Perfect + easy building material: Aircrete 2.0

Ben (NightHawkInLight) has done it again folks!!! This is truly amazing - he has made it possible to make aircrete without any significant tools and it is easy to control the structural vs thermal attributes of it. This may be the PERFECT building material... with just changing the process up by using a tiny bit of xanthan gum, alcohol and soap!

I have watched the video. It is nice, but after analyzing it, it is very expensive. For fun I have calculated cost per block.

Portland cement $4.56 (HD)
natural detergent $2.72 (Walmart)
xantan gum $2.04 (Walmart)
which totals to $9.32 per block (looks like it's lower than standard 8").
Labor to make the forms and the blocks is not included.

The cost of Faswall ICF block would be $12.3 (with average delivery cost) per equivalent of 8x16x8 block. Both would need rebars and grouting, but the aircrete block would have probably less insulating value than Faswall, because of thinner walls and lacking the insulation insert. I picked Faswall, because it has no plastics or nasty styrofoam.
If buying materials in large quantities, maybe, but only maybe, the price could be reduced to $5.
Using not natural detergent would drop the price too, but why to put so much effort and have dyes, synthetic fragrances and allergenic chemicals in the wall of own house?

For comparison in Europe, the same size Ytong (AAC) block (solid) costs $1.6 and insulating clay block $1.8.

Let's check how it compares for plaster. It could be useful as insulating plaster if applied thickly 25mm/1". For covering 1m2 it would need equivalent of 2.2 blocks so $20.5/m2.
For comparison lime plaster (not insulating) made from high calcium lime and sand would cost $4/m2 or less if sand was bought by a truckload.

One bag of cement, one bottle of detergent and the bag of xanth gum makes a lot more than one block.
The other blocks you mention are not available locally for me.

I don't think I would use it as mortar, but using it as filler in a conventional block or even a stud wall is very appealing.
Using it as  insulation behind  a hard firebrick  hot face also seems promising.

I fear even the closed cell version would soak up too much water to be a good outdoor wall cladding, but it were sealed, maybe it would work.

This idea is fascinating to me on many levels. Yet more questions remain, perhaps more than answers, indeed.
Portland 94 lb bag costs about 20 clams for me, hurting my wallet as much as the shoulder I use to carry the damn thing.  It is nice to have options by buying this, adjusting ratios to sand in myriad circumstances.  So the number posted here must estimate the amount used for a block, I am guessing. So is that about 9 blocks crafted per bag of Portland? The total price per aircrete block still seems cost prohibitive

But the basic idea, adding insulation via air pockets in a block, is an important advance.  How best can this be achieved?
This is another example of my basic incredulity about our capitalist system, which proclaims to have open competition....but then how do we square the idea that a project I buy block for in the EU has amazing choice available for block? And the USA has very little affordable choice ,ready made ,for the exact same project?  Those insulating clay based block in Europe are amazing to use, effective and affordable, full stop.  And if one percent of the red clay in GA was dug up, I bet we could have the same product for sale here.
Could anyone share their experience on this topic? I hear William  , and have a hard time comprehending "how we got here"

A full bag mix is enough to make a 2-3 inch thick 4x8 sheet of insulation. Pink insulation board is currently $60 for a 2” slab.

So aircrete might not be cheap, but it is cheaper than other options right now.

Going from his recipe of 4 liters of dry Portland powder per block, I get 7 per 94 lb bag.
The bags are 17 dollars where I live, but going with $20 per bag that's a base cost of $2.86.
If you used an entire bottle of dishwashing liquid and an entire bag of of xanth gum for each block, you would still only spend an additional $4.76

Im just gonna round up to $4 per block.
That's way more than I pay for conventional block, but conventional block has no insulation value to speak of.
It still makes little sense to use this material to build a block wall.
Where are you going to need a structural element that isn't lab tested?
Even if you are building without permits,  $4 dollars per block plus the labor involved is a lot.
Better to use it as a pest proof pour in insulation in an already self supporting structure.
It would add lots of strength, but you wouldn't be relying on it for that.

