Lbear
Veteran Member
Posts:2740
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| 13 Feb 2012 08:53 PM |
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OZTEC Rebar ShakerIt looks like the better option to pencils. Curious as to how many others out there use it? |
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Chris Johnson
Advanced Member
Posts:878
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| 13 Feb 2012 08:59 PM |
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What do you do if the rebar does not protrude over the top of the wall? What do you do under windows? |
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| Chris Johnson - Pro ICF<br>North of 49 |
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Alton
Veteran Member
Posts:2164
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| 13 Feb 2012 09:03 PM |
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Lbear,
A typical column for a home might have at least four number 5 vertical rebars connected with number 3 stirrups and the column might be at least 12' tall. If so, then will one rebar shaker be enough or is a rebar shaker required to be attached to each vertical rebar during the placement of concrete? Just curious since I have not seen this device used at a trade show like the World of Concrete I just attended in Las Vegas or at any job site. Also, is there any independent, emperical testing to back up this company's claims? |
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Residential Designer &
Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period .
334 826-3979 |
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Lbear
Veteran Member
Posts:2740
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| 14 Feb 2012 03:13 AM |
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Posted By Alton on 13 Feb 2012 09:03 PM
Lbear,
A typical column for a home might have at least four number 5 vertical rebars connected with number 3 stirrups and the column might be at least 12' tall. If so, then will one rebar shaker be enough or is a rebar shaker required to be attached to each vertical rebar during the placement of concrete? Just curious since I have not seen this device used at a trade show like the World of Concrete I just attended in Las Vegas or at any job site. Also, is there any independent, emperical testing to back up this company's claims?
I would assume that a rebar shaker like that becomes just like one large pencil vibrator and any rebar that is tied to it or laying next to it will transmit the vibrations. I can see the rebar shaker working in a lot of applications but the pencil vibrator would still be needed for windows and other areas like lintels. From what it appears, the rebar shaker works best when the rebar is less than 14" OC.ICF MAGAZING ARTICLE:
"The rebar shaker will give you very good results if the rebar is fairly
close together, about 12 or 14 inches,” Oswald says. “If everything is
tied together, it will vibrate the horizontal rebar as well.” At wider
spacings, it needs to be augmented by a pencil vibrator. He notes that
this method produces excellent bonding to the rebar, and is great for
congested areas—like lintels—that would be hard to get a pencil vibrator
into."
ICF MAGAZINE:
" Oztec sponsored testing to compare a rebar shaker
and a pencil vibrator. The test was conducted at the University of
Tennessee by three professional engineers. In each test, the bond
between the grout and the reinforcing bar was verified by performing
pullout tests on the reinforcing bar. The wall was then destructed to
ascertain the completeness of the grout consolidation.
The report concludes, "The
reinforcing bar embedded in grout consolidated with the Oztec Rebar
Shaker met all code development length requirements and was able to
develop the full rupture strength of the #4 bars. No voids were observed
in the grout consolidated with the Oztec/Rhodes Rebar Shaker and good
complete bond was observed with the reinforcing bar. We recommend that
the Oztec Rebar Shaker be fully recognized as an acceptable alternative
to the conventional pencil vibrator."ICF MAG:“We use Oztec's backpack vibrator with the rebar shaker as much as
possible with great results,” says Peterson. This device uses the same
engine as the internal vibrator, but works by attaching to the top of
the rebar, effectively converting the entire steel rod into a vibrator.
It works well for rebar spacings less than 12”. |
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Alton
Veteran Member
Posts:2164
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| 14 Feb 2012 02:25 PM |
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I suppose that the rebar shaker has to be shaking the rebar until the wall or column is full of concrete. Correct?
Multiple shakers might work well enough when the rebar is further apart. I think it would certainly be better than no vibrating at all like I have seen many ICF walls done. |
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Residential Designer &
Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period .
334 826-3979 |
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Lbear
Veteran Member
Posts:2740
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| 14 Feb 2012 02:59 PM |
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Posted By Alton on 14 Feb 2012 02:25 PM
I suppose that the rebar shaker has to be shaking the rebar until the wall or column is full of concrete. Correct?
Multiple shakers might work well enough when the rebar is further apart. I think it would certainly be better than no vibrating at all like I have seen many ICF walls done.
I can't believe that they still do ICF walls without vibrating. The ICF & concrete industry has solidified (no pun intended) that vibrating is mandatory, it is not optional. Do you still see ICF projects today that implement NO vibrating? |
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Alton
Veteran Member
Posts:2164
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| 14 Feb 2012 03:10 PM |
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Yes. Why bother to hire an extra person to run the vibrator as long as the last job did not fall down? When crews show up to place concrete without a vibrator, there is not much chance they will rent one when the concrete truck is already waiting on them. |
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Residential Designer &
Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period .
