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We use this a lot to support landscaping in the sky (rooftop terraces and such on high rises) which is an architectural trend that really needs to go away. Ther

by ggcdn 5y ago

We use this a lot to support landscaping in the sky (rooftop terraces and such on high rises) which is an architectural trend that really needs to go away. There is nothing green or sustainable about the extra concrete needed to support it. But the alternative to geofoam is usually clean fill, like sand, which weighs about 110 lb/cf. contractors ask to substitute it because it’s cheaper, but it almost always results in thicker structure and more rebar to support it.

BugsJustFindMe 5y ago
> But the alternative to geofoam is usually clean fill, like sand, which weighs about 110 lb/cf. Why not aircrete?
- ggcdn 5y ago
  Not sure, it’s not been proposed on our projects before. Most likely, that means it’s not cheaper than geofoam or fill.
  - baybal2 5y ago
    Very likely it's just no contractors dealing with it. I read up on it when we did electronics for concrete mixers. The chemistry of foam concrete is a very inexact science, bordering on being "possible to get right through talent only" Very little literature on it, and proprietary foaming agents all come from Eastern Europe with zero info, or instructions beyond "mix this stuff with water 100:1, and pray"
    - Arrath 5y ago
      Yeah, that lines up with my experience with that crap. It's been a massive headache.
- Arrath 5y ago
  I'm involved with a project using a form of aircrete right now, and we're having a right hell of a time with proper curing and temperatures (to be fair some of that is due to an outrageous spec), as well as mixer truck dwell times, and even input aggregate temperatures. E.G. we had to bring in a refrigerated semi-trailer to store the sand to ensure it was cool enough to make the mix during this heat wave. We are, in fact, trying to convince the owner to let us put in geofoam in place of the specified aircrete. It's much, much easier to bring in a trailer of geofoam blocks, place and size them then compared to pouring a lift of concrete and ensuring proper aeration, vibration, temperatures, etc.
  - BugsJustFindMe 5y ago
    If you're not making your own geofoam on site, it seems like the fair comparison should be bringing in a trailer of aircrete blocks made elsewhere in controlled conditions instead of being made to mix it yourself. Any idea why nobody makes them?
    - Arrath 5y ago
      A quick google turns up a handful of suppliers, so some outfits do make them. May not be available for all use cases, though. https://tarmac.com/products/blocks/aircrete-blocks/#all?pl1_p=1&p_scr=3234 https://tarmac.com/products/blocks/aircrete-blocks/#all?pl1_...

by ggcdn 5y ago

BugsJustFindMe 5y ago

> But the alternative to geofoam is usually clean fill, like sand, which weighs about 110 lb/cf. Why not aircrete?

ggcdn 5y ago
Not sure, it’s not been proposed on our projects before. Most likely, that means it’s not cheaper than geofoam or fill.
- baybal2 5y ago
  Very likely it's just no contractors dealing with it. I read up on it when we did electronics for concrete mixers. The chemistry of foam concrete is a very inexact science, bordering on being "possible to get right through talent only" Very little literature on it, and proprietary foaming agents all come from Eastern Europe with zero info, or instructions beyond "mix this stuff with water 100:1, and pray"
  - Arrath 5y ago
    Yeah, that lines up with my experience with that crap. It's been a massive headache.
Arrath 5y ago
I'm involved with a project using a form of aircrete right now, and we're having a right hell of a time with proper curing and temperatures (to be fair some of that is due to an outrageous spec), as well as mixer truck dwell times, and even input aggregate temperatures. E.G. we had to bring in a refrigerated semi-trailer to store the sand to ensure it was cool enough to make the mix during this heat wave. We are, in fact, trying to convince the owner to let us put in geofoam in place of the specified aircrete. It's much, much easier to bring in a trailer of geofoam blocks, place and size them then compared to pouring a lift of concrete and ensuring proper aeration, vibration, temperatures, etc.
- BugsJustFindMe 5y ago
  If you're not making your own geofoam on site, it seems like the fair comparison should be bringing in a trailer of aircrete blocks made elsewhere in controlled conditions instead of being made to mix it yourself. Any idea why nobody makes them?
  - Arrath 5y ago
    A quick google turns up a handful of suppliers, so some outfits do make them. May not be available for all use cases, though. https://tarmac.com/products/blocks/aircrete-blocks/#all?pl1_p=1&p_scr=3234 https://tarmac.com/products/blocks/aircrete-blocks/#all?pl1_...