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Aerated concrete is extremely popular in Kazakhstan and Russia in private houses. It's cheaper than bricks, it's sturdy enough, it provides good insulation, it

Aerated concrete is extremely popular in Kazakhstan and Russia in private houses. It's cheaper than bricks, it's sturdy enough, it provides good insulation, it does not require much skill to use, pieces are huge, so it's much faster to build. There are drawbacks, of course, but overall it's a very popular technology.

bolangi 5y ago
I know a guy who researched aerated concrete. He used a slimy additive to help hold the bubbles. Basically, the compression strength of concrete is so much higher than necessary that addition of a large portion of air results in a material that is much lighter with more than adequate compression strength. He couldn't find interest among concrete companies in his state.
elihu 5y ago
I think in the U.S. the only place that makes the stuff (Aercon) is in Florida, and there's Hebel that has a plant in Mexico near Texas.
jessaustin 5y ago
...it provides good insulation... This might be true, but it would be surprising, since even "aerated" concrete would still be made of highly thermally conductive... concrete.
- R0b0t1 5y ago
  The thermal mass of your house is part of the perceived insulation. In the desert especially nights are cold, the house chills, and retains that chill throughout the day, keeping it cool inside.
  - earleybird 5y ago
    Thermal mass to manage comfort could be seen as tuning latency for your arrival and departure of your heat packets.
- elihu 5y ago
  If memory serves, normal concrete has an R value of about 1 per foot, whereas AAC is more like 1 to 2 per inch. So, an 8 inch wall would have an R-value of about 8-16. That doesn't seem like enough for a cold climate, so I'd assume for those applications you'd probably add an extra layer of actual insulation. (This would mean having pretty thick walls.) You wouldn't need as much supplemental insulation as you would with a regular concrete wall, though. The thermal mass is also nice, though it doesn't really help much in winter-time. I think AAC is a bit more suited to warm desert climates where you have a daily hot/cold cycle.
  - vbezhenar 5y ago
    20-inch wall is enough for pretty cold climate according to my calculations. Either that or thin wall with insulation (or thin wall and more money on heating which might be an acceptable solution, if you have cheap coal and your country does not care what you build).
  - PaulDavisThe1st 5y ago
    Fairly sure that AAC has less thermal mass than regular concrete. It's more air, less concrete, and the thermal mass comes from the concrete.
    - elihu 5y ago
      Yeah, that sounds right. Still, a lot less than concrete can still be a lot. And I think in most cases I'd rather have better insulation than more thermal mass.
- orthoxerox 5y ago
  Here in Russia it usually requires an external layer of insulation plus cladding, you don't just stucco it and call it a day. I did the math and a wall two blocks thick should be barely sufficient, but needs a vapour barrier inside, or the dew point will be inside the wall, ruining it. A vapour barrier and a drywall finish means no reduction in construction costs.
fpoling 5y ago
In has been popular in the whole former USSR. But for some reason in past it was not considered as a suitable material for houses, only for storage facilities etc. But it could be just a cultural perception. For example, my father built a temporary house from it in Belarus in 1980s while waiting for the main house construction that was using ordinary bricks. I remember as a child that building from aerated concrete was indeed very quick affair.
- ArkanExplorer 5y ago
  Disadvantages From Wikipedia: "Installation during rainy weather: AAC is known to crack after installation, which can be avoided by reducing the strength of the mortar and ensuring the blocks are dry during and after installation. Brittle nature: they need to be handled more carefully than clay bricks to avoid breakage. Attachments: the brittle nature of the blocks requires longer, thinner screws when fitting cabinets and wall hangings and wood-suitable drill bits or hammering in. Special, large diameter wall plugs (anchors) are available at a higher cost than common wall plugs. Insulation requirements in newer building codes of northern European countries would require very thick walls when using AAC alone. Thus many builders choose to use traditional building methods installing an extra layer of insulation around the entire building." https://en.wikipedia.org/wiki/Autoclaved_aerated_concrete https://en.wikipedia.org/wiki/Autoclaved_aerated_concrete
kingsuper20 5y ago
>Aerated concrete is extremely popular in Kazakhstan and Russia in private houses. In California (FWIW), I expect that you hit seismic issues.
- Gibbon1 5y ago
  Problem in California is insane mandated R values for walls. Aerated concrete can meet previous standards. But not the new ones. So it's use is effectively banned. Old saw about Generals fighting the last war. Energy efficiency standards assume the need to conserve limited supplies for fossil fuels. And the need to not interfere with building large houses for upper middle class people. Bad thing is R value is a metric designed to upsell insulation. R30 insulation is twice as good as R15, if you're the guy selling it. If you're the guy buying it, not as much.
  - falcolas 5y ago
    Considering that you can put foam on the inside and outside of walls (exceptionally common in high-efficiency homes), this is likely not the issue.
    - Gibbon1 5y ago
      I run my furnace for 5 months out of the year. Total yearly cost for nat gas is about $600. And my house is a really drafty 1950's era one. So the max that insulation could save me is $600, that's it. A heat pump and solar installation needed heat my house in the winter would cost about $12000. But actually the heat pump would only run as I mentioned above for 5 months out of the year. So really just to offset the energy, $6000. Economically high performance insulation systems lose to solar panels. That wasn't true 10 years ago. But it's true now. And it'll get worse going forward.
      - falcolas 5y ago
        When you're building a house, it's not hard to add additional insulation on either side of the framing. Not terribly expensive, either. You also save on the installation of the furnace (and AC) because it just requires very little heating and cooling. Since insulation is low maintenance, you'll get those savings over the whole lifespan of the house. Now, if you're in an existing house, it likely doesn't make sense to tear down all your siding and drywall just to add insulation, since you're having to both demo and build.
falcolas 5y ago
Can you pre-tension aerated concrete? Concrete is already poor in tensile strength, it feels like creating voids in it would only make that worse. And tensile strength is largely required for larger, earthquake safe concrete fixtures.
- vbezhenar 5y ago
  AFAIK for earthquake-safe buildings you're supposed to build a frame from an ordinary reinforced concrete and then fill walls with blocks from aerated concrete. Not sure about details, I'm not living in earthquake-dangerous area, so never had to research more about it.

