| Author | Message |
Ray Darrah 
Posts: 1411
Since: 2/18/2008
|  4/8/2008 8:43:50 AM 
Dialog.. Dialog..
We've had problems with Concrete Mix ratio's since forever, including water to cement ratio.
We've had problems with improper use of add mixes since "bidding".
How the concrete Industry works:
A specifier does not specify the mix. He specifies a strenght/Density and/or a strength the concrete will reach in 30 or 60 or 90 days.
The Concrete Company designs the mix to reach that strength. They may use more fly ash in place of cement to lower costs but if the concrete reaches the strengths specified.......... all is well.
Fly Ash is good to a point. Going over that amount may have adverse effects on the concrete... but nodoby cares except the flooring industry.
Since we are not concrete experts, all we can do is our field tests, document everything we test using photographs and move on to lay the floor.
Impoper use of add-mix to lower costs is a problem we've always had. They've used Sodium Silicates that add ASR issues and plasticizers to increase the flow during pumping only to find out they add to the problem...
With all the concrete being pumped rather than poured, I'm sure there is lots of bad concrete out there.
When pumping, the concrete has to be "plastic" and flowable to flow through... You seldom see anything else used to place concrete these days...
Don't forget:: Lew's article is about "bonding" problems... Heck,, if the finishers would leave a "Broom" finish rather than a "steel Troweled" finish,,,, that would answer the problem. Yes? No? 
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Last Edited 4/8/2008
8:54:54 AM
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Darian Brown
Posts: 712
Since: 2/5/2008
| 4/8/2008 10:06:09 AM
Dialogue yes I think every one needs to go back to your link at the top of the page. Lew is at the cutting edge of our industry he seen it and letting us be aware of it. It has been talked about some what in the White paper.
“In the increasingly complex world of construction – with increasing environmental requirements, technological changes in formulations and advances in measuring and testing concrete – to provide general contractors, owners and architects with optimum substrate conditions/solutions requires greater knowledge and more stringent attention than ever before. Too, new innovative products, installation methods/materials and environmental regulations
have created a more complex environment in which floor covering products are installed.
But it does need more attention and Lew has gave us that. this could cripple a some one business down road.
Indeed very interesting. Lew did not disagreeing with the idea he actually warned us about it so you go a head and lay that floor or you can step up and help your customers with the knowledge you learn got here today.
Ray you may be on to something.
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Roger Gerber
Posts: 327
Since: 3/17/2008
| 4/8/2008 12:08:53 PM
With a broom finish the adhesive manufactures sure would love it. A broom finish takes 50-100% more adhesive, just to fill the texture left by the broom. You would then be forming a mechanical bond as well as a chemical bond.
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Darian Brown
Posts: 712
Since: 2/5/2008
| 4/8/2008 12:43:56 PM
Roger I Hope the installer would know to do floor prep.
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Roger Gerber
Posts: 327
Since: 3/17/2008
| 4/8/2008 1:03:12 PM
So now we have additional cost of floor prep materials and extra labor! Who's paying for this? I can't see the end user/concrete contractor ponying up any extra $.
Oh, that's right tell the installer it is the cost of doing business!
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Darian Brown
Posts: 712
Since: 2/5/2008
| 4/8/2008 2:24:28 PM
Roger what does it cost to replaces a Job?
What dose it cost for shot blasting of job?
What dose it cost to do prep work after shot blasting?
Times are always change just be ready for it.
The only way I can answer the last comment is that a business men charge and a installer loses.
Last Edited 4/8/2008
5:58:10 PM
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Roland Thompson
Posts: 281
Since: 2/27/2008
| 4/8/2008 10:10:31 PM
Darian is right a buiessness man knows what his over head for a job is and then works the figure's to make the profit needed
FD
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Ray Darrah
Posts: 1411
Since: 2/18/2008
| 4/9/2008 7:26:52 PM
There are varying degrees of "broom finish". We're not talking "sidewalk" type broom finish.
Specifiers are writing in the specs "light broom finish" in many instances. A light broom finish is easily skim coated but also ready for Ceramic Tile and Stone installations.
Back to the Fly Ash issue. I've had time to ponder this while on my two day trip. It's been awhile since i worked in the concrete repair industry.
