[TowerTalk] Nube rebar question

[Gene Smar]

Kent:
 
     There are a couple of things folks do to keep the ends of rebar off the dirt at the bottom of excavations.  One is to purchase commercial blocks that have tie wires built in.  The name escapes me at the moment (gents?)  You would tie these to the bottoms of a couple/several bars on each side of the rebar cage.  The poured concrete envelopes these blocks and they become part of the structure.
 
     An alternative that I chose is simply to put regular bricks underneath a couple/several of the bars and let the cage sit atop the bricks prior to the pour.  Here's a link to a photo of the bottom of my tower's hole:  http://tinyurl.com/logoxop .  You might be able to see a couple of the light-gray brick at the top of the photo.  If you go this way, make sure that the cage doesn't get pushed off the bricks when you pour the mix into the hole.  I managed to keep the cage motionless by tieing the top few bars to the wooden form for the crown, which you can see in the photo.  While the mix is being poured you can cut these cage support wires off the rebar and pull them out when the mix gets up to within a couple of inches of the wires.  Don't wait until all the concrete has been poured before you cut the wires.  If you were to do that, you'd end up with iron wires sticking out of the concrete.  When (not if) these wires corrode, you'll have a nice path into the top of the concrete block for water to infiltrate and freeze/crack. 
 
GL es 73 de
Gene Smar  AD3F
 
 



On 12/16/14, Kent Olsen wrote:

I have never worked with rebar or concrete but it seem fairly strait
forward in building the cage and pouring the concrete. I have read the the
rebar cannot be with in 3" of the dirt or it will rust and fall apart. What
do you do in the bottom where the rebar sits on the dirt? Is this just a
sacrificial bit?

Thanks
73
Kent
K6DKO
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