bolangi 5y ago

I know a guy who researched aerated concrete. He used a slimy additive to help hold the bubbles. Basically, the compression strength of concrete is so much higher than necessary that addition of a large portion of air results in a material that is much lighter with more than adequate compression strength. He couldn't find interest among concrete companies in his state.

elihu 5y ago

I think in the U.S. the only place that makes the stuff (Aercon) is in Florida, and there's Hebel that has a plant in Mexico near Texas.

jessaustin 5y ago

...it provides good insulation... This might be true, but it would be surprising, since even "aerated" concrete would still be made of highly thermally conductive... concrete.

R0b0t1 5y ago
The thermal mass of your house is part of the perceived insulation. In the desert especially nights are cold, the house chills, and retains that chill throughout the day, keeping it cool inside.
- earleybird 5y ago
  Thermal mass to manage comfort could be seen as tuning latency for your arrival and departure of your heat packets.
elihu 5y ago
If memory serves, normal concrete has an R value of about 1 per foot, whereas AAC is more like 1 to 2 per inch. So, an 8 inch wall would have an R-value of about 8-16. That doesn't seem like enough for a cold climate, so I'd assume for those applications you'd probably add an extra layer of actual insulation. (This would mean having pretty thick walls.) You wouldn't need as much supplemental insulation as you would with a regular concrete wall, though. The thermal mass is also nice, though it doesn't really help much in winter-time. I think AAC is a bit more suited to warm desert climates where you have a daily hot/cold cycle.
- vbezhenar 5y ago
  20-inch wall is enough for pretty cold climate according to my calculations. Either that or thin wall with insulation (or thin wall and more money on heating which might be an acceptable solution, if you have cheap coal and your country does not care what you build).
- PaulDavisThe1st 5y ago
  Fairly sure that AAC has less thermal mass than regular concrete. It's more air, less concrete, and the thermal mass comes from the concrete.
  - elihu 5y ago
    Yeah, that sounds right. Still, a lot less than concrete can still be a lot. And I think in most cases I'd rather have better insulation than more thermal mass.
orthoxerox 5y ago
Here in Russia it usually requires an external layer of insulation plus cladding, you don't just stucco it and call it a day. I did the math and a wall two blocks thick should be barely sufficient, but needs a vapour barrier inside, or the dew point will be inside the wall, ruining it. A vapour barrier and a drywall finish means no reduction in construction costs.