- Steel Troweled Finishes have been a problem.. again,,, since forever.
What happens when over-troweling? The cement fines are "tickled" to the slab surface forming a Matrix wear layer with a density reaching 7,000# compared to the concrete of 3000# to 3500#. This forms a seal on the top of the slab. You've all seen warehouse floors !! They are dark blue and looking close you see spiderweb looking fine/small cracking. That deep blue color is moisture trapped under the matrix wearlayer.........
DO ANY OF YOU INSTALLERS remember trying to glue vinyl to a "converted" warehouse slab surface??? It did not bond well either.
No compare that to a sidewalk that is light colored and turns gray when it rains but soon turns light colored upon drying..... It has a "Heavy Broom" finish and no matrix wearlayer created by Steel Trowels.
Here is a link to the Power trowels that create this problem:
http://www.contractorsdirect.com/Concrete-Tools/Power-Trowels
I do commercial failure analysis for many major vinyl, wood, tile manufacturers and have yet to see this failure. I visit with dozens of Inspectors each month and nobody is talking about this failure. Inspectors are like groups of "old ladies" that sit around a table and tell each other wild stories............ And nobody is talking about this failure... Linda and I visit with inspectors from every state and this is something nobody is seeing. Or not talking about... ANY Body seen or heard of this failure other than reading Lew's article?
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Edited by Admin 4/9/2008
8:16:29 PM
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David Kern
Posts: 518
Since: 2/20/2008
| 4/9/2008 8:34:37 PM
Lew said he is going to have more to say about this 'issue' in his upcoming edition of the Commercial Flooring Report.
I am sure he will shed needed light and perhaps even tell us how the industry is currently being impacted.
One thing is for sure..., he didn't dream this up and certainly wouldn't expose himself in a negative way.
Let's all wait and see.
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Ray Darrah
Posts: 1411
Since: 2/18/2008
| 4/9/2008 9:50:56 PM
David,
It will be interesting to hear more from Lew on this topic.
I would enjoy learning of specific sites and how it was determined the cause of failure was fly ash.
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Ray Darrah
Posts: 1411
Since: 2/18/2008
| 4/10/2008 2:36:07 PM
We've learned that the Fly Ash issues are not current problems, but problems to look forward to.
Everyone may be interested in reading more on Fly Ash and Silica Fume.
Concrete made of Fly Ash over 20% is famous for being Brittle and this may be a bigger problem than Bonding Problems. I hope Lew brings this up in his discussions.
Brittle means cracking and surface cracking off with steel troweling and much more...
Edited by Admin 4/10/2008
3:12:50 PM
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David Kern
Posts: 518
Since: 2/20/2008
| 4/10/2008 2:48:25 PM
This is directly from this catalog:
'Intent: Reduce the use of a very high embodied energy material.
Requirements: Use a waste product, fly ash, to replace Portland cement. Provide cylinder testing demonstrating the effectiveness of the substitution.
Ruling: Fly ash must REPLACE cement content, not just be added as a filler. The Credit Ruling Committee has suggested that a threshold of 40% REPLACEMENT of cement with fly ash.
Regardless of the percent used, fly ash content would count toward MR Credit 4; Recycled Content Materials.'
This is why the issue is so relevant.
Last Edited 4/10/2008
2:52:02 PM
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David Kern
Posts: 518
Since: 2/20/2008
| 4/10/2008 2:56:57 PM
Lew has just released the newsest Commercial Flooring Report addressing this issue further.
ACAA Reply To Fly Ash Issue
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Ray Darrah
Posts: 1411
Since: 2/18/2008
| 4/10/2008 4:26:06 PM
Concrete is specified to meet PSI strengths. In other words: put a sample of the concrete in a vise and squeeze it until it breaks. The PSI (pounds per square inch) strength is measured by the pressure to the sample and at what PSI did the sample crack/break.
Do a search: Concete PSI testing to find many sites explaining this test.
Concrete componants are specified by weight per cubic yard of concrete mix.
In other words. 10 pounds of aggregate x size. 20 pounds of aggregate xx size. 5 pounds of PCA cement. 2 pounds fly ash.
Notice that this is BY Weight, not volumn.
ok... FLy ash weights about 1/4th that of cement....
