keller" <firstname.lastname@example.org>
To: "(Reflector) TowerTalk" <email@example.com>
Sent: Thursday, May 29, 2003 12:08 PM
Subject: [TowerTalk] Concrete "Slump"
> Following advice received here (thanks!), I had the concrete guy here
> to advise on my site for a 5' x 5' x 6' deep base pour. He asked if I
> "3000 Lb. concrete". And he asked if I wanted a "5 inch slump". I told
> I'd get back to him. What do these terms mean? What should I want?
> Jerry K3BZ
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
> TowerTalk mailing list