Hi Scott,
First off, I am NOT a concret engineer. Just a ham who likes to read.
My advice would be to get a copy of an Army Technical Manual TM 5-742,
Concrete and Masonry. It tells you everything you need to know in this
area. Uncle Sam spares no expense in this area. Another TM 5-615 covers
concrete and masonry for repairs and utilities.
I bought mine from the local gov't printing office about 8 years ago for
$5.00 ea.
Page 3-3 and 3-4 give the age compressive strength relationships for types I
and III air-entrained and non-air-entrained portland cement.
In areas subject to freezing and thawing you need to use air-entrained
cement and recommended for all paving applications regardless of weather.
Given that, age-compressive strenght for type IIIA and IA are about the same
and vary from around 5000 lb. per sq. in for a 5 gal water per sack of
cement to 3000 lb per sq in for a 7 gal water per sack of cement. These are
the strengths after 28 day with a 70 degree F cure time.
You should also be asked the number of bag mix for any given order, that
being 4 bag, 5.5 bag or 7 bag. The seven bag mix if by far the most durable
and shows little sign of weathering after 5 years of exposure to a sulfate
soil.
For my 4' x 4' x 7' base with anchor bolts, I specified an air-entrained 7
bag mix that was dry... It looks as good as the year poured. I have a US
Tower monopole specially made for 18 sq foot of antenna at 55 foot height
for 70 Mph winds.
73, George
K8BRW
----- Original Message -----
From: "Scott & Sherry Souva" <ssouva@twcny.rr.com>
To: <towertalk@contesting.com>
Sent: Monday, March 19, 2001 5:16 PM
Subject: [TowerTalk] Concrete Strength
> TT list,
>
> I am putting up a US Tower TX-455 in about 4-6 weeks. When I priced the
> concrete delivery, the first question was; "What strength do you want?"
> Examples given were 1500 lb., 2000 lb., etc. I asked a US Tower
> representative, but they didn't know. Any recommendations from the list
> would greatly be appreciated.
>
> 73 de KG2S,
>
> Scott Souva
> ssouva@twcny.rr.com
>
>
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