as you will hopefully find out I'm trying to ask great questions that will help not just me but others

lets talk about concrete admixtures so we can ALL learn about this topic.
i would like that if someone would like to know about concrete admixtures they can come to this

please answer what you can on the different concrete admixtures that you know, and please let us not get stuck on just one {say like plasticizer} lets talk about all of them

i would like to know what the admixture is and what does it do
also any good and bad of that admixture
and also please answer some questions that i have with it

i am using the terms that my resurch has been with this forum

#1   Plasticizer
            i know that some of you do not like plasticizer, but do any of you use it

#2    mid and high range water reducers
            what is the difference between a mid range and a high range, is the high range a plasticizer

#3   SCC  self consolidating concrete   
            how does this differ than the plasticizer

#4   Viscosity Modifiers

#5   Fly Ash
            what does adding fly ash to the mix do, and what percentage do you use

#6   Higher psi Mix
            what does useing a higher psi mix do, say a 4,000psi mix {or higher}over a 3,000psi mix

#7   Higher Slump
            what happens when i incress my slump

#8    What admixtures do YOU use

sounds to me sombody needs help with their homework...

jk

You ask some great questions there, RD. I like the link Bruce gave, but it doesn't say much about fly ash, my additive of interest. I'm just a new owner/builder but I've read that you can replace up to 25% or so of your Portlant cement with fly ash. This not only reduces the Portland (the only 'bad' ingredient in concrete, due to its intensive production process); it also replaces it with something that otherwise goes into landfill, since fly ash is a waste product of coal power plants. And the folks who sell fly ash tell you it also improves the concrete in several ways (detailed at http://www.flyash.com/performance.asp). What they don't say is that some people are worried that the mercury in fly ash isn't completely locked up within the dried concrete, making a possible health risk if the concrete is exposed to the living area of the house. That's my worry, since I'm using concrete floors and walls for thermal mass, so I'm staying away from it. Does anyone else have other knowledge about fly ash? ...Terry

In my area almost all concrete carries 20% fly ash.

For 98% of all residential appliations, the only admix you need is air entrainment and a basic water reducer. The air is for exterior flatwork, to resist freeze/thaw damage. In areas where freezing can be an issue, all exterior flatwork should contain air. With today's admixtures, Slump is a definition of workabilty, not concrete quality, unless you increase it with water. If you increase slump with water, you waste cement by increasing the water/cement ratio. Higher w/c ratio concrete comprimises strength and durability, shrinkage increases (which leads to increased cracking). Excess water can also lead to dusting, crazing, discoloration, delamination, etc! Most residential flatwork should be placed at about a 5" slump. If you want higher slump, do NOT add water. Order (and pay for) a mid-range water reducer. This will give you a 6 to 7 inch slump for ease of workabilty, but keep the water/cement ratio the same. Because of the above reasons, water can be the most expensive admixture you can get.
I recommend fibers for exterior flatwork as well. Good value for the money. From what I have seen, fibers are much, much more effective than wire mesh. Fiber technology has improved significantly and they are very impressive. We carry several different types for different applications.
For garage floors or interior slabs, you can order a .42 w/c ratio mix with fibers and a shrinkage reducing admixture. Be sure your contractor does not add water. We have supplied this type of mix and our contractors produce beautiful 3 stall garages with no joints or cracks. To do this, you have to follow proper ACI practices regarding sub-grade, curing, etc., but it can be done. For most residential concrete, a 3,000 psi mix is fine, as long as it isn't placed too wet (remember that w/c thing...). If you are looking at a heavy motorhome or periodically have large loads, go thicker with a 4,000, and be sure to follow ACI jointing recommendations. All of our residential mixes contain about 15 to 18% fly ash. The right type of ash is a very good additive that increases density, durability, etc. We have used it for over 30 years, but don't get crazy with over 25% ash. This can lead to set time issues, etc. I would not worry about the mercury in fly ash. Fly ash reacts with the calcium hydroxide in cement and cannot leach out of concrete...
Super plasticizers and SCC are great technologies and we use them often, but they are overkill for most residential applications and there has to be an engineering, schedule, strength or other reason to use them to justify the cost. We can pretty much do anything you want with concrete, but you have to be willing to pay for it...
For success with concrete, follow ACI standards. Proper sub-grade prep, good mixes placed at the right slump, proper finishing, jointing, protection and curing eliminate 98% of problems. Talk with your local concrete supplier's sales staff and explain exactly what you are wanting to do. They will be happy to help and can recommend contractors that produce quality results.

Concrete Producer,

Very good, quality information! It would be great if we had more of this type of input on greenbuildingtalk.com vs. the confrontational and chest thumping type that we continue to see here. The personal attacks on this site are enough to make me want to never come back until people like you remind me of what the forum is or should be all about.

Thank you, again!