If I were making custom blocks anyway, then I would find it worthwhile.
A trapezoidal dome built of custom aircrete blocks, that  makes sense to me.

William, he used two gallons (7.6 l) of cement to make a block. My calculations in the previous post are for one block not for a bag of Portland.

I think the diiscussion revolves around foamy (insulating and cheaper) aircrete made by paddle mixing, but with a prospect of making it quickly in bulk in a mixer.

According to this recipe made IN THE MIXER a bag of portland cement will make only 0.87 m2 of 5 cm thick insulation, so it would be 9.3 sq ft of 2" thickness. Maybe other methods of foaming will produce much more, but not this one made in concrete mixer that basically converted 2 parts of cement to only ca 3 parts of mix.
Also, the test sample was made with a kitchen mixer (and used for measuring R value) and the block - in a concrete mixer, resulting in a very expensive (and different) product.
Mixing with a mortar paddle would result in much better foaming, the cost would drop significantly, but at the same time it would slow the production to build something bigger. I just liked the method of bulk mixing in an ubiquitous concrete mixer.

I would not recommend wasting insulating material in a regular CMU block cavities. Due to massive thermal bridging, the R value of a 8" block wall filled with PU foam increased from R2.0 to only 3.7. Block cavities were designed for reinforcing. Block wall needs continous rigid insulation on the outside or 2 wythe wall with insulation of choice in between.

I'm not against aerated concrete - just the opposite. I wish AAC blocks were available in every construction big box store as the cheapest quality building material available, allowing to (easily due to light weight) build bearing, insulating, breathing, fire/pest proof one wythe walls. CMUs are so 60s, when nobody cared about any insulation.

Rico, US and Canada are traditionally non masonry countries, so we have to resort to laborious DIY or use deeper pockets to purchase/import.

Thank you both for the help, as usual my math was off base. And RScott, you are right on target about relative pricing.  Also good, Cristobal, to realize the mechanics involved mean a great deal to finished product, eg, air pockets and R value in an expedient concrete mixer.

I apologize to anyone I have offended by posting my opinions,  that was not my intent.  Somehow I can no longer upvote replies by others, sorry for my replies that are unworthy or wrong, I have zero social media experience so please accept my apologies.  Simply trying my best to follow the rules, folks
Rico

Sounds like the difference is how much air there is in the mix.
He does say the drill mixed recipe did not totally fill the form, but suggested adding more air.

The block that came from the concrete mixer weighed  22 lbs.
Working from that, and 20 dollars a bag, I get almost the same cost for cement that you did.
Like any kind of concrete, the ratio of aggregate to cement is key to the cost of a building unit.

I would like to know how long the soap and xanthan mixture remains stable.

You make great point about filling the blocks not helping insulation values because or thermal bridging.
If anything ,aircrete bricks filled with concrete makes more sense.
Using aircrete as an infill for stud or post and beam structures makes sense to me.
Using it as an insulating parge might work, but I'm not sure how it would affect where condensation might form.

William Bronson wrote: One bag of cement, one bottle of detergent and the bag of xanth gum makes a lot more than one block.
The other blocks you mention are not available locally for me.

I don't think I would use it as mortar, but using it as filler in a conventional block or even a stud wall is very appealing.
Using it as  insulation behind  a hard firebrick  hot face also seems promising.

I fear even the closed cell version would soak up too much water to be a good outdoor wall cladding, but it were sealed, maybe it would work.

What got my interest was the testing against foam board......            some ideas come to mind.

1)   how about we modify the rocket  pizza oven to air create  from fiberglass....    

2)   what about building an ice house  with this as the insulation .....

3)    What if this was the outer layer on cobb oven?   The insulation should hold heat nicely....

4)    Sand battery,    use this to hold heat.....


I have already built a foam generator.....     so I don't see the great advantage of using the  xanthum gum   instead of building the foam generator...   Yes you don't have to generate the foam, but on the other hand you are paying for the Xanthum gum,  which i have found it pretty expensive at least where I buy it.

