[TowerTalk] Cadweld vs other welds or brazing

[Roger (K8RI) on TT]

On 5/2/2014 9:04 PM, N3AE wrote:
> I've been following this thread with interest.
>
> What's the proper way to bond galvanized steel anchor rods to the rebar cage to get a good Ufer ground? The UST specs specifically state not to weld the rebar (because they call out ASTM A-615 rebar, not the weldable A-706).

This makes me wonder why is rebar tied? It adds little strength. The 
wire is soft iron and basically holds the rebar in place.  Now I can 
understand tying rebar over wide areas lice floors and concrete aprons.  
It's easier, anyone can be taught to do it in a few minutes, and you 
don't need a certified welder with cables and equipment all over the 
place.  IOW: It saves time and a whale of a lot of money.  Yes, I know 
it's in the code, but why?

If all the wire does is hold the rebar in place during the pour, 
wouldn't it work as well with out the wire (if you could get it to stay 
in place during the pour. It's my understanding that the rerod just 
keeps the concrete together. Is that correct?

If you are worried about electrical, "I would think" all that wire wrap 
should be sufficient.  In most cages there are many wrapped connection  
I hve 9, wire-wrapped connections, and well over 30 tack welded 
connections that I hope are sufficient to hold the shape while moving, 
placing, and pouring.  All reinforced by wire wraps.
>
> My plan is to use bronze rebar ground clamps rated for direct burial for both the wire-tied rebar cage and the anchor rod connections, with #4 AWG solid copper wire between them and a bit of stainless shim stock between the clamps and the galvanized anchor rods (for the dissimilar metals problem - galvanized with copper-bronze clamps). All the above encapsulated in the concrete pour.

I'm not an engineer, but "I would think" that if the pour is good, you 
wouldn't need "direct burial" connections.
"I think", in general, in ham installations most of this is way over 
kill...That's ignoring some of the "HUGE" installations around the 
country that are in the many kilo buck, or even mega buck range.  Oh how 
I wish I had room for this 
http://www.rogerhalstead.com/ham_files/skyhook.htm  .  John passed away 
just a few years after completing it. It contained thee tractor trailer 
loads of steel. It was on e-bay with no reserves. Not one bid  It was 
finally taken down by a company for scrap.  I know how much that cost 
and it was a bunch, even back then when steel was a third of today's 
cost.  20 years later, I used to buy 2 and 3" structural steel tube, 
1/2, 3/4 and 1" square tube of various wall thicknesses, 2, 3. and 4" 
DOM hundreds of pounds at a time.  Now I measure, calculate twice, 
measure again and then buy with maybe a couple trips back to get what I 
need.  I used to buy stacks of 6061-T5 1.5", 2", and 3" of various wall 
thicknesses.   I'm careful to measure to get the most pieces out of a 
standard 24' length of what I have left.  The last time I bought steel, 
I thought they had charged me for Aluminum.

One thing I have learned is to make the mix rich enough to cure all the 
way through.  At least that's what the contractor tells me and he 
doesn't get paid for that.  Kickbacks?  Don't know.

73

Roger (K8RI)


> Make sense? Are the SS shims overkill or even undesirable (compromise the tightness of the connection to the anchor rods)?
>
> Shawn - N3AE
>
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