[TowerTalk] Tack welding rebar, need howto

[Jim Lux]

On 1/3/14 4:34 PM, David Gilbert wrote:
>
> 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.
>

I think, as someone pointed out earlier, the welding or tying is more 
about making sure the rebar stays reasonably in place when they dump the 
concrete in.

Nah.. not cast iron (it's hard to roll into the bars).. probably old 
ships run up on the beach in Bangladesh or India

http://www.slate.com/blogs/atlas_obscura/2013/10/02/dirty_dangerous_and_deadly_the_shipbreaking_yards_of_bangladesh.html

http://en.wikipedia.org/wiki/Alang

talk about hard manual work.. These guys resharpen their used hacksaw 
blades.

I don't know if they chop the steel into "quasi-billets" and then roll 
them into rebar, or if they melt it all down and then roll from there.

I suspect that however it's made, the vast majority of the stuff has 
fairly casual metallurgical analysis: It rusts, it's roughly the right 
weight for the size, it must be mostly iron.  Details about carbon 
content and heat treatment are probably not of great concern<grin>.