Cement Replacement or Additive

Plenty of info on fly ash and its use as a cement filler.

http://en.wikipedia.org/wiki/Fly_ash

http://www.flyashindia.com/fly.php

www.scientificbulletin.upb.ro/rev_docs/arhiva/full8347.pdf

Try googling "fly ash cement filler" (or similar) also for plenty more. There should be some good handbooks and application notes available for download that cover various cement filler mixes and their properties.

There are many possibilities. Contact me at tesla-was-right@hotmail.com and I can inform you of a few--some which use fly ash and others which can but do not have to

Ceramic Cement Research Institute

You could employ a stone mason. I often do quick retaining walls from rock and mortar where the initial wall was going to be concrete but the customer baulked at the price.

So, the materials for the retaining wall + my time ends up being cheaper than forming a concrete wall and pouring it. The rock walls are generally a lot thicker at the bottom too than the concrete ones so less likely to bowl over with hydraulic pressure behind the wall and the stone mason can do little inside curves if you like to move the center of gravity even further back. Lots of retaining walls use busted up old concrete floors or pavement as their backing and just the pretty stones for the front of the wall so they are good recycling too!

Also If you do (after all that!) a concrete wall and you get the most suitable sized aggregate (largest with the right mix of finer particles) for the job, you can still have a very strong wall and save quite a lot of cement. On Vancouver island, sand consistancy is horrible. Some coarse sand is great while some is almost like gravel! If standards are uninforced in your area too, shop around for aggregate and that will save a lot of cement.

You can mix 8 parts of clay type subsoil to 1 part Portland cement, adding only enough water to form a dense mud-ball. Use a 'rammed earth' technique for footings, walls, and floors. It takes a long time to set, but is both durable and somewhat flexible in the event of frost loading. You cannot drive a common nail into it after a year, but you may build on it after a month.

You know I was actually hoping to find some good intelligent responses to this question and can't believe how weak these responses have been. Why do you people even respond when you don't have anything useful to add to the question?

First of all in regards to the question, Fly Ash is what is left over from the burning of coal in power plants. So if you wanted to make it that is the first hint. It probably wouldn't be worth the effort to make.

I've spent alot of time on this topic recently since I am building my home out of a ICF block and need to fill my walls with a 2500psi grout. Fly Ash was the recommended choice in one of the mix recipes I found but it is not like you can run down to the local home improvement store and purchase. The only places I found were from the concrete companies themselves at which point I found it easier and actually slightly cheaper to just order from them as to wasting the time and effort to make it myself.

In my research though I have also found that there are better choices. One of the things I am gearing up for is making my own stone veneer that would be modeled after the local rocks in the area and not the generic offerings from the suppliers. I am presently waiting on a response as to where I can purchase what a stone veneer manufacturer recommends which is a Type N natural pozzolan instead of Fly Ash (Type F pozzolan). Supposedly the Type N is a much better filler than the Type F. Sorry I couldn't have been more help but at least I did try to address your question instead of telling you to google or try a different method responses.

Hi Beraqpront,

Your desire is valuable but the performance of your new and modified cement could be a disaster. However, in the past I already modified cement compositions with up to 4% of Fly Ash without deteriorating the performance.

All modification or replacement of cement, create some problems, depending of the materials used and the quantity of them. Important is to maintain the cement/water ratio the same. When some changes occur, problems start.

Cutting costs is dangerous on the performance of the concrete, Gil.

GA to Sonave Sunsets!

I have to agree with him on this one. Yes, you can use fly ash to sub-plant the use of Portland Cement in order to reduce costs, but up to a point! I've specified concrete mixtures where fly ash replaced 17% of the cement on a weight basis, but yet again, the starting basis for the amount of cement in the mixture was fairly high.

Why on Earth would you want to make fly ash when it can be bought directly from a local concrete company, assuming of course they'll sell it to you at all? Do you own a coal fired plant????

Also, cutting back on the amount of Portland cement in your concrete mixture just for the sake of cutting costs is like cutting your own throat....after all, the compressive strength in concrete is derived primarily from the cement....the Ancient Romans knew this, and we can to the day still see marvelous works of theirs made with concrete some 2,000 + years later! And, they also knew not to mess around with the ingredients too much to the point where the concrete strength was weakened....like watering it down too much (water-to-cement ratio) or reducing the overall mass percentage of the cement in the concrete mixture.

May I suggest that you attend a concrete material lab course at your local community college that offers Civil Engineering Technology (AAS Degree). You may actually learn something invaluable by taking such a course....knowledge!

A great sunny day!

interesting to note that the Roman concrete was made with pozzlanic fly ash (naturally occuring from pozzlana)

Portland cement was not invented until the 1800's

10,000 psi concrete can be made from reactive or non-reactive fly ash if one changes the binder. 80% fly ash and 20% binder is sufficient and it is full strength in 24 hours at normal ambient temperatures (no special curing techniques required)

You may use; as desired, on an equal weight replacement basis, fly ash, silica fume, metakaolin, other pozzolans, and slag materials as a cement replacement in all concrete. However there are limitations based on the application.

The best source of information for concrete mix design is the American Concrete Institute (ACI). There you can pick up DESIGN AND CONTROL OF CONCRETE MIXTURES on CD for about $80.

Designs should be tested for the desired compressive strength and always produced in the proportions from the tested design with water cement ration being the most critical.