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  #261  
Old 10-02-2012, 06:00 AM
david s's Avatar
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Default Re: Starting new 36" build

I recently ordered some "foaming agent" to create foam concrete and have plans to use it to produce a Hebel like product as well as experimenting with it in conjunction with calcium aluminate cement and clay slip, which I hope to use to create fired castings for another project. I eagerly await it's delivery. Normal detergent for this application does not work because apart from not knowing its compatability with Portland cement it deflates too quickly resulting in failure. The product designed specifically for the purpose has been tested for both performance and compatibility so that's what I'll be using. Many of these products may seem to be the same, but they actually vary considerably in composition and performance. When I get it I'll post the chemical name, but it's likely to be a very long one.

Last edited by david s; 10-02-2012 at 06:43 AM. Reason: Typo
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  #262  
Old 10-02-2012, 06:02 AM
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Default Re: Starting new 36" build

Quote:
Originally Posted by wotavidone View Post
P.S. right now my wife has Palmolive dishwashing detergent in the cupboard - the label says it is a micture of anionic and non-ionic surfactants. Non ionic surfactants often are glycosides. i.e the molecule contains a sugar.
I'd think twice about using it as a plasticiser.
Wives are so unreliable. You should have told her you wanted to use it as a super plasticiser.

Cement mixer drivers keep a kilo of sugar in the glove box. If they get stuck the sugar stops the concrete from ever going off. Stays like jelly so it can be removed without the use of dynamite and jackhammers.

Last edited by david s; 10-02-2012 at 06:10 AM.
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  #263  
Old 10-02-2012, 06:28 AM
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Default Re: Starting new 36" build

Gulf,

My step son is a concrete engineer who works in an industrial concrete lab and he pick up a 500 ml bottle of SuperPlastizer for me. Your question on this topic has sparked quite a debate. I am by no means a concrete person or "finisher" so I am sitting on the sidelines on this topic
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  #264  
Old 10-02-2012, 04:14 PM
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Join Date: May 2011
Location: South Australia
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Default Re: Starting new 36" build

Quote:
Originally Posted by david s View Post
I recently ordered some "foaming agent" to create foam concrete and have plans to use it to produce a Hebel like product as well as experimenting with it in conjunction with calcium aluminate cement and clay slip, which I hope to use to create fired castings for another project. I eagerly await it's delivery. Normal detergent for this application does not work because apart from not knowing its compatability with Portland cement it deflates too quickly resulting in failure. The product designed specifically for the purpose has been tested for both performance and compatibility so that's what I'll be using. Many of these products may seem to be the same, but they actually vary considerably in composition and performance. When I get it I'll post the chemical name, but it's likely to be a very long one.
Detergent certainly would not work on its own as a foaming agent for creating a Hebel like product.
The issue, apart from strength/longevity, is that, while detergent can alter the surface tension of water, making it possible to blow nice big soap bubbles, it doesn't actually generate any gas to inflate those bubbles.
So, if you just use something to alter the ability of the concrete slurry to hold bubbles, then you'd have to vigorously agitate it to introduce lots of air.
According to my reading, Hebel was created using aluminium powder (about 2%?) to react with the lime in the concrete. Apparently this reaction generates hydrogen gas, which leads to foaming the concrete. The hebel is then autoclaved to set the cement before the foamed concrete collapses.
I suggest your proprietry foamer will need two components, one to do the surface tension altering thing so bubbles can be formed, and one to provide the gas to inflate those bubbles.
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  #265  
Old 10-02-2012, 07:04 PM
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Default Re: Starting new 36" build

Foaming agents/soaps are detrimental to concrete using portland cement, I have no information on calcium aluminate cement use with them. AAC is not created with a foaming agent per se.
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  #266  
Old 10-02-2012, 07:17 PM
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Default Re: Starting new 36" build

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Originally Posted by Tscarborough View Post
Foaming agents/soaps are detrimental to concrete using portland cement, I have no information on calcium aluminate cement use with them. AAC is not created with a foaming agent per se.
I guess it depends how you define a foaming agent. Is it something that has a chemical reaction and causes things to foam, or is it a substance that changes the surface tension of the water in the mix (e.g. detergent or lignosulphonate) so that if you agitate it or in some other way entrain extra air, it hangs onto the bubbles?

From the wiki entry on AAC:

"AAC is produced using no aggregate larger than sand. Quartz sand, lime, and/or cement and water are used as a binding agent. Aluminum powder is used at a rate of 0.05%0.08% by volume (depending on the pre-specified density). When AAC is mixed and cast in forms, several chemical reactions take place that give AAC its light weight (20% of the weight of concrete) and thermal properties. Aluminum powder reacts with calcium hydroxide and water to form hydrogen. The hydrogen gas foams and doubles the volume of the raw mix (creating gas bubbles up to 3mm (⅛ inch) in diameter). At the end of the foaming process, the hydrogen escapes into the atmosphere and is replaced by air."

That makes the aluminium a foaming agent to me. It does not however mean its a material that alters the surface tension of the water so as to enable the entrainment of extra air, which I think is also a definition of a foaming agent.

So it depends, I guess. It will be very interesting to see what the foaming agent David has ordered actually contains, and wther it will actually enable him to make a homebrew aerated concrete.
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  #267  
Old 10-02-2012, 07:27 PM
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Default Re: Starting new 36" build

I guess, but to me a foaming agent is like soap, that is it doesn't produce foam, it encourages it.
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  #268  
Old 10-02-2012, 08:13 PM
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Default Re: Starting new 36" build

The foaming agent I'm getting is designed specifically for use with Portland cement. It requires mechanical agitation to create the foam, rather than a chemical reaction like Hebel. You use a "foam generator", which I hope to build cheaply using compressed air as the driver.once the foam is formed it is mixed into the cement slurry.
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  #269  
Old 10-02-2012, 08:23 PM
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Default Re: Starting new 36" build

I have tried AAC in direct flame contact, it does not survive. I am interested in your results with foamed refractory cement.
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  #270  
Old 10-02-2012, 08:36 PM
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Default Re: Starting new 36" build

Yes, I'll let you know how I go. I will start another thread about it. I feel guilty that we've hijacked Deyjaryo's thread of his build.
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