Guys,

You may have seen this already....but here is a nice article regarding consolidation techniques.....

LINK

Leonard

Great article! Thanks for posting that!

Thanks Leonard!
And just in time for me to sleep peacefully again, all that "gravelling" fiction in other posts has had me close to a nervous breakdown....sorry, just a little Christmas sarcasm.

Merry Christamas all, sleep well.

Kevin

Kevin:

Before closing your mind and your eyes, please just consider the possibility.  We all install differently, and place differenty, and with outside factors, there are concerns.  I have clearly stated that in most cases, its not a problem, however does happen rather often which is a concern.

This not an argument or sarcasm.  Your choice if you want to ignore it, however please dont mislead people into thinking that this report reflects all concrete placed by all people, in all areas of the country.

Also please look closely at the report, there is a lot of information in there, for those who wish to see, with an open mind.  I know you will likely have some form of reply, I hope that we can maintain a professionalism on this board and not be argumentative.

Lastly Happy holidays.

Mark Ross

Dear Mark:
Good morning: (that will be the professional and non argumentative portion of this post)

"how often does happen rather often" is a lie. Again, prove your theory. You need to stop your incessant unbacked, unproven raving about gravelling.
"your choice if you want to ignore it" is inflammatory, I have asked multiple times for proof and documentation, I have pleaded with you to teach me/us. But I am not a sheep.
"however don't mislead people into thinking this report reflects all concrete placed by all people, in all areas of the country" I have not misled anyone, nor quantified the methods or results of the report.

The pictures speak for themselves, when improper mixes and methods are mixed in an imperfect world, imperfect finished products results. So stick with someone who is experienced.

People, be not afraid of cars, but rather the drunks behind the wheel of them....

Again, good morning
Kevin

It is my understanding that RD134 is the result of a study conducted by the Portland Cement Association addressing concrete consolidation and the potential for voids in icf's.  Wall sections were erected according to manufactures specifications, proper concrete mix was placed and vibrated using the manufactures recommended techniques for concrete consolidation.  The foam was then stripped away and the results of the consolidation methods were clearly seen and that is what RD134 reflects.

External vibration provided little assistance in improving consolidation.  Internal vibration was found to provide adequate consolidation.  Pictures do speak for themselves and as the saying goes "a picture is worth a thousand words".  Internal vibration is key to proper concrete consolidation and that is what I take away from this report.  I will not build with or represent a block than cannot handle internal vibration and RD134 is one of the tools I use to explain why.

There are still icf builders out there who refuse to vibrate at all because they either do not believe in its effectiveness, they are cutting corners or they are building with a block that cannot handle internal vibration.  Experience is the best teacher and unless or until a builder experiences voids in a wall the lesson of the importance of concrete consolidation will not be learned.

I recommend and use internal vibration and did so prior to reading RD134.  After reading RD134 all I could  say was "there you go".  If you think about it, styrofoam is used to absorb sound and vibration in a submarine which is another reason to point to why external vibration is futile.  The foam absorbs the vibration before it can get to the concrete behind it.

icfgal

Wow, this thread sure generated some response. I thought it is "common knowledge" that internal consolidation is the only way to go, short of perhaps some super liquid SCC with slump of 20+. This article nicely and very professionally put forth the various consolidation techniques and their results. I don't think you could ask for more.

If there is one of those "must read" papers for ICF I believe it is one of them.

Thanks for the replies and I am glad the link is appreciated.

Leonard

We have talk about this a year ago and the answer is still the same, Internal VIBRATION!
I have looked out of the box for a long time but this on is just the way that works for me.( I'm still looking)
Until I see something that dose not have graveling, voids, or cost more I will stay with my vibrator and walk (RUN) away from those that don't use one.
You do what ever you wish, Just think about it all other concrete is internally vibrated in to its forms (why is an ICF different?)
Can one of you prove to me with this level of documentation that some other way works?
I am looking to shelf my vibrator also. (it is work to use it, one of the hardest jobs during the pour) dragging a power cord up on a cat walk droping it in and pulling it out over and over again. The block looks good before I vibrate and some times vibration will change it,(blow outs, bulges, Coming back to fill in after it drops the level Of concrete down) all of this is work.
All of this is good concrete.
Show me That I don't need to work this hard. I'm all ears.
Scott

Might as well join the fray again.  I believe everyone here is a forward thinking person or they wouldn't be building with icf's. 
I have seen the results put forth in RD134 long before it was printed.  I am sure some people must be having results without internal vibration.  I have not had the opportunity to see for myself, consistently good consolidation without the use of an internal vibrator.  RD134 seems to back up my thoughts.  Much like the price of concrete reported on another thread here concrete makeup is inconsistent throughout the country.  If we could all get a product delivered at a fair price that would "self consolidate" without the possibility of voids I am sure that the entire bunch of us would jump on it like the proverbial "duck on a junebug".  Till then I will continue to internally vibrate.  
I have had the opportunity to see pictures of "graveling"  at its worst.  You could dig a hole through the bottom of a concrete wall with your fingers. Does this happen often? I don't think so, but it does happen!  The internal vibrator goes a long ways towards prevention of voids, honeycombs and graveling in concrete poured in icf walls.   
We sure have had a lot of fun with this thread this year.

May we all stay well and prosper in the new year to follow!

