[TowerTalk] concrete forms

[Jim Lux]

At 08:23 AM 7/31/2006, ADRIAN REES wrote:
>Hi Guys
>Over here in the UK, I am about to "plant" 4 towers, and pour C35 Grade 
>Concrete in the bases. Anyone know what is the setting time for this 
>stuff, and can it poured in one or two lots ? Getting this amount of 
>concrete onto the site is not easy. I live up a mountain, with access 
>limited to 4 Wheel Drive vehicles, and certainly a Truck will be near 
>impossible to get on site, let alone a Ready Mix Concrete one ! So I may 
>have to mix on site, and pour in batches.
>

You'll want to talk to your concrete supplier.

The "set time" for the concrete can be adjusted to a certain extent (they 
do this anyway to compensate for temperature changes.. it's a chemical 
reaction, and if you used summer mix concrete in winter, it'll take forever 
to cure..)  Mind you, this is for "largish" jobs.  The local U-kart place 
probably doesn't do this.

My experience (which is limited) has been that if you have a 2 or 3 hour 
gap between batches, there's a definite non-joining, because the first pour 
has already started to set.. it's certainly not a monolithic block.

Obviously, a big monolithic block is better, but the real question is how 
do you get multiple pours to join in a mechanically sound way. There might 
be some clever way to, for instance, have interlocking grooves, or rebar 
links, etc.


Jim, W6RMK