YES! Concrete Producer, you do good posts. Thanks, FM

Concrete Producer hit most of it dead on.
SCC isn't necessary for ICFs. As a matter of fact, it can be a detriment. It usually has smaller aggregate and a whole bunch of HRWR (Sorry, I don't like the term Super-P). This of course makes it more fluid. Meaning it exerts a higher load on the forms.
I'm a BIG believer in flyash. It amazes me that some engineers still don't even allow it. I'd add 10% to 15% just for starters. At makes for better consolidated, and a more dense concrete. Meaning more water-tight and harder. One thing unknown by many: in the desert southwest, as well as some places in the east, the have an aggregate problem that, when used in concrete has ASR: alkali-silica reactivity. Simply put, the cement causes the aggregate to swell in the presence of water, and can actually crumble the concrete apart. Using 20% to 25% flyash will usually mitigate the problem.
Fibers: I like them too. Don't be misled as many are about WWF being no good, though. If it's placed in the center, and sized right (minimum 6-6/ 10-10 using the OLD designation) it's fine. How many of us have seen it placed to where it REMAINS in the center. Can't misplace fibers.
I've never heard the term viscosity modifier, but I expect it's the same as water reducers.
Slump is simply a measurement of "flowability" (hence, workability) and is affected by water reducers, and of course, water.

I appreciate your positive feedback. While I am on the soapbox, I want to address Terry's comment about Cement being the only "Bad" ingredient in Concrete. I see that opinion many times, especially from the green building crowd. They read this somewhere and regurgitate it on all greenbuild sites ad nauseum without really thinking about it. Without the cement in concrete, you have wet rock and sand...  WooHoo!  Thus cement is the CRITICAL ingredient in concrete, not the bad one. People need to get beyond the cement and think about what the product it makes does for them. Cement typically comprises only 10 to 12 percent of the entire mix. When cement is mixed with water, sand and gravel, the result produced by the reaction (cement hydration) is concrete–the familiar rock-hard substance that is the foundation of the built environment. Think about life without concrete...

When cement is made from limestone, some of the original carbon trapped in the limestone is released by calcination. To change the limestone chemically to make cement clinker, the limestone is crushed and heated in the kiln to 2,700 degrees F. More carbon is released from the coal or other fuels used to heat the kiln. The bottom line is about 1,800 lbs of carbon is released per ton of cement produced. Today’s U.S. cement industry accounts for less than 1.5 % of the nation’s CO2 emissions (compare this to electric generation plants for heating and cooling which contribute 33 % of the US CO2).

Now let us get back to building a house. A typical ICF home would require an addtional 80 cubic yards of concrete. This would require about 20 tons of cement, the CO2 released in making that cement is negligible compared to the increased efficiency over the wood home the ICF home replaces.  Because of its reduced energy requirements, the breakeven point where your ICF home generates less CO2 is approximately 10 years. In 50 years, your ICF home saves 92 tons of CO2 emissions compared to your neighbor's wood house. Bear in mind that this ICF house is one that will withstand hurricanes, fires, earthquakes, tornadoes, etc. and has a very low propensity for rot and mold. In order for something to have true sustainability, it first requires durability. Concrete does not take a back seat in durability.

Concrete pavements are another great illustration of this. The National Research Council of Canada studied fuel efficiencies of commercial trucks on both asphalt and concrete pavements. The study demonstrated significant fuel savings for semitractor trailers on concrete pavements. Because concrete is a rigid pavement and offers less rolling resistance, trucks traveling on concrete roadways use up to 6.9% less fuel. Our National Highway System presently consists of approximately 160,000 lineal miles of pavement, 59% of which has an asphalt surface. If all these roads were concrete surfaces, truckers would save over 2.1 Billion gallons of fuel per year, eliminating over15 million tons of CO2 emissions annually. This would also decrease the cost of transporting goods, benefiting our economy. Concrete pavements also are reflective, safer at night, produce less heat island effect, and reduce stopping distances.
I have been in the concrete industry for over 30 years and am proud to produce a product that helps people and the environment. To me, ICF is like an Oreo. The "good stuff" is in the middle!
I hope this information helps you convince more people to go with ICF.

YEA! This thread is probably the best I have ever read!

ICF's are just another way to "form" a reinforced concrete structure.

Has anyone ever seen a sane man walk on top of a ICF wall? Not until it has been filled with concrete!

Well, once I did, but that's a different type of ICF. Salesman stated "that they not only stood by their ICF's, they stood on top of them"...he was a big man, even jumped up an down. But it was still an ICF and it was jst another way to create a reinforced concrete structure.