fpoling 5y ago

In has been popular in the whole former USSR. But for some reason in past it was not considered as a suitable material for houses, only for storage facilities etc. But it could be just a cultural perception. For example, my father built a temporary house from it in Belarus in 1980s while waiting for the main house construction that was using ordinary bricks. I remember as a child that building from aerated concrete was indeed very quick affair.

ArkanExplorer 5y ago
Disadvantages From Wikipedia: "Installation during rainy weather: AAC is known to crack after installation, which can be avoided by reducing the strength of the mortar and ensuring the blocks are dry during and after installation. Brittle nature: they need to be handled more carefully than clay bricks to avoid breakage. Attachments: the brittle nature of the blocks requires longer, thinner screws when fitting cabinets and wall hangings and wood-suitable drill bits or hammering in. Special, large diameter wall plugs (anchors) are available at a higher cost than common wall plugs. Insulation requirements in newer building codes of northern European countries would require very thick walls when using AAC alone. Thus many builders choose to use traditional building methods installing an extra layer of insulation around the entire building." https://en.wikipedia.org/wiki/Autoclaved_aerated_concrete https://en.wikipedia.org/wiki/Autoclaved_aerated_concrete

kingsuper20 5y ago

>Aerated concrete is extremely popular in Kazakhstan and Russia in private houses. In California (FWIW), I expect that you hit seismic issues.

Gibbon1 5y ago
Problem in California is insane mandated R values for walls. Aerated concrete can meet previous standards. But not the new ones. So it's use is effectively banned. Old saw about Generals fighting the last war. Energy efficiency standards assume the need to conserve limited supplies for fossil fuels. And the need to not interfere with building large houses for upper middle class people. Bad thing is R value is a metric designed to upsell insulation. R30 insulation is twice as good as R15, if you're the guy selling it. If you're the guy buying it, not as much.
- falcolas 5y ago
  Considering that you can put foam on the inside and outside of walls (exceptionally common in high-efficiency homes), this is likely not the issue.
  - Gibbon1 5y ago
    I run my furnace for 5 months out of the year. Total yearly cost for nat gas is about $600. And my house is a really drafty 1950's era one. So the max that insulation could save me is $600, that's it. A heat pump and solar installation needed heat my house in the winter would cost about $12000. But actually the heat pump would only run as I mentioned above for 5 months out of the year. So really just to offset the energy, $6000. Economically high performance insulation systems lose to solar panels. That wasn't true 10 years ago. But it's true now. And it'll get worse going forward.
    - falcolas 5y ago
      When you're building a house, it's not hard to add additional insulation on either side of the framing. Not terribly expensive, either. You also save on the installation of the furnace (and AC) because it just requires very little heating and cooling. Since insulation is low maintenance, you'll get those savings over the whole lifespan of the house. Now, if you're in an existing house, it likely doesn't make sense to tear down all your siding and drywall just to add insulation, since you're having to both demo and build.

falcolas 5y ago

Can you pre-tension aerated concrete? Concrete is already poor in tensile strength, it feels like creating voids in it would only make that worse. And tensile strength is largely required for larger, earthquake safe concrete fixtures.

vbezhenar 5y ago
AFAIK for earthquake-safe buildings you're supposed to build a frame from an ordinary reinforced concrete and then fill walls with blocks from aerated concrete. Not sure about details, I'm not living in earthquake-dangerous area, so never had to research more about it.