Quote:
The specific gravity of fly ash is much lower than that of portland cement; therefore,
100# of fly ash has a much greater solid volume than the same weight of portland
cement. Past practice has dictated a cement reduction when water-reducing
admixtures are used; however, in fly ash concrete, the cementitious materials (cement
and fly ash) volume is higher, not lower. This higher quantity of cementitious
materials greatly assists in the finishing process.
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So if the concrete mix is specified by weight how much volumn of Fly Ash is there compared to PCA Cement? with fly ash weighing about 1/4th that of cement, that puts the volumn at twice as much in a 50/50 cement to Fly Ash ratio.
WOW.. is this trouble for strength and structural integrity. Fly ash is well known to result in brittle concrete.
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Ray Darrah
Posts: 1411
Since: 2/18/2008
| 4/10/2008 4:37:13 PM
To continue.
I think Lew needs to stop looking at the left hand (bonding problems) because the right hand is about to knock him out...
I'm thinking the bonding issue can be resolved with broom finishs and a coat of skim coat.
But there is no fixing the Brittle and surface pop off of Fly Ash Concrete. How do we stop the concrete from devoloping more cracks after we install our materials? We cannot stop the additional cracking after installation and concrete continues to dry and shink for years after placement. .. This is why Ceramic and Stone failures for de-bonding and tenting occur 5 to 8 years after installing without movement accomodations.
With Fly Ash Concrete........... I'm thinking the real issue is 1 to 4 years after installation due to the brittle nature of Fly Ash Concrete. I'm interested in seeing PSI testing of 3 and 4 year old Fly Ash Concrete more so than bonding tests.
My suggestion to the Retail and Installation community is:
If this 40% to 50% Fly Ash Concrete Leeds program is passed and becomes a reality::::::::::::::: Get a good attorney to write a Letter of Non-Responsibility for future cracking and surface failures after the day of Installation and state you gaurantee your work, not the FlyAsh Concrete.
This will be a CYA Installation Program.. In fact:::::::::::
Hey Lew... Get together with the resident attorney of this site to design Seminars Throughout the U.S. and Canada to teach the Industry how to protect themselves from Fly Ash Concrete !!
I'm not kidding...
Ray Darrah
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David Kern
Posts: 518
Since: 2/20/2008
| 4/10/2008 6:40:45 PM
Ray,
I passed these last two posts of yours to Lew. He wrote back that he was forwarding them to the concrete and fly ash people he is in discussions with.
He thanked you for the information.
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Ray Darrah
Posts: 1411
Since: 2/18/2008
| 4/10/2008 7:10:17 PM
I hope the little bit of information posted helps put the Flooring Industry in the right direction concerning Fly Ash.
Bottom Line: Ray Darrah, Lew Migliore, and every body else in the flooring industry needs to do their homework on this issue and not allow this "slight of hand" to screw us over.
The entire manufacturing and installation communities need to have tests performed and look at the strengths, surface/bonding issues, cracking, dimensional flexural abilities and all other properties of Fly Ash Concrete compared to Portland Cement Concrete.
Fly Ash Concrete will not be a one issue (bonding) problem.
Here is a site that may be of help:
Lew, do your homework and do not allow this to be a ONE ISSUE discussion. If it is a one issue discussion, it should be about ALL the properties of concrete.
http://www4.eas.asu.edu/concrete/hardened_concrete/index.htm
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Ray Darrah
Posts: 1411
Since: 2/18/2008
| 4/10/2008 7:11:56 PM
another site:
http://www.tfhrc.gov/pavement/pubs/03060/chapt1.htm
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Darian Brown
Posts: 712
Since: 2/5/2008
| 4/10/2008 8:42:50 PM
Ray when did we start give a warranty on concrete cracking? That's like saying Hey, if your building collapses sue me for my carpet glue did not hold it together.
just joking
I do I do agree with your views and this is problem.
Last Edited 4/10/2008
9:54:45 PM
Edited by Admin 4/10/2008
8:49:37 PM
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Ray Darrah
Posts: 1411
Since: 2/18/2008
| 4/11/2008 6:11:17 PM
Darian.. good question.
It's not about warranty.............
it's about BLAME... and we are always blamed for everything...
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