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-   -   vibrating concrete externally via the forms (http://www.diychatroom.com/f105/vibrating-concrete-externally-via-forms-148617/)

DIY1 06-29-2012 01:54 PM

vibrating concrete externally via the forms
 
I know this is a pretty broad question, but what will happen if instead of internally vibrating my soon-to-be-freshly-poured ~8' foundation walls for my home addition, I externally vibrate the forms?

I've read that external vibration isn't as good as internal vibration, but are we just talking the external finish of the concrete once the forms are removed or are we talking structural/strength issues?

My concrete guy, who is doing my foundation as a side job (and who did his own home foundation without internal vibration in his foundation walls) is planning to go the external vibration route on my project and I just want to make sure that's not dangerous.

Canarywood1 06-29-2012 02:44 PM

Quote:

Originally Posted by DIY1 (Post 954085)
I know this is a pretty broad question, but what will happen if instead of internally vibrating my soon-to-be-freshly-poured ~8' foundation walls for my home addition, I externally vibrate the forms?

I've read that external vibration isn't as good as internal vibration, but are we just talking the external finish of the concrete once the forms are removed or are we talking structural/strength issues?

My concrete guy, who is doing my foundation as a side job (and who did his own home foundation without internal vibration in his foundation walls) is planning to go the external vibration route on my project and I just want to make sure that's not dangerous.


It all depends on the slump of the concrete that your placing,the lower the slump the more vibration is needed,higher the slump the less,and maybe no vibration is needed,there is such a thing as overdoing it,and you can do more harm than good,what is he using as an external vibrator and why?

Msradell 06-29-2012 07:39 PM

There are two risks associated with external vibration. The first obviously is the stress it puts on the forms raising the potential for them to fail. The second and less obvious is that the concrete may not completely fill the voids around the rebar and thus weaken the wall in the long term. It probably won't effect anything for your project but internal vibration is the norm.

TRUEPRO 06-30-2012 09:15 AM

Just place the concrete with a good soft slump. Why in the world would anyone ever vibrate a footer? Huge waste of time.

Msradell 06-30-2012 09:53 AM

Quote:

Originally Posted by TRUEPRO (Post 954626)
Just place the concrete with a good soft slump. Why in the world would anyone ever vibrate a footer? Huge waste of time.

He's not pouring footers, as stated in the OP, he's pouring 8' walls!

TRUEPRO 06-30-2012 10:20 AM

Ya i misread it. So i take it these walls will be in the basement And their being placed on a footer? Or is a monolithic?

FYI- You dont "pour" concrete. You place it. You POUR water out of a bucket.

CopperClad 06-30-2012 11:01 AM

Uh.. I've mixed many batches of concrete in buckets/wheelbarrows and poured it in a hole.. I should have been placing it there all these years! Thanks !! :thumbsup:

TRUEPRO 06-30-2012 11:23 AM

Quote:

Originally Posted by CopperClad (Post 954711)
Uh.. I've mixed many batches of concrete in buckets/wheelbarrows and poured it in a hole.. I should have been placing it there all these years! Thanks !! :thumbsup:

Lol not that it matters either way just a technical indifference. Pour/place/dump/splash yayaya

But for the sake of my old Commercial concrete foreman, We shall PLACE the concrete.

Kinda like .... were not gonna lay tile, were going to SET tile.

Were not gonna set brick, were gonna lay brick.

Concrete def gets placed. Not poured.

Msradell 06-30-2012 12:20 PM

The placing concrete vs. pouring concrete discussion has been around for a long time! :yes: There are definitely people on both sides of the discussion. I've always used the word placing when doing flat work and the word pouring when doing form work such as walls or columns but that's just my terminology. I really don't think there's any right or wrong answer to the question.

TRUEPRO 06-30-2012 12:28 PM

Thats funny you say that because i was thinking if i had to to label it, i would say "pouring" COULD be said for flat work since its all horizontal and anything you POUR will lay flat and "PLACING" for vertical work since you cant pour water in the sky. You "Place" the mud in a strategic position after you build calculated forms. Hmm....

Now, my commercial pool builder agrees with you. He says he places the ground and pours the forms. But that just seems completely backwards. 2 against 1 here so i better have a good argument.

Pour=on the ground Place=in the sky

concretemasonry 06-30-2012 12:51 PM

Vibrating the form can give a smoother surface and can even hide "honeycombing" or other errors in placement.

Vibrating the concrete internally gets a better bond and insures that the rebar does its part of the job.

Dick

CopperClad 06-30-2012 12:51 PM

LOL ! I pour concrete IN forms.. I PLACE mortar under blocks. haha!:thumbsup:

Mort 06-30-2012 05:31 PM

As far as vibrating goes (like the thread was supposed to be about), I've always seen it done internally. On a foundation wall, its more important that it get around the steel than it is to have a few rock pockets here and there. Just smack the forms with a hammer, and that'll take care of most of it. Of course, a lot of foundation crews like the concrete so wet that no vibration is necessary, but as a former QC guy, it makes me cringe.

And I usually say "pour" because that's how I was taught, but when I'm talking to concrete elitists (apparently, there is such a thing), I say "place." An inspector I was talking to once had an old boss that told him to always write "place" in his reports, because if you "pour" it, that means it was too wet.

jomama45 07-01-2012 11:12 AM

Quote:

Originally Posted by Mort (Post 954936)
As far as vibrating goes (like the thread was supposed to be about), I've always seen it done internally. On a foundation wall, its more important that it get around the steel than it is to have a few rock pockets here and there. Just smack the forms with a hammer, and that'll take care of most of it. Of course, a lot of foundation crews like the concrete so wet that no vibration is necessary, but as a former QC guy, it makes me cringe.

And I usually say "pour" because that's how I was taught, but when I'm talking to concrete elitists (apparently, there is such a thing), I say "place." An inspector I was talking to once had an old boss that told him to always write "place" in his reports, because if you "pour" it, that means it was too wet.


This would be my advice in this case........


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