Dowel Bar Placement

[abusementpark]

A lot of times when we have L-shaped slab-to-grade beam dowel bars, the contractors prefer to "wet-stick" them during the grade beam pour, instead of the tying them to the grade beam rebar before the pour.

Is there any reduction in dowel capacity that should be taken if the dowel bars are placed in this manner? Does ACI comment on the matter? Any help would be greatly appreciated. Thanks.

 

[Ron]

There was another thread on this a while back. ACI 318, Section 7.5 requires that reinforcing steel be in place and adequately supported/tied PRIOR to concrete placement.

Wet sticking is not a good practice. Bond can be severely compromised.

 

[JAE]

thread167-53815

thread507-244716

 

[asixth]

I also notice contractors placing starter bars into wet concrete instead of tying them to grade beam reinforcement.

 

[doka1]

If its simply the bars to be bent down into the slab I dont see a problem if its done in a timely fashion. As contractor you have to make a judgement based on the spacing and whether or not the alignment is critical. Just would have to make sure there is not too much congestion in with the grade beam rebar. A good contractor would have a template for the bars to rest on while the concrete hardens, otherwise it may be hard for the bars to stand in place. A good example when it is acceptable to wet stick is when bars extend from the top of a foundation wall into the slab. We always wet stick these bars otherwise placing and finishing concrete in the wall becomes very difficult and even dangerous.

Dont misunderstand me though, wall dowels in a footing should always be tied before placement. I am just trying to point out that there instances it is acceptable to wet stick.

 

[JAE]

I don't think there are any instances where it is acceptable to wet stick. ACI doesn't condone it at all.

The dowels from a top of foundation to a slab could be very critical bars necessary for the structure to perform as intended. By wet sticking you are ensuring that you won't know at all what sort of development you have in the bars.

I know wet sticking occurs, but it is never acceptable in my book.

 

[Ron]

Piling on here...I agree with JAE...it is not an acceptable practice. Keep in mind that if some type of failure occurs, it won't matter whether it was the cause of the failure or not...it just indicates that your practices are poor and that concept will be extended to all your construction. It's hard to defend an unacceptable practice.

 

[Zambo]

Well Ron piling on a bit but.... I've worked for contractors for over 20 years and I also don't see advantages for "wet sticking".

For me the main disadvantage is that you're mixing up the trades, steelfixers fix rebar and masons place concrete. Of course we have all had cases where a few starter bars are out of position and we have to find a solution. But is there really any evidence that "wet sticking" avoids this problem.

 

[ToadJones]

Just laziness on the part of the contractor.

 

[BAretired]

Whether or not there are advantages to wet-sticking, it is not an acceptable practice and should not be permitted.

BA

 

[abusementpark]

Thanks for the responses. It certainly seems tough to justify allowing it if ACI clearly does not condone it.

Does anyone know if the the masonry code address this issue? Wet sticking is also commonly done for masonry wall reinforcement splices during grout pours.

 

[engrbon]

Wet-sticking nice term. It usually happens been to several places already and seen their construction practices. Sometime s it gets you thinking where did they get this idea.

But I agree with Sir Ron that it's difficult to defend unacceptable practices when worst comes to worst.

 

[PMR06]

Has anyone ever seen a failure or problem due to bars being "wet-sticked"?

I'm not defending the practice, but wondering how big a problem this really is? I know it is done all the time. With so many instances, shouldn't there be many examples of problems?

 

[engrbon]

Have seen several times the bars are not properly bonded with the concrete probably they sticked it a li'l bit late.

 

[BAretired]

I have never seen a failure resulting from wet-sticking because the practice is usually confined to dowels which are not under much stress...i.e. dowels from a footing to a foundation wall. If the practice were used in highly stressed reinforcement, the experience could be different.

Theoretically, wet-sticking could be done so that proper bond is achieved between steel and concrete. The problem is that the inspector cannot tell after the fact what technique was used and hence how good the bond is.

BA

 

[JAE]

I've seen loose dowels in hardened concrete - wiggled easily when touched.

 

[msquared48]

Probably placed when the concrete had partially set so that the concrete matrix could not flow evenly to the bar as with totally wet concrete. I have seen the same thing over the years.

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

 

[BAretired]

If the bars were loose in the holes and wiggled easily when touched, one would not expect to be able to develop much tension in the bars but they may be effective in providing a key of sorts.

BA

 

[msquared48]

Yea - a key that the bars were an after thought of a contractor with a hangover.

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

 

[doka1]

I knew people would disagree with me. What I will admit is that it does make the inspection process harder. How can an inspector verify embedment lengths and the state in which the concrete was in when they were placed.

In my typical example you are dealing with bars that have to bend down to slabs. I cant tell you how many times i see rebar detailers draw this bar being being bent before concrete placement. As if we are going to knotch our forms for every foot on center. Similiarly, when you are placing a 12" wall and half rebar sticking up 3' past the pour it makes it a nightmare for the pump operator or the guys and the operator on the bucket (cant lower bucket as rods are in the way). Now if you have someone right after the wall is being topped off wet stick staight bars into the pour, is someone here going to say there is a problem with that?