Note that aircrete itself has existed for decades, but production of aircrete has typically required buying (or DIY-ing) a high-capacity foam generator.
What's novel in this video is the production method, which uses only a standard cement mixer.
Aerated concrete is an established building material in some parts of the world. In Europe, a big manufacturer is Ytong, and they even make precast panels in addition to blocks.
It's made differently from this, though. It is aerated through a chemical reaction rather than mechanically.
The industrial version is produced in an autoclave, this allows precise control of curing, density and final mechanical resistance/insulation values. Hence, the name the material is best known by - AAC.
On the other hand, the video linked attributes too much credit and complexity to the foam manufacturing method, it can certainly be done with very primitive technology. Here are some dudes doing it in a developing country, it's very very basic, the foam generator is basically a steel wool sponge where pressurized air combine with water containing the foaming agent. They give out the complete recipe and details of their tools:
There was recently a crisis in older publicly constructed buildings in the UK that were built [0].The aerated concrete had a limited lifespan especially if it was damaged and had contact with water.
Lots of people looking for compensation and claiming mis-representation.
The UK crisis involved steel reinforced AAC beams that were used (of all places) to support roofs of schools. UK turned out to be a rainy place, the rain infused into the cellular structure and corroded the steel, with disastrous consequences.
It's a very particular use case of a very particular product, not relevant to the wide majority of AAC uses around the world, which is largely non-structural and not reinforced, or subjected to moderate compressive loads, such as lateral walls for 1-2 stories buildings in non-seismic areas.
The risks were understood (by engineers) and this usage was given a "shelf life". Unfortunately, those risks were put into the "Oh we'll forget about it" or "We'll wait until it looks a bit shifty" categories.
However as any fule (engineer) kno, reinforced and especially pre-stressed conc members will fail in quite a dramatic fashion. Unless you notice rust dribbling out then you can end up with anything from the roof failing to the roof exploding. I don't think anyone was daft enough to pre-stress these things.
I don't know how much money was saved but it was a really stupid application and basically ended up punting far greater costs due to remediation down the road.
While it might technically be true, that surely does not absolve the engineers who did this crap.
There is a general social expectation that new buildings should be structurally sound for a duration on the order of a century. So, if you deliver something that has a mean time before catastrophic failure around 30 years, you also need to account and set up the institutions that will handle the failure, the same way nuclear companies are required to set aside money for their decommissioning. You need to have periodic inspections for signs of early failure etc. and this whole circus needs to be disclosed and priced into your tender.
In reality, this entire fiasco was a dirty and cheapest way to satisfy the contract, ye old "good enough for government work" as evidenced by the fact no substantial number of private buildings of the same period are having this problem.
The maintenance provision was snuck into - or bribed into - some mountain of legalese, but the fuckers knew exactly that they were putting children in harm's way.
I heard about aerogel as a kid and only recently learned how extremely hard it is to make [0], so this seems like a cool and more accessible material in the same vein.
I saw this days ago. The problem is validating strength and integrity over time. That sort of long-term follow-up and scientific, repeatable destructive testing doesn't fit into a short video. Evangelizing unproven construction methods and materials is reckless without context and nuance.
When an office building was built in any earthquake-prone area that housed a nuclear engineering consultancy I worked in for several years, multiple test specimens of concrete were poured and kept for later testing and evaluation, and extra ones were kept should there ever be a question about the concrete's quality in the future.
Aircrete is far too fragile and will not hold tolerance. There is a shit towards ultra high performance concrete but that’s a completely different material.
Just started watching this, but if anyone has seen similar material used for some form of retaining wall (even 1-4' high), I'd be happy to hear about it. Got a lot of slope to deal with, and materials for attractive retaining walls add up.
Concrete is cement plus aggregate (it doesn't have to be sand; it could be gravel, for example). Coarse aggregates wouldn't work well in this, but it would be cool for a followup video where sand is used.
The wikipedia pages suggests that this is more prolery referred to as "foam mortar" or "foam cement"
You could say the aggregate is air and the cement still performs its role as a binder, it binds all the air bubbles into a stable matrix. Hence "aerated concrete".
Has this particular reaction been around? The news isn’t the end result. The news is he does it in a new way (that does not require large upfront investments).
I like the idea of a lightweight concrete like material that can be used to make houses more durable. Is there a way to replace drywall interiors with this or something else? I really hate how susceptible drywall is to things like moisture and mold, but also how repairing it requires a dusty and messy process of cutting, sanding, mud, tape, and all that. It would be so much easier to have waterproof durable panels that can be opened to access the interior wall spaces (for electrical or plumbing stuff). Is there a solution?
It really is amazing, you can build a whole 2-story house out of it quickly using polymer-based glue instead of mortar, only using traditional reinforced concrete in some critical places. Was quite popular in russia, last I checked. Unfortunately hard to find in some better CIS countries.
Yes, about 60% of all new single-family homes are built out of AAC in Russia. It's also very common as an infill in reinforced concrete frames, like blocks of flats.
There are AAC factories in Ukraine, Belarus, Kazakhstan that I know of. The rest are probably too seismically risky to be major AAC markets.
Didn’t really study this aspect, but it feels like thick AAC blocks would be better for seismic stability than those tuff stone blocks popular in Armenia. It’s lighter, glues to neighboring blocks better due to perfect shape, and has better heat insulation.
It would be amazing if AAC-like material could be produced on-site economically to create a lighter form of monolithic reinforced concrete construction, like filling a formwork with expanding foam.
