[TowerTalk] New Tower Construction - Questions

[K7LXC@aol.com]

In a message dated 08/30/2000 2:42:27 PM Pacific Daylight Time, 
aa4lr@radio.org writes:

> * I'm planning to embed a Rohn 25 tower section in the concrete base. I'm 
>  unsure if direct contact with the concrete will cause corrosion of the 
>  section. Should embedded tower sections be coated with some kind of 
>  protectant? Or would a protectant reduce the mechanical coupling between 
>  the base and the tower? Is corrosion (other than pooling of water in the 
>  legs due to improper drainage) not really a problem?

    Most everyone just sinks the section in the concrete as is. OTOH W3LPL 
had serious corrosion problems by doing that. Now he coats metal surfaces 
that'll be in the concrete with building tar. That might be a 
'belt-and-suspenders' approach but it'll sure take care of any potential 
longterm problems. 
>  
>  * I know I need a rebar cage in the base, but I'm fuzzy on the details of 
>  how to construct it. This is a standard 2x2x4 foot base, and I understand 
>  the rebar should be about 3" from the edges of the concrete. This 
>  translates into a 1.5x1.5x3.5 foot cage. I can see rebar at all the 
>  edges, how much is needed on the long faces? Are there horizontal pieces 
>  on the way down each face? Spaced how often? How about spacing for 
>  vertical pieces? Are there pieces on the top and bottom faces? Are there 
>  any pieces on the INTERIOR of the cage? Isn't there a problem with rebar 
>  and tower section trying to occupy the same space with the interior 
>  elements?
>  
    You can add any rebar that you want - the specs are for the MINIMUM size 
and amount. If you want to add vertical pieces to hold everything in place or 
additional horizontals - go nuts.  

>  * I plan to build a small wooden form to shape the top few inches of the 
>  concrete base. Is there something you can put on wooden surfaces to make 
>  the concrete not stick to it? This would make it easier to remove the 
>  forms later. 
>  
    You can cover the parts of your wooden form that'll touch the concrete 
with motor oil. The forms will come off easily and the motor oil won't affect 
anything. 

Cheers & GL!   Steve    K7LXC

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