Aerated concrete low down

[Bartondad]

I see that some use aerated concrete for their door insulation. Are there other uses for this and how do you aerate it? Do you purchase it already madee or is there a mixing secret? Just need the low sown on this stuff as I consider my build.
thanks
Thom

[kebwi]

Are you referring to vermiculite or perlite based concrete or something else? The vermiculite/perlite blends are used throughout the Pompeii design for insulation, both under the floor on the hearth and over the dome...but perhaps you mean something else by aerated?...

[Bartondad]

Thanks Kebwi-
That's exactly what I was talking about. Do I mix it myself or can I buy a pre mix at my local masonry yard? Also, how thick do I put it on top of my dome/insulation blanket when I get to that point?

[Tscarborough]

Aerated concrete production requires a multi-million dollar facility. Basically it is produced in huge blocks, on the scale of 20'x40'x100' long units which are then sawn into modular units. Structural panels are produced in a similar fashion as prestressed concrete, but regardless you ain't doing it at home.

[kebwi]

Well, Tscar, I agree that the term aerated concrete generally refers to an industrial material, as you are describing, but vermicrete is basically aerated concrete in that is a form of foam (def: gas bubbles trapped in a substrate). Vermicrete insulates for two reasons, the same two reasons the styrofoam insulates. Heat transfers through nearby atoms, so the less dense a material, the more difficult it is for heat to transfer from one atom to the next. Styrofoam has two forms of low density: The polystyrene is a low density material itself and the bubbles it traps, being a gas, are of course extremely low density. Vermicrete works exactly the same way. The vermiculite is low density so the heat doesn't transfer through the vermiculite very effectively. In addition, vermicrete is a foam, it is aerated, and heat has a very hard time transfering through the bubbles.

But I agree with you. I believe the term aerated concrete is usually reserved for a specific substance (something I know practically nothing about), and vermicrete ain't it...to the best of my knowledge.

[kebwi]

Originally Posted by Bartondad

Thanks Kebwi-
That's exactly what I was talking about. Do I mix it myself or can I buy a pre mix at my local masonry yard? Also, how thick do I put it on top of my dome/insulation blanket when I get to that point?

Well, I am as far from an expert as you will find on FB. Many other people are more qualified to answer your questions, but I'll offer what I can.

I think I have heard of buying vermicrete as a mix, but no FBers ever do it that way. It's just so simple to make! Find a source of those four-cubic-foot bags of vermiculite or perlite that everyone on FB discusses. Try to find the larger "grain" sizes, 1/4" to 1/2" (or larger if you can). Get some good old fashioned portland cement. Start making a mess.

Now, your second question is addressed somewhat in the Pomeii directions (a PDF available on the FB website...do you have that yet? If not, GET IT!) and is also discussed elsewhere on FB. I'll try to do a search and post some links to other threads here when I get a chance...but just search the forum for "vermiculite insulation", you'll probably get lots of good stuff.

Cheers!

[Tscarborough]

Autoclaved Aerated Concrete, AKA AAC, AKA Aerated concrete is a specific term designating a specific material. It is produced by creating a reaction in a cementious mixture that produces minute bubbles in the mass of material. Consider it to be the swiss cheese of masonry products.

Perlcerte/vermicucrete are not aerated, they are low density cementious materials that owe their insulation value to the aggregate used.

[dmun]

We've talked about it many times. AAC is the usual description, for aerated autoclaved concrete. It's rare and expensive in the US, and a common building material in Europe, where they care about insulation and energy efficiency. It's sold there under the brand name Hebel, and others.

Aerated autoclaved concrete - Wikipedia, the free encyclopedia

[Bartondad]

Thanks all!

[Tscarborough]

We actually sold quite a bit of it in Central Texas a few years ago. The material is great, but it is new (here), expensive, and the construction techniques used are very different than regular masonry construction.

There were also some issues with the structural panels including a lawsuit that got out us of that market.