334 826-3979 |
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TexasICF
Advanced Member
Posts:622
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| 14 Feb 2012 03:34 PM |
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Alton, FYI I've never participated on a single job without a vibrator and sometimes with two or three going on large jobs and I always try to have a backup in case of failure. |
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Alton
Veteran Member
Posts:2164
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| 14 Feb 2012 03:53 PM |
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That is good news. I wish you were located closer to my area. I think more and more concrete contractors will hear about the need to vibrate concrete. First of all, they have to overcome their fear that vibrating will cause the ICF blocks to blow out.
In the last few years, Agilia mix became available for my area. Vibrating is not needed when this mix is used with the right application. So far, the higher cost for the mix slows it acceptance.
Some of us have known for years that the typical ready-mix concrete needs to be vibrated when it is placed in a narrow or congested area. When I helped build an addition to a TVA power plant from 1966 to 1968, vibrators were used on walls and floors. My older brother and I both worked there. He spent many a day vibrating concrete at the Paradise Steam Plant in KY. |
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Residential Designer &
Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period .
334 826-3979 |
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Chris Johnson
Advanced Member
Posts:878
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| 14 Feb 2012 08:10 PM |
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The whole purpose of Agilia is it does not increase your costs, the additional funds for the product is offset by labor savings. Unfortunately most people don't see it that way, they only look at numbers and not take into account all factors. |
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| Chris Johnson - Pro ICF<br>North of 49 |
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jeepster
Basic Member
Posts:153
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| 14 Feb 2012 10:39 PM |
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I've never used the Oztek. I couldn't justify the cost. But, since I have a metal lathe, I decided to make my own. It's basically an adapter threaded onto an angle grinder. I simply made an offset bushing and an adapter that fits over the rebar. Since my angle grinder spins a 12,000 rpm or so, it matches the speed of most vibrators. The tool worked remarkably well. When we were pouring up past the window openings, the pencil vibrator was struggling to move the concrete into the forms under the window openings. I put the "rebar shaker" on the verticals and concrete just flowed in nice-n-smooth.
That was the first lift -- 3-4 feet. The next lift the shaker didn't do so well. As a matter of fact, I don't think it "consolidated" the concrete hardly at all. I think it prevented voids, but I'm sure it didn't do it's job with air bubbles and such. We pretty much used the pencil vibrator from that point on. I'm sure it's because the first lift sounded off and that prevented the rebar from giggling as much. |
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robinnc
Advanced Member
Posts:586
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| 14 Feb 2012 11:25 PM |
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What is the dif in price per cubic yard? I've never heard of this concrete before.
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Chris Johnson
Advanced Member
Posts:878
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| 14 Feb 2012 11:59 PM |
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Robin, I think most US ready mix companies call it SCC or Self Consolidating Concrete, the concrete is literally liquid when you pour it, I mean if you try and do a slump test it's impossible, picture pouring water on the floor, same idea. It's not for the light at heart, if you have any questionable sections in the wall or weak spots, this mix will let you know really quick.
Cost is about 20% more per yard in Canada, not sure in your area |
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| Chris Johnson - Pro ICF<br>North of 49 |
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smartwall
Veteran Member
Posts:1209
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| 15 Feb 2012 09:56 AM |
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Try Fritz Pak. the 5 or 7 will give you great results with little or no vibrating. I've posted on here several times about vibrating, like a pencil vibrator is worthless, read the Oztek specs on vibrators. I'm a bit anal about making sure the walls are fully consolidated so I found the issue of a proper vibator to be an important one. Recently I've been using Frtiz pak products along with increasing the fly ash to 35% versus the standard 20%. As my dear departed friend used to say," slicker than snot on a bedpost". This is one rearon I like to use 4" forms when possible along with Helix fiber. |
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cmkavala
Veteran Member
Posts:4327
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| 15 Feb 2012 11:02 AM |
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I have used a "Super Plasticizer" in the mix that looks like grey water out of the pump hose |
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| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
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smartwall
Veteran Member
Posts:1209
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| 16 Feb 2012 07:47 AM |
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You never want to start with a slump over 3 when you start. I know Fritz has 6 different levels of water reducers. |
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jacktca
Basic Member
Posts:180
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| 16 Feb 2012 04:14 PM |
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Says this thing is for rebar 3/4" thick or more. That's awfully thick rebar. My plans specify #4 but I'm going to use #5. That's still way too thin for this rebar shaker. |
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robinnc
Advanced Member
Posts:586
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| 16 Feb 2012 10:12 PM |
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Thanks Cris for the info. Sounds alot like gypcreet when doing alot of tiling.
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Lbear
Veteran Member
Posts:2740
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| 17 Feb 2012 10:15 AM |
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Posted By jacktca on 16 Feb 2012 04:14 PM
Says this thing is for rebar 3/4" thick or more. That's awfully thick rebar. My plans specify #4 but I'm going to use #5. That's still way too thin for this rebar shaker.
They make a smaller rebar shaker, the one you were looking at was the large heavy duty one. Here is the smaller one: Oztec Standard Rebar Shaker |
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woulfcc
Basic Member
Posts:147
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| 22 Feb 2012 12:04 AM |
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I do not like it , I will not use it on an ICF. |
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| Changing How the World BUILDS!<br>Green , Done , Easy<br>Woulf c.c. of Wisconsin |
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