[TowerTalk] RE: Erecting tower

[Dino Darling]

For those who may not know....

I wanted to point out what vibrating concrete does.  It PECULATES the air 
pockets or VOIDS out of the pour (see below).  Voids will cause weak spots 
in the base!  If you OVER-VIBRATE the pour, the aggregate (rocks) will sink 
to the bottom of the pour and you lose the STRENGTH those rocks 
provide.  Don't pour the entire base and then vibrate.  Vibrate as you 
go!  It tough for air to work its way up 6' of concrete if its thick (low 
slump).  When you see no more bubbles coming up, STOP!  Plunge the vibrator 
in and out of the pour as you go.

Also, don't let the head come out of the pour or you'll have concrete 
splashed EVERYWHERE!  Its like a mixer coming out of cake mix!

>Remember to have a crew member move around the concrete as it's being 
>poured or rent an electric vibrator to remove the air pockets that may 
>develop as the concrete tries to flow around the tower braces.  Don't over 
>vibrate it though.

Dino...k6rix at earthlink.net