[Reference: aerblock.com and phone interview with Michael Baron who has over 20 years’ experience with this material.]
AAC or Autoclaved Aerated Cement and other cementitious technologies started in Sweden 85 years ago and has been in the States and Mexico (where manufacture often takes place) for 2 decades. Michael Baron of aerblock.com has been working with AAC and has observed its progress in North America for over 20 years, although worldwide, especially in Europe and Scandinavia, it has been available longer.
In many ways AAC, which is made into blocks, slabs and panels of varying shapes, sizes and utilities, may be “the best” building material so far discovered for homes, businesses and larger projects because of its many positive properties and its ease of use. It is made from fine silica sand, Portland cement, lime, and aluminum powder, which acts as an expansion agent that releases hydrogen gas in the form of tiny bubbles created by the chemical reaction of the ingredients when mixed with water into a mud-like grey or white slurry that is poured into reusable forms to dry and harden. Then they are cut into precision blocks and steam cured in a pressurized autoclave for a dozen hours or more to complete the chemical process. Because of high demand, they are then wrapped and immediately shipped to waiting building sites around the world to begin construction, from the basement up to and including the roof.
The properties that make Autoclaved Aerated Cement blocks so useful are the following:
- It’s lightweight, about 1/5th that of concrete so it floats in water and is easy to use, speeding up build time.
- AAC can be engineered for seismic and hurricane zones by adding steel cages as reinforcement within the block.
- It’s an inert substance that is load-bearing and is both non-flammable and fire-resistant.
- AAC is non-toxic with none of the poisonous off gassing that is prevalent with many other building materials.
- The air bubbles suspended in the concrete gives AAC good thermal insulative properties for energy efficiency.
- AAC is also sound absorptive, blocking some 70 to 80% of noise penetration.
- AAC is impervious to insect pests and rodents, as well as mold.
- An AAC System creates a vapor-permeable building system which breathes but does not allow moisture to penetrate the interior of the building.
- Its versatility as a building material allows it to be cut with a saw, drilled, shaped, and sanded with hand or power tools, allowing chases (grooves) for plumbing and electrical wires, as well as accepting both nails and screws.
- Labor costs are reduced because these materials are easy-build and structures go up quickly.
- Some blocks interlock, while a thin-set mortar provides a sufficiently tight bond between smooth blocks.
- AAC is a legacy building material that is extremely long-lasting and durable, as well as strong before the elements.
- Even the manufacturing of AAC is pollution-free and resources usage (insulative and structural wood, connective hardware, electricity and water) are minimized.
So AAC is leading the way into a more sustainable future.
In a phone interview on Feb 23, 2021 with Michael Baron, owner of Aerblock.com, Michael revealed that there are many promising new products that are being developed in his Los Alamos laboratory and in the manufacturing facility in Monterey, Mexico for North American consumption. Two such products are:
A) Pourable “foam cement” for filling preset building forms is nearing market readiness, and
B) SIP-like panels with wood or metal frame structures built into them are also under development.
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Europe is way ahead of the US on AAC with Aircrete Europe, currently claiming to be the only Flat-Cake Panel System. Their website (aircrete.com) introduces themselves with the following quote:
“Aircrete Europe is the distinct global leader in the AAC panel market. One of the most important innovations brought to the market by Aircrete is the Flat-Cake cutting technology which allows for the production of the largest variety of AAC products (including thin panels) with high dimensional accuracy and SUPER SMOOTH surfaces to minimize finishing requirements.” (Stucco can be added to the surface for texture, but simple sanding and painting is sufficient.)
Because aircrete is a high compression product, it is well-suited for earthquakes and hurricane areas. Aircrete Europe has developed superior wall systems that range from basements to roofs and all the wall systems in between. This is exciting for Europe but even light masonry products are heavy so shipping to North America is prohibitive. Therefore, for the US, Mexico and Canada, aerblock.com is developing similar systems manufactured in NE Mexico, but thin panels, although in the works and under development, will probably take a few more years into the early 2020’s to perfect.
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Home-made aircrete can be an inexpensive way to build yourself a home (or simply the foundation and floor) by pouring the “foam cement” into forms (usually wooden but stainless steel metal studs that remain attached to the block for extra strength also can work for building slabs. The metal stays with the slab, adding strength, and is not made in replaceable forms).
There are also Styrofoam forms with metal separators (called “Smart Blocks” available at Home Depot) that will increase insulation when filled with cement or aircrete, for building basements and foundations instead of using wooden forms. Build the foundation wall with wood frames or smart blocks and pour in the liquid cement or aircrete. If you used wooden forms, once dry, remove the plywood, but with smart blocks, there is nothing to remove and your foundation wall is complete.