I am wondering  can this replace rockwool....

I have already chopped up lots of styro foam....      I think it would be interesting to build boxes  one made with this mixture and compare it to regular air crete to see if one has better insulative values than the other...

I am thinking build   a 6 inch box mould,   then put in a  cup of ice and see which one melts first..

Truly great discussion,  makes me engage with further research

Is the fiberglass you references supplanting mixed in for crack resistance or separate as a layer for of insulation?

I wonder if guar gum, psyllium husk, or ground flax/chia seeds could substitute for  xanthan.

Aerated concrete blocks use aggregate (and lime) like normal concrete, otherwise they would be too expensive, even in Europe where cement is on average two times cheaper.
For reference, here are Ytong block parameters:
300 kg/m3 lambda=0.072 (R1.9/inch)
400 kg/m3 l=0.105 (R1.3/inch)
600 kg/m3 l=0.17 (R0.8/inch)

To achieve reasonable R10 of an 8 inch wall, the specific gravity (ro) of the mix would have to reach 0.4
According to my measurements, Portland cement out of the bag has  ro=1.5. It means the mix would have to increase its volume almost 4 times. For comparison, the mix in the concrete mixer changed from 2 gallons to 3 - only 1.5 times.
In case of using aggregates, initial specific gravity of a sand and cement will be at least 2, so its volume would have to increase 5 times to get R1.3/inch.

The conclusion is: proper foaming is the key, otherwise it's wasting of materials.

Mart Hale wrote:3)    What if this was the outer layer on cobb oven?   The insulation should hold heat nicely

It would hold it nicely, but since it's difficult to make, oven builders use perlite (or expanded clay aggregate) concrete. 1:10 cement to perlite may result in ro=0.3, lambda=0.07 mix. For comparison insulating firebrick IFB2300 has ro=0.55 and lambda=0.17. Higher temperature rated IFBs have higher densities and lambdas. I have used such concrete to insulate the floor of my bread oven and also to insulate the roof of coop/barn. 1:10 is crumbly, but perfect for flat insulation. For walls it woul be better to use 2:10 mix.

Mart, it would be nice if you used your foam generator to measure what volume increase you can achieve with various mixes.

Rockwool lambda is around 0.035, so still 2 times better than 300 kg/m3 Ytong, which has compressive strength of only 2.2 MPa (319 psi - bottom value for CEB blocks). If it was foamed even more it would become too delicate for self supporting, but good as infill or flat insulation.

It's an interesting topic, but I think the light clay has more potential for average builder: cheaper, healthier, very easy to make, tried for few thousand years. Aerated concrete blocks is the territory where technology and ecenomy of scale shine. When the blocks can be purchased cheaply in most stores and various shapes then it beats the clay (for overwhelming majority of consumers), because they get ready and widely known product that allows to build the walls very quickly. They claim that a team of 3 can build 40 m2 of walls in 8 hours.
For comparison my mason and me as the helper did max 4 m2 of CEB wall in a day.

William Bronson wrote: Is the fiberglass you references supplanting mixed in for crack resistance or separate as a layer for of insulation?

I wonder if guar gum, psyllium husk, or ground flax/chia seeds could substitute for  xanthan.

I was thinking the insulation between inner and outer barrels....      I would guess it would depend on how hot one fires the rocket oven as the heat would crack the aircreate...     Fiberglass is good up to about 1000 deg and would be lighter and no cracking...      But always fun to think about possibilities...

NightHawkInLight’s thixotropic xanthan + Dawn + alcohol gel is the key that lets the foam hold after the bubbles pop. Traditional aircrete collapses at that point. The gel keeps the shape, so you end up with a true open-cell, fully interconnected porous concrete instead of closed cells.

