Transcription
Aeroccrete is amazing, but making it usually requires an expensive foam machine, an air compressor, cement mixer, and meticulous trial and error to learn how to use everything correctly. But it doesn't have to be that difficult.
In this video, we'll learn how to make Aeroccrete that is lightweight, fireproof, more insulating than foam board, and so easy to make. A bag of cement and a few items from the local grocery store is all it takes. My name is Ben. Thank you for being here.
This is a block of Aeroccrete. An ordinary cinder block of this size weighs almost 40 lb, but this one is more than 60% air. It is incredibly insulating, like the world's best styrofoam. Minus the microplastics, it's completely fireproof. It blocks sound like almost nothing else, all while using less than half of the raw materials of concrete. And it still cures basically into solid rock that can last for centuries.
Materials with incredible properties like Aeroccrete are often made by experts, people who have spent endless hours researching a topic and building custom tools to make the best version of that thing. As a result, the recipes and methods these experts come up with seem simple to them. But for those of us who just want to try a new thing and have it work the first time, that usually requires a new approach.
When it comes to airrated cement, the expert method is to use a DIY or purchased foam generator calibrated with a custom detergent mixture to produce foam of a very particular density. Followed by mixing the perfect amount of foam with the perfect amount of pre-wetted cement, which is stirred just enough, but not too much before the Aeroccrete is ready to pour. Get any step wrong and the batch will fail.
Thankfully, you can get results like this with no expertise. And I made it my business over the last few months to discover how. Unlike the expert method, my process does not require any specialty tools to generate foam. By simply mixing the cement, even by hand, bubbles are generated automatically, which is typically an impossible thing to pull off. Because cement is heavy and extremely alkaline, it actively destroys the bubble forming ability of many detergents while also pulling the water out of foam as soon as it's added. It's a race against time to mix foam into cement before it collapses. Generating foam directly in the hostile environment of wet cement is a pipe dream according to conventional methods.
But the secret that I have found to make this work is zanthan gum. This is a thickener that you can purchase at almost all grocery stores. It's much cheaper to buy it in bulk online, but I very much like when cutting edge tech can be pulled off with grocery store items. It's more fun that way. If you mix zanthan gum directly into cement, it will do almost nothing. The cement steals all of the water immediately with none left over for the zanthan to do its thing. That changes if you combine the zanthan gum with water first.
So, here is my recipe. This is a two-step process. First, we create a mixture of zanthan gum detergent and water. And in part two, we mix this with dry cement. Make sure to wear a mask while the cement is dry and throwing off dust.
We start with 15 g of zanthan gum in a large container. And to this, we add a splash of rubbing alcohol. Even alcohol-based mouthwash will work for this part. And you don't have to be precise on the quantity. The purpose of the alcohol is just to create a slurry with the zanthan gum and pre-wet it. Without this step, you will have a really difficult time trying to mix the zanthan into water directly without it forming clumps.
Next, we need 60 ml or a/4 cup of dishwashing detergent. This is Dawn Ultra detergent. And if you use a different brand, just make sure that the top ingredients are the same ones that are listed on screen. Now, once the dish soap is stirred in, we can add one liter of water to this container. And that's all there is to it. This solution should be left to sit for 5 or 10 minutes for the zanthan gum to fully hydrate and thicken up, at which point it will be a very thick gel. By prehydrating this mixture, the zanthan gum will slow the cement's absorption of water, which preserves the thickening effect and also protects the foaming power of the detergent.
There is only one more step to turn this into a to mix it with cement. For real, that's it. Measured by volume, you take one part of this gel to two parts of Portland cement and mix them together. Any sort of mixing method can be used here. Even a spatula or a paint stick is adequate, but it's less work if you use something like this. It will seem at first like there's not enough water in the cement, but with continued mixing, it quickly becomes more liquid as bubbles form inside.
