Replacing hooked end of a rebar

[JoeBaseplate]

Please see the attached sketch. This is for a concrete renovation job where some concrete is spalling due to rebar corrosion. We have a few spots where the hooked end of a horizontal rebar has corroded and need to be replaced. The question is how do we make replace this bar. My solution is to drill next to the horizontal portion of this bar, and install a hooked dowel with Hilti HIT adhesive. This would decrease the depth of the required lap of the new and existing horizontal lengths. Does this sound like a reasonable solution? Any input would be greatly appreciated. Thanks,

 

[Lion06]

I don't think epoxy will decrease the required lap length.

Are you demo'ing any of the concrete?

 

[rapt]

Lion06,

Agree with you. The lap length is not reduced. Also, what is the fire rating of the epoxy?

 

[JoeBaseplate]

Lion,

We are demoing the vertical face (@ hooked end) of concrete.

 

[msquared48]

I trust you have determined what caused the rebar to corrode in the first place and solved the problem?

If there are several isolated bars separated by a large distance, say four feet or morem I would just remove the corrosion and forget about it.

However, if there are several concentrated in a specific location, a more likely scenario, I would consider sawcutting in new slots for corner bars, not cutting any transverse steel, and epoxy in new corner bars.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[Lion06]

If you are demo'ing the vertical face, why not cut off the bars where they are no longer corroded and use mechanical couplers to put back exactly what you're taking away?

 

[ishvaaag]

It seems reasonable to me.

 

[ishvaaag]

Not the splice, err, the way of proceeding.

 

[ishvaaag]

To make it clear, through the splice you basically restore the configuration. Hence you need a splice that fits the case, then normally a straight parallel splice (once eliminated the corroded hook part), so normal splice length.

 

[msquared48]

Lion:

I considered that too, but threading the rebar in place for the couplers, plus providing adequate concrete cover for couplers of a diameter larger than the bars they are joining would be a problem.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[bones206]

These couplers seem to fit the bill:

http://www.erico.com/products/LENTON_LOCK.asp

No bar end prep and not as bulky as other couplers.

 

[csd72]

can you get any stub ends that fit onto the end rather than a coupler.

Not sure what they are called and my current connection is too slow to google it but there are couplers out there that form a stub end anchor that develops the full strength of the rebar.

 

[hokie66]

How do you know that the bar has to be replaced? Maybe it is superfluous.

 

[JoeBaseplate]

Placing a coupler would be problematic as the clear cover would be compromised.

As to why the rebar has to be replaced, there are some areas where the rebar has some corrosion and my concern is that even if its cleaned and patched back, it will corrode again.

Attached is an typical example of a rebar corrosion. Our typical detail says that if rebar section loss is more then 10%. then rebar has to replaced.

 

[hokie66]

I was asking whether or not the bar is required. You may not be in a position to determine that, but there are many instances where typical details require bars to have cogged ends where they really serve no purpose. The tails of these bars lying against the formwork is a common reason for corrosion. If the bar can be shown to be not required and can be simply cut off, that is a better result for corrosion protection.

 

[csd72]

hokie makes a good point, if the hooks are there purely for serviceability reasons then you may be able to do without them since most of your shrinkage would have already occurred.

The type of thing i was talking about is as follows, not sure if there is a version out there that can be clamped rather than screwed on.

http://www.erico.com/products/Terminator.asp