Once you have open cells you can do the rest of the cascade:

• paint black or load activated carbon → near-total solar absorption  
• phi-spiral air path → stack-effect vortex, massive surface-area exchange  
• copper coil in insulated ferrocement tank → store the heat  
• parallel wet open-cell trench + desiccant → latent-heat evaporative cooling to \~35-40 °F even in high ambient  
• Stirling + flywheel + TEG on the ΔT → mechanical + electrical without grid  

All of it is already documented, physics-checked, and stamped open-source (CC-BY-SA docs / GPL-3 code) at:

https://github.com/jesseray718/openroot

I’m in southeast Missouri and will build the first full system as soon as I have a site. Looking for people who want to run the numbers, critique the mixes, or help prototype. Happy to share every measurement in joules.

Xanthan Gum IS EDIBLE, BUT, BY WHAT??? I would like to know the answer before getting into production, probably come up with more concerns.......
[size=12] [/size  not much testing done

I believe this is consumed by way of some ice cream in 🇺🇸
and Little Debby products like the artery-clogging Swiss Cake Rolls, Honey Buns

There is an update (youtube post not a video) apparently sand can be added without losing much properties. New ratio is 4 sand, 2 cement, 1 bubble mix. Previous price calculations are substantially reduced now. Link here:
https://www.youtube.com/post/UgkxuwoLOQKrCspMb__O4fJ2TUhPQCEeY-46

I'm very tempted to make a partition wall of aircrete  2.0. Has anyone tried making anything like that with aircrete (foam or any other diy method)?

Has anybody actually tried reproducing the technique from the video?

I tried it twice, and the mix wouldn't aerate much. I got maybe a 30-70% increase in volume, not the 6x often mentioned by other aircrete Youtubers. I used a heavy duty drill with mixer paddle attachment.

This is my first time making aircrete so i don't know if I did something wrong, but this technique did not appear to work at first glance, or at least it's not simple to reproduce just from this video.

M Pearson wrote:Has anybody actually tried reproducing the technique from the video?

I tried it twice, and the mix wouldn't aerate much. I got maybe a 30-70% increase in volume, not the 6x often mentioned by other aircrete Youtubers. I used a heavy duty drill with mixer paddle attachment.

This is my first time making aircrete so i don't know if I did something wrong, but this technique did not appear to work at first glance, or at least it's not simple to reproduce just from this video.

From what I've researched 30-70% is about right. not sure where you get that 6x from. Again from the videos I've seen beyond 50-60% air apparently is the limit to closed cell (unless you want open cell for filtration purposes like in nighthawkinlight video)

Sorry I don't have personal experience to share. I still haven't gotten hold of xantham gum and other tools and materials. I'm leaning towards just ordering stuff and learning from failure in the worst case scenario but I am slow and will surely take my time even for that.

All the other aircrete people on Youtube seem to be suggesting their aircrete mix grows by 6 fold or so when using the foaming gun. For example Tiny Giant Life, Domegaia, Honey Do Carpenter..
Check for example this Domegaia video around 6 minutes: https://www.youtube.com/watch?v=tnNua21zx78

They go from a barely full barrel of 1 bag of portland cement to a nearly full barrel after adding the foam & mixing. The consistency i also completely different from mine, much more liquid and soupy than what I got, which was essentially the same consistency as cement.

Walmart has Xantham gum in the baking aisle.

On domegaia website, mixer and foam generator can be purchased for $900. Let's add a $300 compressor.
The video of soap/gum/cement mixing produced a 8x8x16 (actually lower than 8") block at $9.3 with foaming factor of 1.5. After 170 blocks it breaks even and the tools are "paid". 170 blocks would build 19x8' wall. Soap/gum blocks would be hardly insulative and very non permie, because a lot of cement and chemicals would be wasted. It's presented as a cheap method... to produce very expensive and hardly insulating blocks, because in AAC at least 400% volume increase is the objective, not 50%. Using domegaia tools an 8x8x16 block would cost ca. $2 in materials, but could go lower if cheaper cement was sourced. Regular concrete block currently cost $3 in many locations and $3.5 where I live.