Happy New Year,

I guess people tend to view RD134 based on their prior convictions. I took away from the article that you can forget vibrating if you have the right mix. Sure, it costs more and you have to trust your supplier (or test, not that it does much good to know 28 days later that you didn't get what you wanted). It would seem that a calculation of admixture cost vs. tool rental/labor would be simple. But I'm not sure if you would be comparing apples to oranges because of the difficulty of actually vibrating the entire wall.

The article implies that you would have to drop the vibrator down about every four inches for proper consolidation of a low/medium slump mix. For a little house (25'x25' with 8' walls consisting of two 4' lifts), that would be plunging the vibrator down 4 feet approximately 1,200 times during the pour. On a McMansion, you're looking at 3,000-4,000 plunges. Realistically, that isn't going to happen, but that's what you would need to get the same result as the admixture. Vibrating is the old-fashioned buget-based attempt to approximate the consolidation obtained with new-fangled admixtures. Sure, it works okay and it's likely good enough for most projects. But I certainly didn't come away with the notion that vibration was the superior method.

One of the questions that the study raises for me is the issue of computing pressure at the base of a form. The ACI standard that treats concrete as water is clearly suspect. Unlike water, the rougher the internal surface of the form is, the less pressure at the bottom. What would be interesting is to see how much the pressures differ for the waffle and screen-grid forms, which would have internal ledges and passage ways to further reduce pressure. Whatever the pressure, the form still has to resist it to stop blowouts, but it might be interesting to see whether a simple change in the internal surface texture could reduce the overall pressure at the foot of the form.

Mark Fleming

Mark,

You are correct about the SCCs (Self Consolidating Concrete). The study states they show favorable results. But the study also states in areas of a lot of rebar they should also be mechanically vibrated even with the SCCs. The issue of SCCs for me is not the price but the consistency and the knowledge from the concrete producers to give me what I ask for. I can't count the number of times I have heard from a dispatcher "well I thought...". So, when or if I order a mix design outside of the dispatcher or sales persons understanding, I usually go down to the plant and give them the design and sign a contract to ensure I get what I ask for. The other issue with SCCs is the ACI's acceptance of them. I haven't really kept up with the true SCCs, but I thought the ACI had not made a determination of their acceptance yet. Maybe I am wrong, like I said I haven't paid attention to them for awhile.

Your issue about having to stick your stinger in the wall so much can be solved with a few tweaks. First of all they were using a 1.2 hp 3/4" stinger that in my opinion has a hard time shaking the dew of a Lilly let alone consolidate concrete. We use a 3 hp 1 1/2" to 2" vibrator in our walls as well a using a high performance concrete mix with plasticizer, h2o reducer, slag or fly ash, and a viscosity modifier at a 6" to 7" slump. The concrete flows really well and with the higher slump and larger vibrator increases the zone of influence of the vibrator dramatically. I have always encouraged people to take one of the ACI concrete consolidation classes if you can because I think they are well worth it.

ICF Contractor

One of the comparisons I would have liked to have seen in the article is the effect of simply "rodding" the concrete.  Pounding on the outside seem to be a joke.  How about rodding from above with a piece of rebar?  I can't imagine that you could end up with the giant voids that resulted from "vibrating the outside of the form" type of consolidation.

I was helping of a pour using what was supposed to be self-consolidating low-slump concrete on an 8 foot wall.  There were some places where we dropped verticals down after the wall was poured.  I remember feeling that the rebar wasn't placed quite right so I pulled it up, monkeyed with it as it went down, and the level of the concrete dropped two inches in the form around the rebar.  In another spot, we found that the rebar had been left proud of the form and we smacked the rebar a few times with a framing hammer.  The same thing happened.  The forms rep was on site and he said don't play with the verticals when dropping them.  What?  It had to mean that I had poked through a void and that smaking the rebar brought up some air.  Not my house, not my project, not my problem.  Also not a rep I'd take advice from.

Mark Fleming

Mark,

I have done a few non-scientific experiments of my own usually to show a contractor the value of vibration. When pouring some 32" stem walls at a 6" slump I have had conrtactors, who are use to pouring conventional panels, go ahead and consolidate using what ever method they usually employ. Most tap on the sides, I tell them lets do more. So we will use a sawz all, a thumper, a block of wood with a hammer, and good old fashoned rodding. Now mind you this is done to the whole wall all of these methods. The usual response I get when I ask them if they feel it is sufficiently consolidated is usually a resounding yes. They will say that they never would normally go to that effort to consolidate a wall. So then I pull out the vibrator and consolidate the wall and have had concrete levels drop from 1/2" to 2" in a 32" wall. That usually make believes out of them.

Now if the ASTM comes up with a testing method for SCCs I think I would definately experiment more with them. I have several buildings I need to build at the yard.

ICF Contractor

Most ICF companys have a amount per form of how much con is needed in the walls to fill the form.

The main two methods SCC or internal vibration should result in the total consumption of the concrete ordered. Some spillage will occur but that is ok. There will be some left in the pump at the end.

We calculate this amount on every job reducing the amount for doors and windows. When you have completed the project you should have 1yd left in the pump and may need some of that to finish off a small area at the top of the wall. We have found this to be very consistant and a good indicator of consolidation.

Bill:

I cannot agree with you more. I have been so dissapointed with the number of installers who send back several yards of concrete, thinking they overordered, without realizing the true implications of what has occured.

Mark Ross