You can also build brick walls without mortar, some of them even contain insulation, you just need to plaster both sides and you're good to go. Porothern dry fix is a good example
I had the choice between aircrete and that for my house and went for good ol bricks instead
Fuck aircrete. My house has aircrete blocks in the extension and you need special expensive wall plugs to attach things to it that are rated to a grant total of 25kgf.
Because nobody would want to actually hang heavy things on their wall right??
Most people aren't hiring professionals to put up shelves lol. And there is no "how to deal with the wall". It's fundamentally weak. Best you can do is Rigifix M8 bolts which are rated to about 25kgf as I said.
Those seem to be for drywall. The strongest option is using resin to install some threaded rod, eg fis-v which is rated to 43kgf (shear load) in the lower of the two rated aircrete classes. That's because it spreads through the holes and therefore has a larger surface area of interface. The downside is that it's not removable.
That seems really low for shear. The M8 Rigifix say 245 kgf for 1mm displacement in shear.
Also I slightly misremembered the rating for pull-out - actually in 34 kgf, and they are applying a fairly generous 15% safety factor (i.e. tested ultimate strength was 224 kgf). But still, it sucks that you can't just use a normal wall plug and have to worry about this sort of thing.
That's 0.43 kN which is 430N or ~43kgf. Comparing to the rigifix table they are using a heavier aircrete and a smaller safety factor, which would take fix-v up to 80kg but that's still a big difference. I wonder if there is a testing methodology difference, as usually resin fixings are considered stronger than plug fixings.
If it's just a threaded rod held in with resin then I expect the difference is in the hole size. The actual wall plug for the M8 Rigifix is 16mm diameter. Also the M8 bolt is inserted into a larger metal sleeve so it's less likely to bend. I don't know if that affects things though.
What's novel in this video is the production method, which uses only a standard cement mixer.
The 'traditional' method is here: https://www.youtube.com/watch?v=tnNua21zx78
It's made differently from this, though. It is aerated through a chemical reaction rather than mechanically.
On the other hand, the video linked attributes too much credit and complexity to the foam manufacturing method, it can certainly be done with very primitive technology. Here are some dudes doing it in a developing country, it's very very basic, the foam generator is basically a steel wool sponge where pressurized air combine with water containing the foaming agent. They give out the complete recipe and details of their tools:
https://www.youtube.com/watch?v=-h6zBbVkuQI
Lots of people looking for compensation and claiming mis-representation.
[0] https://www.bbc.co.uk/news/education-66669239
It's a very particular use case of a very particular product, not relevant to the wide majority of AAC uses around the world, which is largely non-structural and not reinforced, or subjected to moderate compressive loads, such as lateral walls for 1-2 stories buildings in non-seismic areas.
However as any fule (engineer) kno, reinforced and especially pre-stressed conc members will fail in quite a dramatic fashion. Unless you notice rust dribbling out then you can end up with anything from the roof failing to the roof exploding. I don't think anyone was daft enough to pre-stress these things.
I don't know how much money was saved but it was a really stupid application and basically ended up punting far greater costs due to remediation down the road.
While it might technically be true, that surely does not absolve the engineers who did this crap.
There is a general social expectation that new buildings should be structurally sound for a duration on the order of a century. So, if you deliver something that has a mean time before catastrophic failure around 30 years, you also need to account and set up the institutions that will handle the failure, the same way nuclear companies are required to set aside money for their decommissioning. You need to have periodic inspections for signs of early failure etc. and this whole circus needs to be disclosed and priced into your tender.
In reality, this entire fiasco was a dirty and cheapest way to satisfy the contract, ye old "good enough for government work" as evidenced by the fact no substantial number of private buildings of the same period are having this problem.
The maintenance provision was snuck into - or bribed into - some mountain of legalese, but the fuckers knew exactly that they were putting children in harm's way.
[0] https://www.youtube.com/watch?v=Y0HfmYBlF8g
When an office building was built in any earthquake-prone area that housed a nuclear engineering consultancy I worked in for several years, multiple test specimens of concrete were poured and kept for later testing and evaluation, and extra ones were kept should there ever be a question about the concrete's quality in the future.
This video makes aircrete with cement + water + thickening/foaming agent, but it doesnt use any sand, no?
Another method: https://www.youtube.com/watch?v=tnNua21zx78
The wikipedia pages suggests that this is more prolery referred to as "foam mortar" or "foam cement"
https://en.wikipedia.org/wiki/Foam_concrete
There are AAC factories in Ukraine, Belarus, Kazakhstan that I know of. The rest are probably too seismically risky to be major AAC markets.
It would be amazing if AAC-like material could be produced on-site economically to create a lighter form of monolithic reinforced concrete construction, like filling a formwork with expanding foam.
I had the choice between aircrete and that for my house and went for good ol bricks instead
Because nobody would want to actually hang heavy things on their wall right??
Cabinets
Shelves
Large mirrors
Pot racks
https://www.buyrigifixonline.co.uk/rmd.pdf
> 43kgf (shear load)
That seems really low for shear. The M8 Rigifix say 245 kgf for 1mm displacement in shear.
Also I slightly misremembered the rating for pull-out - actually in 34 kgf, and they are applying a fairly generous 15% safety factor (i.e. tested ultimate strength was 224 kgf). But still, it sucks that you can't just use a normal wall plug and have to worry about this sort of thing.
That's 0.43 kN which is 430N or ~43kgf. Comparing to the rigifix table they are using a heavier aircrete and a smaller safety factor, which would take fix-v up to 80kg but that's still a big difference. I wonder if there is a testing methodology difference, as usually resin fixings are considered stronger than plug fixings.