! 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...