One of my favorite things about Aeroccrete is that it's so much easier to stir than ordinary concrete. Both because it's lighter weight and it's much softer. It's just a pleasure to work with compared to the struggle of stirring concrete in a wheelbarrow. The more you stir this mixture, the softer and lighter it becomes as it slowly expands to fill more of the container. And this is the only variable you need to worry about. The more you stir, the more the Aeroccrete will expand, giving you a lower density product in the end.
If you want a version with more mechanical strength, quit stirring when it is only expanded a small amount. If you want lighter weight and more insulative value, stir longer until the foam expands fully. The easy way to get consistent results is to draw marks on your container so that when you start another batch with the same amount of ingredients, you'll know exactly when to stop stirring once the foam reaches that line. Doing this will make a with exactly the same properties as previous batches.
Eventually, if you keep expanding the foam for long enough, it will start to separate from the cement. This becomes obvious if you stop mixing and notice that the bubbles at the surface pop. This is the transition point between making Aeroccrete that has a closed cell structure to now making an open cell version. Place a mark on your mixing container to indicate that this is the limit for making closed cell aerocete. Continuing to mix past this point can still be very useful for particular applications. Open cell foam is more fragile. However, the open cell structure left behind by the popping bubbles allows liquid to pass through it. The obvious use that comes to mind is making DIY filtration systems. Potentially, you could also make blocks that are both insulating and breathable.
So, let's do a test of Aerocrete's insulation value. This is a sample that has been whipped with about 60% air, which is a good balance between insulation and strength. We could push the air content way higher, but I think this will be enough to get the point across. I've poured this into a hollow in a piece of foam board with a known insulation rating of R6. So, we'll see how the Aeroccrete compares.
So, this goes on top of a cooler with a 40 W incandescent light bulb inside to act as a heater. I've covered the bulb with foil so the samples are not getting warmed by direct light, just the air temperature inside. I'll also insert a temperature probe on the underside of the panel which will help us to measure the difference between the inside and outside surface. A piece of electrical tape across both samples will give us a consistent medium to take an accurate thermal measurement. And lastly, I'll cover this with another sheet of foam to stabilize the external environment.
After an hour, we can take a look with a thermal camera. Notice how quickly the foam cools off, but don't let that fool you. The electrical tape held its temperature long enough to get a reading of 94.5° F on the foam compared to a reading of 92.4° on the cement. The Aeroccrete is indeed allowing less heat through it than an R six foam board of the same thickness. And this sample isn't even as airrated as it could be with a temp reading on the inside of the panel of 138° F. And using the known R six rating of the foam as a baseline, I think I calculated correctly to say that the R value of this 1-inch thick sample of Aeroccrete is 6.3 better than foam. I think I gave this test my best shot, but I'm not entirely confident that it's a good setup. Leave me a comment if you know of a better way to measure our values with simple tools.
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Well, one of the things that I have not yet discovered is if this method for making aircrete will actually work inside an ordinary cement mixer. These rotate pretty slowly and up until now I've been relying on techniques that really whip that cement up much faster than cement would normally be mixed. I think that there are probably other methods that could be used to make this on large scales if this does not work like modifying a cement mixer to rotate more quickly. Uh maybe premixing the foam a little bit so that it's a little bit easier to get it started. There's other things we can do, but if this works as it is with no modification, then we're on to a method to make aircrete that could be made at scale incredibly easily. We just got to try it and find out.
