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  #31  
Old 10-11-2012, 02:29 AM
brickie in oz's Avatar
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Default Re: foam concrete

Water and detergent? How is that remotely comparable to fine concrete and detergent?

Try it with fine concrete and detergent, the bubbles may last longer.
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  #32  
Old 10-11-2012, 03:39 AM
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Default Re: foam concrete

No, the foam is generated first, then mixed into the cement slurry. I used normal detergent as a test to see if my homemade foam generator worked ok.
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  #33  
Old 10-11-2012, 04:24 AM
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Join Date: May 2011
Location: South Australia
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Default Re: foam concrete

Quote:
Originally Posted by waikato pizza View Post
Hi all - I'm a newbie so hopefully will not be re running old info

I have stumbled across another version of the lightweight concrete. Cellcrete (apologies if this is a brand name only) is a concrete sheet like a giant honeycombe bar of aerated concrete. I have been told that it is made by mixing alumium swarf into the concrete. The whole thing is then heated to a point where the aluminium burns and vaporises leaving gas bubbles behind it. Hence it is already hardened and can be cut using a hand saw.

I will be giving this a try and will let everyone know how I get on - watch for the saga - I aim to eat pizza by christmas!!
I would suggest it is probably like every other form of aerated concrete made with aluminium powder - the aluminium reacts with the lime in the concrete, which generates hydrogen, which foams the concrete.

Edit - I just goggled cellcrete - its done with a foaming agent water and compressed air, just like Dave is trying to do.

Last edited by wotavidone; 10-11-2012 at 04:42 AM.
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  #34  
Old 10-11-2012, 04:36 AM
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Location: South Australia
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Default Re: foam concrete

Dave just looking at your foam generator, I wonder if you can find a sintered frit to put on the end of your air injector pipe. This might help with making smaller bubbles. Take a close look at the small disposable fuel filters they sell for motor bikes, some of them have sintered bronze inserts that you might be able to utilise.
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  #35  
Old 10-11-2012, 04:44 AM
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Default Re: foam concrete

Yes, you may be right. I did flatten the end of the pipe so there would be a finer jet. Perhaps one of those aerators that fish tanks use would work too. I shall see how the foamer performs when I get it.
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  #36  
Old 10-11-2012, 06:03 AM
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Default Re: foam concrete

In molecular gastronomy they use lecithin to make a foam ,its still cheap and more stable than detergent.
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  #37  
Old 10-11-2012, 03:02 PM
Peasant
 
Join Date: Oct 2012
Location: Waikato New Zealand
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Default Re: foam concrete

It sounded amazing, but as you know if it is to good to be true it often is, thanks for the street.have you used the concrete sheets like this at all, I guess they are in Oz ad
d well as nz
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  #38  
Old 10-12-2012, 11:17 PM
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Default Re: foam concrete

Made some improvement today. I fitted a fish tank air disperser and the bubbles are much finer now (see pic). After 30 secs the 20L drum was full of foam, but I kept going for 2 mins. I think I probably could have gone for longer as there was still about 1/4 of the liquid charge left. I used 10 ml concentrate to 1000 ml water which generates 10 L foam. Now to try and add the foam to a cement slurry.I guess it is like adding beaten eggwhites, you just fold it in.
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foam concrete-2012-10-13-14.57.33.jpg  

Last edited by david s; 10-12-2012 at 11:21 PM.
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  #39  
Old 10-13-2012, 06:45 AM
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Default Re: foam concrete

David,

Just read your thread on CellCrete, I work for a utility company in the US and we are required to use what we call flowable backfill as compacted materials in pipeline trenches in the city streets (basically low cement based slurry, say one bag mix). We investigated CellCrete as a backfill option but it takes quite a large project for it to be cost effective to bring the equipment in. Cellcrete samples I have show consistent aeration, lightweight, and minimal psi strength (<200 -300 psi) which is good for us since many times we have to go back and dig in the area again. It will be interesting to see how you pioneer project works for an oven. Best of luck.
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  #40  
Old 10-19-2012, 09:27 PM
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Default Re: foam concrete

I did my first trial with the foam concrete and was more than impressed. I chickened out a little and made a 5:1 vermicrete, but replaced half the vermiculite with foam. Because it contained much less vermiculite I was able to drastically decrease the amount of water required. Following the directions on quantity of concentrate the resulting volume of the mix turned out to be exact. The foam is a little difficult to get to mix into the slurry because it tends to want to float on the top. However, on continued mixing I was able to get a consistent mix. Bubbles of air on the surface tend to break easily but those below the surface remain. The stuff is incredibly light and fluffy, easy to pour and level. I now have a slab that has less vermiculite, therefore less water, and presumably a better insulator as air is superior to vermiculite. Also there will be a reduction in the sponge like characteristic of standard vermicrete to hold water, therefore eliminating the excess water will be less of a problem. Before I jump for joy I will wait to see how it goes for strength. I did add reinforcing fibres to assist this as I usually do. Perhaps next time I'll be brave enough to try using just the foam without the vermiculite.
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