If you are using aircrete to build your slab and/or basement walls, or other structures, you’ll need a paddle mixer for adding water and mixing into the cement and mixing in the foaming agent thoroughly and evenly, being conscious to mix at the bottom of the bucket to get the heaviest materials evenly mixed in. The GaiaDome.com website sells machines that help with making aircrete in their online store to work quicker and more efficiently than just mixing in a bucket and applying an air compressor (90psi/min or better) and a tube, so check out their tools at 2021 prices.
- Little Dragon – $499
- Dragon XL, on sale – $459
- Little Dragon DIY Kit – $359
- Add a foam injector mixer with a Little Dragon – $649
- Add an air compressor, injector mixer and Little Dragon – $1,000+
[Note: Not having gotten my hands dirty with aircrete personally, I have no idea if these are really necessary or not, but they will make the process easier and more time efficient, I am sure. Here’s a video link of how to use a foam injector:
You WILL definitely need a long and strong paddle mixer and an air compressor (90psi/min or better) to make aircrete, as far as I can tell. So there ARE upfront costs (for small jobs consider borrowing or renting an air compressor) plus Portland cement and a foaming agent, such as a commercial foaming agent made by Drexel – Drexel Aircrete FM160 Foam Maker, which does not separate out from the cement like most soaps will, destabilizing your project! (You’ll use 1 oz foaming agent per gal of water and the finished foam should weigh 90-95g per quart. 5gallons makes ~6 cu ft of material.) Getting the mixture right and making forms that work looks tricky (hint: with wood forms be sure to coat the form with vegetable oil so the aircrete doesn’t stick to the forms.)
I recommend taking a workshop if you can, or plan on researching and experimenting before building anything substantial. Build yourself a wall, paving stones, or a shed first so you get experience working with your material and can adjust quantities and slurry texture as needed.
Here are some people who offer hands-on workshops:
- DomeGaia.com has 10-day workshops that build a small dome, teaching how to make forms, allowing you to mass-produce aircrete blocks for building, teaching how to build arches and round windows, how to build a compass arm for building domes, and more. They are offered in places like Tulum, Mexico (easy flight to Cancun with a 2hr bus ride to Tulum, which has cheap travelers’ hostels if there are not onsite options for eating and sleeping), Big Island, Hawaii or in Wildwood, GA (and elsewhere, varying by project) but they sell out quickly so plan ahead and check their website (cost – $700 plus flight and living expenses, I think?).
- Terlingua School of Alternative Building in Texas. Website: https://tinygiantlife.biz phone: 903-231-3808
These 6 to 11 day workshops (at $1250) include building a foam generator, engineering and building with aircrete for your climate, foundation preparation and pouring, plumbing, electric wiring, solar system design, heat load calculations for heating and cooling, plus roofing and other helpful sustainable ideas. They also offer one-on-one hands-on personal classes at $250 per day in Tyler, TX that includes staying in an aircrete structure (the many potential topics are listed at tinygiantlife.biz.) Call 903-231-3808 for personal contact & information.
- Sustainable Living Center in Lincoln City, OR is offering a 6-day Aircrete workshop building a tiny dome home in November 2021. The workshop costs only $200 but you must provide your own sleeping arrangements. One option nearby is a nice hotel with rooms reserved for 9 people at $360 for a single with shared bath and kitchen, or $180 shared room. There’s an RV park 6 miles away at $35/nt for an RV hookup or $23/nt for tent camping with showers or 17 miles away has a place to park an RV or pitch a tent for $15/night, so you will have to work out sleeping details. Register through the website at sustainablelivingcenteroregon.com or call 541-765-2109 (noon to 9pm everyday).
Check online to see if other workshop opportunities exist, as they come and go…
I just discovered a small aircrete house kit one can order but it seems to be a European option so NOT for the US unless you want to pay exorbitant shipping, or it may not even be possible…. It’s called the M2 by Aleksander Kawinski who sends the house in a box to the address provided that is easy to assemble by 2 persons… sounds interesting, especially if you buy 2 of them and put them together in an L shape or add a second floor to expand the space. I haven’t found pricing (I think it’s expensive) or details but since we can’t get them in the USA, I leave it up to you if you want to explore it further. The finished home is an ulta-modern box that you will have to fill with your design elements, appliances, furniture, etc. Something similar may be available in the USA in the future, but for now you’ll probably have to build it yourself!