I think you guys are missing the question....
For self supporting towers, I have seen poured a relatively thin slab
which is very long and wide...after it is cured a secondary pour is made
atop the other after a form is constructed and a smaller in square are
pour is made - but it is usually taller.
Imagine the first pour is a copy of the ARRL Handbook....it sets... a
form is then constructed on top of it which creates a pour that looks
like a W4 wattmeter....
Both pours are reinforced concrete with rebar cages and there is a
common set of rods left sticking up in the center of the intial pour
which then has a form made about it and that pour made....
When 160 enthusiast W3IN moved to the East Coast of Florida years ago
he had time to erect - though not fully energized before his passuing -
a large self supporting tower which was very wide at the base AND, IF
MEMORY SERVES - roughly a hundred foot tall... he used this technique -
the initial pour is kind like a wide footprint and the secondary pour is
plain old weight.
k4oj
Richard Karlquist wrote:
>> It should be in one pour so that the base is totally
>>bonded together. If
>>the bottom pour has 'gone off' and hardened, you wind up
>>with two separate
>>layers.
>>
>> Sometimes there are two pours if you have to have two
>>trucks worth of
>>concrete but they are poured consecutively with little or
>>no time delay.
>>
>>
>
>So how much delay is tolerable? It takes me 20-45 minutes
>to drive back to the ready mix place 1 1/2 miles away,
>get reloaded, and drive back. After 45 minutes, I can
>at least poke a hole in the previously poured cement
>with a stick. Is this good enough? Is it helpful to
>sprinkle a little water on the top to slow down the
>curing before the next pour? Always wondered about this
>stuff. It is sn't covered in any concrete books I've read :-)
>
>
>Rick Karlquist N6RK
>richard@karlquist.com
>www.n6rk.com
>www.karlquist.com
>_______________________________________________
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>See http://www.mscomputer.com
>
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>
>
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