Messin With Some Rebar

[timiacobucci]

Messed around with some rebar today. I had #4 = 1/2" and #5 = 5/8". I coiled a 48" piece of the 1/2" 3 times, tried to fish it at the end but it was waaay too springy, I could cross them good but they came back to where you see in the picture.

#4 Rebar Coil

Then I tried some shorter bends. 16" first then 14". I like the 16", that is a good show size for me I think. The 14" was a bit harder overall than normal 1/2" hrs I feel. The crush is a good bit springier and stronger, the kink is about the same or a bit harder.

#4 Rebar

Then I tried the 5/8", I only had the one piece and I knew I should have started with a longer piece like 30". But I am usually conservative and it always leaves me wondering so I thought I would see what David's 26" bend feels like. I didn't really expect to finish it. I did get a good bend in it though. I am still sick and was hacking a terrible cough between each hit on it. With some rest and isos I think I might get it before too long.

Also I don't know what the markings on rebar really mean, I have a close up picture of the stuff forged into the side of the 5/8" bar.

#5 rebar x 26"

In case the picture is unclear, it says

M / 5 / S 60 / Dominican / Rep

I can guess what the last part means, the 5 I think means #5 which is 5/8". Does the 60 mean it is grade 60? It didn't feel very springy so I am pretty sure it is grade 40.

This brings up another question though, how do you measure rebar really? The way it is formed there are ridges around it and a seam that is much thicker than the base diameter down 2 sides. I took pictures of the 3 measures on the #4.

Measure 1

Measure 2

Measure 3

[pawel r]

[Tim71]

Tim,

I posted a guide to rebar in your "braced bending in the teeth" thread which will tell you what all those markings mean.

Basically, #5 rebar means that a round bar of 5/8 inch, would be the same weight per inch as the #5 rebar. Sorta means it's 5/8 on one hand but as you say, it's not perfectly round.

The grade 60 I have is super springy.

Your #4 rebar is definately grade 40 I can tell you that. Loads up on the crush doesn't it? I may test a piece in a vise sometime and see if it can break because it kinda worried me.

Great job BTW on some awsesome bends!

Tim

[timiacobucci]

Thanks Tim. I did read that link you posted before and I even found some others that sort of helped but sort of confused me more as well. From just reading that stuff it seems the S60 should mean it is grade 60. Do you have any opinion on the meaning of that particular part of the marking?

Ya I was really surprised how hard that 14" bend got towards the end, if the big one is grade 60 it is gonna be killer to try and crush it. I will try and get a longer piece soon and see how the rest of the bend is, sometimes it's hard to tell how springy a bend is just from the start.

[Paul Knight]

Cool stuff - where do you go to get rebar? and the one time I've played w/it at casey's (he had a rusty peice he must have gotten from work) - it was super springy! wwaaaaayyyy springy! Is that what trying to bend long bar stuff w/CRS is like?

[vikingsrule92]

Cool stuff - where do you go to get rebar? and the one time I've played w/it at casey's (he had a rusty peice he must have gotten from work) - it was super springy! wwaaaaayyyy springy! Is that what trying to bend long bar stuff w/CRS is like?

That was probably G60, and yes thats what long bar with CRS/Stainless is like from what I've heard. You can get G40, which is like HRS basically at a steel supplier and I think also at Lowes or whatever.

[timiacobucci]

Well it sounds like you got some grade 60. There is that and 40. This is basically the different minimum yield strength ratings for the grades.

Grade 40 is 40kpsi and is a bit stronger than normal a36 hrs which is something like 36 kpsi mininum yeild. It is probably a bit tempered or cold worked to bring it up some which makes it a bit tougher and a bit springy on the crush compared to normal hrs.

Grade 60 is the #5 or 5/8" bar I got. I got some more today (at home depot to answer your quesiton). And cut it longer at 30" and 32". It only got worse the more I could bend it.

Grade 60 #5 Rebar

I had that 32" in a perfect position to hip pull it but my hand was messed up and I didn't want to rip my big blood blister open. I think I might be able to finish that one soon when my hand heals a bit.

Blood Blister Under Callus

I gotta work this week and that would suck.

The sweep and crush on the hrs long bars I have done was the easiest part. This thing was a nightmare. The kink started like strong hrs but the crush feels close to crs. I have not done any really big crs bars, 1/2" is the biggest but the amount of spring and the way the strength ramps up feel very similar.

So grade 60 is a whole different game. 60 kpsi. Most commonly available cold rolled steels are in the 50 - 60 kpsi range. The cold working tempers the steel, the 60 kpsi yeild for the rebar is only attainable through tempering, this is what makes it springy as well as much stronger.

[tja]

Those rebars look nasty. Good work!

[Tim71]

Tim,

Do keep in mind too that rebar as with all steel that is the MINIMUM yield rating. Since rebar is made from alot of left-over garbage in steel terms and is made in alot of different countrys, some will be crazy hard. I had a grade 60 #5 at 5 feet and to prove to the steel supplier that it was really grade 60, I put one end on the ground and one end on the bumper of my truck and bounced up and down on it with my 190 lbs weight. Didn't bend it. It was like a crazy trampoline I kid you not.

That 5 foot piece was a fairly rough braced bend even over the knee.

Tim