[TowerTalk] Tack welding rebar, need howto

Patrick Greenlee patrick_g at windstream.net
Fri Jan 3 21:55:43 EST 2014

When welding the ends of pieces of rebar as an alternative to a slight 
overlap and wire tying it just doesn't matter what the alloy is if you can 
stick it together good enough to not fall apart when pouring the concrete 
you have met the requirement.  This is not a big deal structural issue. 
Crazy glue (alpha cyanoacrylate anaerobic adhesive) would be fine if it 
would hold during the pour. Also kite string, dental floss etc.

Patrick NJ5G

-----Original Message----- 
From: David Gilbert
Sent: Friday, January 03, 2014 6:34 PM
To: towertalk at contesting.com
Subject: Re: [TowerTalk] Tack welding rebar, need howto

Well, my point with the cheap stuff is that you don't really know what
you're welding to.  It might be part cast iron from an old engine block
for all I know, and that doesn't weld well at all.  You wouldn't
necessarily be able to tell if you had a good joint or not.   I used a
LOT of 60,000 PSI rebar when I built my house (ICF walls and 4,500 sq ft
of slab) and I was surprised how much variation there was in brittleness
when I bent it even for the supposedly good stuff.

But no, I'm not really hung up on the strength of the steel itself. All
of it is stronger in tension than the concrete is, and if I'm in doubt I
just use more of it.   ;)  I only mentioned it because I thought I saw
someone earlier in the thread question whether a welded cage was needed
for strength.

Dave   AB7E

On 1/3/2014 3:13 PM, Jim Lux wrote:
> On 1/3/14 12:05 PM, David Gilbert wrote:
>> By the way, while I totally understand why you'd want to tack weld the
>> bolts to the rebar, I've never thought much of welded rebar cages in
>> general.  True weldable rebar (the stuff that is supposed to hold it's
>> strength after welding) is expensive and harder to get.  The 40,000 PSI
>> stuff you can get at Lowes and Home Depot comes from indeterminate
>> source material (a mixture of washing machine chassis, old bed springs,
>> car frames, salvaged rebar, etc) and almost certainly will not weld with
>> consistent strength, although you can buy better 60,000 PSI stuff from
>> construction supply places.
> Yeah, but if you're using rebar from who knows what kind of metal, are
> you really concerned about whether it retains the strength when you
> weld it?
> As I recall, about as weak as steel gets is 30-40 ksi.. Unless your
> welding physically damages the steel, I don't know how much lower you
> can go.
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