Driving rebar into an existing wall

[MacMoose]

Dealing with a situation where a bunch of dowels into the top of a concrete parapet wall were left out. Contractors solution (no, he didn't ask first) was to drill 3/4" diameter holes into the top of the wall and pound #6 rebar into the holes, some centered only a couple of inches from the edge of the concrete. My feeling is that this is a very bad idea, but after dilegent research I can come up with nothing solid (codes, research)to back my opinion up. Any thoughts, information or research out there on this topic? Thanks.

 

[OHIOMatt]

It is a bad idea. Instead of wasting your time trying to prove that what he did was wrong, simply have him provide the data supported by codes and research were it is allowed.

He will not find it.

 

[bridgebuster]

Ditto Bad Idea (but you can't blame a contractor for trying). Depending on your sitution, it could fall under ACI 318 Appendix D.

 

[dcarr82775]

I would never have thought of this. You have to give him credit for thinking outside the box.

No I wouldn't accept it. Make him provide data supporting this method. I suspect there is none so then he can do pull tests on the bar, which he pays for of course. Or he can just replace them in some approved manner. When I bring up testing the contractor generally backs off because he knows what he did isn't going to work.

 

[SteelPE]

For some reason I just am not getting your detail.

Do these bars run along the entire length of the wall ("A") or do the protrude from the top of the wall ("B").

I find it hard to believe the contractor would drill a hole the entire length of the wall as show in "A"..... but I wouldn't put it past one.

 

[ToadJones]

ahh, he drove rebars into drilled holes?
what is bonding the bars to the concrete?

 

[SteelPE]

I'm wondering if they used epoxy when setting the bars... which would be acceptable under the right circumstances.

 

[Teguci]

He might find this instructive for the next time he wants to hammer rebar into cured concrete.

Yeah, I do blame the contractor for trying. Had a cantilevered retaining wall detailed with hooked bars into the footing (clearly called out on the drawing). Showed up on site to find that the contractor had laid straight bar for the tail of the hook and pushed vertical bars into the soil at the end of horizontal straight bar.

 

[Ron]

Not acceptable. No development strength, no uplift capacity.

 

[TXStructural]

ACI 318 Appendix D would control, regardless of the circumstance or method of installing the dowels. Adhesive would be the preferred method. The proposed method would not be acceptable since the mechanism by which rebar bonds with concrete is almost entirely through the deformations, which would be swaged away in the driving process.

 

[wannabeSE]

I just have to ask. What is the purpose of the dowels in the top of the parapet? Or, are the dowels in the top of a wall where a parapet is going to be placed?

 

[csd72]

wannabeEIT,

wow, all these strong opinions and you are the first one to actually ask what these dowels are for!

 

[dcarr82775]

csd72,

If I called for dowels and they were installed in the manner described, I don't care what they are doing, I am not accepting them.

 

[PMR06]

I've seen dowels installed in this manner that really were for shear across a joint so in a way they were like slip dowels.

Here's the real question though: What did the drawings say to do? Were they supposed to be lapped with the previous bars, drill & epoxied, called out with no instruction or omitted?

 

[Guest102023]

Teguci,
LOL.
My own mental image was more along the lines of Tinker Toys.