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Post by rectifier on Nov 18, 2011 18:50:09 GMT -8
For some reason I was looking at the wikipedia R-values article, and these numbers from the table popped out at my eye: Air-entrained concrete: R-3.9 Fiberglass batts: R-3.1 - 4.3 Perlite (loose fill): R-2.7 Poured concrete: R-0.08 Seeing how loose fill perlite is more than insulating enough for a heat riser... I looked into air-entrained concrete a bit and it looks easy to make by just adding a surfactant and stirring, and, of course, it would be extremely cheap compared to refractory materials. Also, it's billed as being resistant to freeze/thaw cycles, which means it could be good at withstanding the thermal stresses of heat riser duty. Anyone ever handled it? Edit: A bit more research, www.schundler.com/air&pumps.htm talks about a perlite/vermiculite air entrained mix that is 'lightweight and insulating' and can be used for 'oven insulation' as well as 'cryogenic storage tanks'. It is resistant to cracking due to thermal cycling. This is definitely worth looking into, I think. |
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Post by mintcake on Nov 23, 2011 10:13:27 GMT -8
I thought concrete had a max temperature of only a few hundred degrees before it started disintegrating?
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Deleted
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Post by Deleted on Nov 23, 2011 10:30:40 GMT -8
It is only a matter of the mixture whether it will degrade or not. Just adding some hydrated lime will make it a bit more resistant. Fire cement contains a lot of alumina and calcium aluminate. en.wikipedia.org/wiki/Calcium_aluminate_cements |
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Post by jislizard on Apr 28, 2012 21:34:27 GMT -8
Any particular chemicals for entraining?
From what I could understand, mixing perlite and cement will have insulating properties but entraining will preserve the air bubbles on the surface of the perlite and be evem more efficient.
I couldn't find any info on what chemical to use except a few from overseas, if it is just a surfactant I would have thought it would have the opposite effect of breaking down the surface tension on the perlite and releasing the airbubbles.
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Post by gavinguy on Jan 25, 2013 16:24:56 GMT -8
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Post by satamax on Feb 26, 2013 13:55:45 GMT -8
Hey guys.
Well, if this is the same stuff as "béton cellulaire" Ytong claims their blocs are resistant up to 1200c° I might have to grab some to see what i can do with dem!
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morticcio
Full Member
"The problem with internet quotes is that you can't always depend on their accuracy" - Aristotle
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Post by morticcio on Feb 27, 2013 9:49:35 GMT -8
Ytong claims their blocs are resistant up to 1200c° Resistant to 1200°C but for how long? They're not designed to see the hot face e.g. lining the burn tunnel/riser etc. Probably okay used as an insulative backup lining or foundation? |
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dvawolk
Full Member
DSR2 125mm open system (actual project)
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Post by dvawolk on Feb 27, 2013 10:48:08 GMT -8
I used ytong exactly for the heat riser and for the ceiling of batchbox horizontal feed. Thickness 5cm (2 in). The ceiling cracked on its own in a few firings.
The heat riser was holding together pretty untill i started to move it a bit. I wouldn't use it in heatriser that is hardly reachable... Otherwice i might give it a try (say if under a removable barrel...
Klemen
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Post by stephenson1 on Feb 28, 2013 4:56:40 GMT -8
Hi everyone. I just found a recipe for homemade refractory mix: www.backyardmetalcasting.com/refractories.htmlI also found a local supplier that sells Portland I-A which has "air-entraining" additives. Does anyone know if this be useful as the portland cement portion of the recipe? |
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Post by satamax on Aug 30, 2014 20:09:32 GMT -8
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Deleted
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Post by Deleted on Aug 31, 2014 6:53:24 GMT -8
For fire protection it does not much matter it needs to be discarded later,
but a stove should remain usable.
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Post by satamax on Aug 31, 2014 7:07:22 GMT -8
Yes Kark.
I will try it one of thoses days in the batch rocket barbie i made. Since the firebox is too big. To reduce it's size. It doesn't matter much in there, because i will be able to change the AAC pannels when worn out!
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