So, for my first test here, I will be making a 3gon quantity of aircrete. Starting with one gallon of water uh pre-thickened with 60 g or one heaping/4 cup of zanthan gum in my bucket. And I will make a slurry with this using alcohol and then one cup of dishwashing liquid. So one cup of dishwashing liquid. This is a half cup measuring cup for every one gallon of uh the base mix for the aircrete. All right, we got our zanthan slurry made with our one cup of dish soap. Now I'll just fill this bucket up to the onegon line and allow that zanthan gum to hydrate. Pretty thick at this point. I'll throw this in here. It's kind of hard to get it all out of the bucket because it's so thick. I have barn spatulas for this very reason. Why am I scraping it out with a glove? All right, let's now add two more gallons. We'll measure by volume of the uh Portland cement into this mixer and get it going. Boy, I'm excited to see if this works. All right, see if this secondhand mixer works. All right, bucket one. Here's bucket two. You can see how crumbly that starts out. It really doesn't look like enough water, but it really is. I'll stop this for a second. I want to see if uh I want to see if the liquid is coming free of the drum properly. It's kind of a that's a very small batch of of cement for a mixer this big. So, if one of the problems might be that it's just uh not quite enough cement for this mixer to work properly. My goodness, it's working. Kind of like bread dough. Oh, if anything, the mixer might be going too fast for the cement to fall now that it's it's not as heavy as it was. I can take the mask off now that there's no more dust. But I think that in order to make this work properly, I might have to hold the drum like this so that uh there's the gravity is pulling it that cement off the back wall a little faster. Doesn't look half bad already. I thought it would take longer than this. How is our texture? I mean, it is pretty light and foamy. Gosh, did it stop mixing? Because it was already becoming starting to get to the point of being overwhipped. I mean, that was in there for like 3 minutes, less than five. We might already be to the point of a good Aeroccrete mix. I have my uh a little cinder block mold here. We'll pour it into this and see. Uh gosh, I guess see what it looks like. I mean, it is definitely airrated. It uh you know, it stands up like a stiff mering. Oh gosh. Well, that didn't work. Yeah. I mean, that is a super lightweight mix, but it is surely airrated cement. I figure that by how much cement it just took to fill this mold, um I think the volume has probably expanded about half as much as the aircrete that I made earlier using a hand mixer. So I think that is the trade-off here. Using a proper cement mixer like this, I think you just end up with a little bit less foam density um and a little bit higher cement density. So, this uh is maybe a mixture with about 50% air in it instead of um like 75% which I got with the hand mixer. It's still a pretty lightweight brick, though.
So, here's the block I poured from the cement mixer. I struggled to get this to mix properly after it reached a certain level of foam because it just got too dang light. it wouldn't fall to the bottom of the mixer. It could be that this would have worked better if I had filled the mixer to a more normal level. Two or three gallons of cement is a pretty small quantity for a mixer of that size. But in any case, this block is certainly more than 50% air. It should weigh 50 lb. It actually weighs 22, less than half. So this is viable aerocetrete on the denser side, but it was made with only a cement mixer, which means that this method is viable at large scales with standard building equipment that anyone who already pours concrete would know how to use. That is a huge deal.
Another option for medium-siz projects that can easily achieve the highest foam density is a paddle mixer and a drill. I used this miniixer to make the Aeroccrete for this block in a 5gallon bucket. I'll show you how I did that so you can see another example of how to actually mix this stuff practically. I'll try not to kick up too much dust as we do this. Kind of inevitable. Yeah, you don't want to breathe that. All right, here we go. So now it's already starting to lighten up. You can see that it's actually soft at this point. Look at that beautiful texture. My goodness, it is so lightweight. It's like liquid styrofoam. Amazing. All right, let's pour this into a mold. Yeah, not quite enough to fill the mold, but I could have actually whipped quite a bit more air into that if I wanted to. That would make the block weaker, of course. Um, but I think that this will be adequate for this test. Very good.
The cure time for Aeroccrete is the same as ordinary concrete or cement. It takes about a week to reach 75% strength at room temperature. The one thing to be aware of is that Aerocrete dries out much more easily than standard cement and it will not cure properly if it dries out in the first few days. You need to cover it with plastic or cloth that is kept damp for at least four or 5 days while it cures. But that is all there is to it to make this pourable fireproof insulation in a way that works every time. So add that to the list of new inventions we've come up with right here. Easy mix AOcrete. You can help support me on Patreon if you find this sort of information valuable. We do stuff like this all the time and you can check out everything that's been done previously by looking through the past videos on this channel. Leave me some comments below, please. I love hearing from you. I'm Ben. Thank you so much for watching. I'll see you next time.