I'd like to thank Concrete Producer for his information and the others for their feedback. I can understand the comment by the 1st as to " doing your homework" and I find that this site is my homework.
Understand that my background is carpentry/construction- I like wood. I was never very familiar with concrete and now that I am into ICF's I am trying to educate myself on concrete but I am finding it difficult to find good current info. Some of the Q's by Rd I want to know also...thanks RD.
We are all knowledgeable in our own certain fields and we all went down the road asking questions to get there. I'm finding myself on another path and in order to be good at what I do I too am on another learning curve and right now its concrete and ICF's.
So where is all this information hiding where I can do my homework. Do I have to join the Concrete Assoc. and pay alot for all the separate publications because thats what my current homework has shown me.
Again Thanks for your feedback. Randy

Randy, I do my best wood work with a chain saw... so I am not one to talk about carpentry skills, but what we have found is that carpenters make great ICF installers. They understand plumb, square and level and once they get into ICF they find the dreaded learning curve for ICF is a lot easier than it was when they originally learned framing. Once they realize that you don't need insulation, vapor barriers, etc. they really like it. Most I have dealt with build about three ICF projects and become real ICF proponents, preferring it for envelope construction.

Good ICF manufacturers offer training classes, as well as dvds, etc. to help you out with the ICF side of things. Regarding concrete, see if someone at your local concrete company has taken the National Ready Mix Concrete Association's Certified Concrete Sales Professional Class. That person, or someone in Quality Control, should be able to walk you through their lab, show you their plant facility and give you an overview of the various mixes they offer and the materials they have and why (or why not) you should use what material or admix when. Concrete is made from natural materials and thus, like wood, it has natural variations.  That being the case, we might be able to supply a mix out of one plant that has certain characteristics, but from another plant, we have different materials, and thus things are going to be a little different. 

There is also a lot of good concrete information on the NRMCA website, which is www.nrmca.org The Concrete In Practice sheets are very helpful for trouble shooting and avoiding problems. You can find them by doing a search of the site. There is currently also a link on the right hand side of the site. 
When we started selling ICF in 1996, we decided to solve this issue by employing a full time ICF technical advisor, who helps train indivdual contractors on how to do ICF, and then he helps them with the first few pours. This service is free for contractors and DIY customers are happy to pay for this experienced assistance.

Related to the original post but maybe more theoretical than practical, does anyone have thoughts on crumb rubber / recycled tire rubber as an additive in a portland cement concrete (PCC) ? It seems like it would be a good use of recycled material, and might have other benefits like increased sound deadening?

-dialectric

Dialectric, you are correct in the sound attenuation benefits and crumb rubber is used in asphalt for that reason. Rubber will compress however, so it is detrimental to concrete's main attribute, compressive strength. Asphalt is a flexible pavement, so the crumb rubber works. Concrete is a rigid pavement. My previous post on this thread illustrates the fuel savings with rigid pavements.

Our industry does, however, use waste tires as fuel in the cement kiln. A normal tire fire burns slowly at 500 degrees, creating toxic black smoke. When tires are used in the cement kiln, at 2,700 degrees, they are pretty much vaporized, so there is no smoke or pollutants released. Cement plants can use tires for up to 10% of their fuel requirements. Even the steel cords get melted into the clinker. We also use windpower; we have installed 8 large windmills to help with our power needs at our cement plant in Mojave, CA. Both tire derived fuel and windpower save on coal, which is the most common fuel for the cement kiln.  Cement plants that burn tires have to get permits to do so and the emissions are closely monitored by State and Federal agencies.

The most common recycled products in concrete are fly ash and slag, depending on what part of the country you are in. A mix still needs cement, but 20% replacement with either one of those makes good sense and makes a denser concrete, usually with slightly higher compressive strength and increased durability.

Other additives to consider are:

Glass or other fibers
Magnesium Oxide (adjusts shrinkage and can prevent cracks)
Acrylic polymers / bonding agents

#1 Plasticizer
i know that some of you do not like plasticizer, but do any of you use it
- Plasticizer is for use when you have a mix that requires 20% or more water reduction. Usually 5000 PSI or higher.

#2 mid and high range water reducers
what is the difference between a mid range and a high range, is the high range a plasticizer
- Midrange waterreducer is for 5-8% water reduction, HRWR is for 20% and higher

#3 SCC self consolidating concrete
how does this differ than the plasticizer
- Polcarboxylate admixtyres are used to create flow.

#4 Viscosity Modifiers
- Only needed if you have gap graded aggregates

#5 Fly Ash
what does adding fly ash to the mix do, and what percentage do you use
- Adding flyash reduces permiability, reduces ASR, Reduces mix cost and is better to finish.

#6 Higher psi Mix
what does useing a higher psi mix do, say a 4,000psi mix {or higher}over a 3,000psi mix
- Depends on the job requiremnts

#7 Higher Slump
what happens when i incress my slump
- If you use water to increase slump the concrete will lose strength and reduce durability. If you use a water reducer it will not harm the concrete.

#8 What admixtures do YOU use

mugzy;

I use #1 & 6

I have used #5 and #6.