I'm interested in doing some projects with AirCrete. I've been looking at various building blocks even that are built out of foam concrete such as the following blocks:
The problem I'm having is how do you come up with the recipe? The litebuilt people create these blocks in two types. One is a density of 600 kg/m3, generally used for insulating purposes or interior walls that aren't load bearing. Then the other is a density of 1100 kg/m3, used for outer walls and load bearing walls.
When looking into the recipe described by DomeGaia I finally found that the process of 94# of cement + 7 gallons of water + 36 gallons of foam equates to a foam that is about 300 kg/m3?
Is that right? 19 lbs/cubic foot? That's not hardly worth much in terms of strength. Are my hopes and dreams destroyed? Or am I wrong about the density? Or can you increase the density? I notice they do as much as a 3:1 sand ratio, or at the minimum a 2:1 sand ratio to achieve the 1100 kg/cubic meter or 69 lbs/cubic foot density rating. Not sure how that measures out with the foam also.
I'd very much like to work with this foam concrete to see its potential but I'm leery to try it as any kind of building material like I hoped for now that I can see it's expected density. Any help or better understanding of the possibilities would be much appreciated.
Don't worry your hopes and dreams are still alive. You can change the density two ways The first is to add sand to your cement that will make your aircrete stronger. The second is by changing the amount of foam you use. By using less foam you make your aircrete density heavier. You can get an idea of density on this chart. As you know the denser you make your aircrete the less insulative it will be.
Thanks Talyn, this is very helpful. I had found the mention calculator, but it deals with very large quantities and uses terminology I didn't quite understand. This helps a bit more, as well as renewing my hope as you said.
I have a couple more questions:
How do you test the density? I'd like to better understand how to test it so that if I mix and work on a few recipes for my use I can test for the actual density I'm achieving, but I'm not finding a lot on how to test.
Are there any recipes to work from beside the favorite recipes already shared on this site which achieves high insulating but very low strength? I'll try to work on this calculator a bit more to understand it better, but would love to see some smaller volume recipes shared as well.
First thing I do with my Dragon is set the water pump to maximum flow for the foam solution. Than air pressure is set to 90 psi. Than I take a 5 gallon bucket fill to the top with foam and weight it. What you want is 3 or more pounds of foam. Make sure to zero out your scale for the weight of the bucket first. You should always use this foam density for making aircrete.
As for recipes the only one I know of is in the calculator I posted before. Otherwise I would say do your own testing of different cement to sand ratios to see what works best for your building blocks.
Here are some videos I made I hope this helps you.
Very interesting. I've been playing with the calculator more now that I understand it better. It's interesting to see how the values work out. Plugging in the values of the "favorite recipe" here for insulation properties, I'm getting an expected density of about 24 lbs/cubic foot. And it was reported in one forum post to be about 19 lbs/cubic foot. So that could be pretty accurate depending on the foam used.
This is a pretty handy calculator to build some basic recipes off of, but naturally need to pour and test for exact numbers. This has been very helpful.
The number I get bases a 5 gallon bucket at a size of about .78 or .8 cubic feet, so if you want that to weight 3 pounds for your foam, you generally try to get 3.75 - 4 pounds per cubic foot for your foam density? Is that about correct? Or is my math off? Just trying to get a bit specific as I plan to build with this and exact formulas are important for repetition.
Yes that is right!