M Pearson wrote:All the other aircrete people on Youtube seem to be suggesting their aircrete mix grows by 6 fold or so when using the foaming gun. For example Tiny Giant Life, Domegaia, Honey Do Carpenter..
Check for example this Domegaia video around 6 minutes: https://www.youtube.com/watch?v=tnNua21zx78

They go from a barely full barrel of 1 bag of portland cement to a nearly full barrel after adding the foam & mixing. The consistency i also completely different from mine, much more liquid and soupy than what I got, which was essentially the same consistency as cement.

Walmart has Xantham gum in the baking aisle.

Apologies. I had only skimmed through those youtubers. I had seen "manos de tijera" from colombia. His mixes seem to be about 2-3x volume, and for reference his recommendation is: wet mix should be 90% of water weight and 80% of water weight when cured. This was more or less consistent with nighthawkinlight. His resulting block seems quite strong. I mistakenly assumed that was the breaking point in his experiments and more air would make a too dusty or prone-to-cracks block

I suppose we have different intentions. you guys want minimum material cost and scalable production (possibly as an insulation filling?). I want ease of fabrication and a stronger block and I benefit from cheap local concrete .  Aircrete is weaker than concrete. From what I've seen domegaia is okay with that because of the structural integrity of the igloo shape plus the size of their block, honey do carpenter blocks seem to use reinforced mesh and from what I can tell all structural support comes from wood/metal scaffolding)

When researching aircrete (or anything really) I look for failure reasons, this video specially:
https://www.youtube.com/watch?v=Ogf2hIboyFI
made me realize the DIY fabrication process is very delicate, the right density of foam, with the right amount of mixing, during the right amount of time all with very precise ratios of material. otherwise you get cracking, or a block that slowly becomes "powder".

The xantham gum recipe is attractive to me because of theoretically more consistent results and no extra tools (those foamers are expensive and even more so here). I live in Peru so no walmart for me but I intent to buy a whole kilogram of xantham gum from a chemical supplier. today I learned that the "portland" we manufacture is different from that in the US apparently we replace clinker with naturally abundant local stone so concrete is very cheap here, lucky me on that regard but I will need to experiment to see how that changes results. I guess that also makes local portland much less energy intensive and manufacturing is nearby so little transportation footprint. I was ignorant the situation was so different in the states, I stand corrected.

@those who are running numbers if you can replace 2/3 of the portland for sand, and buy xantham by pound/kilogram the material I guesstimate new cost should be maybe 1/3 of what was previously shared in this thread. right? maybe I'm wrong of course. My situation is unique in this forum so I'll have to see what happens. I'm just glad to have promising  options

Replacing part of cement with some fine aggregate would be great, but it would have to be really fine - as I can not imagine that some home mixing would be able to "lift" sand particles. Small bubble can easily support cement powder (or flour in egg whites foam), but if we imagine replacing it with sand or for better picturing coarse sand - the weight of aggregate particles will exceed the holding capacity of a small bubble.
I think that silica mesh at least 150 or finer could work. Please try and share the results.
I use silica 325 for making custom glazes for my ceramics. It's powdery like cement but also 4 times more expensive.
How much do you pay for 50 kg of grey cement?

last I checked a 42KG bag of cement here was a bit under 7usd. I think there are cheaper new brands/bulk discounts. what is holding me back from trying something is locally I can't source those plastic concrete block moulds. I'll have to make my own out of wood or something (and I don't have wood tools). also I still haven't ordered xantham gum. You make a good point about weight of sand. Maybe that's why the south american youtubers only go about twice volume with mixing aircrete. I will get to it and share my results for those curious but the material cost and particularities of local cement will probably make anything I share non reproducible for you guys

Mike,

One advice. Try to avoid regular wood for forms. I was using dried wood planks, that I planed and  made forms for clay/perlie bricks that I fire afterwards. After few hours the forms bowed badly from moisture before the bricks dried. Next time I will have to line them with something or use different material.