Have there been any development work with foamcrete?
My understanding is that foamcrete uses less material than concrete, since the aggregate has been replaced with soap bubbles. Maybe it takes the same or more portland cement.
To make a form for a foamcrete dome, use an ecoshell for the outer wall. It probably would not work to just make an entire smaller airform inside, then fill the area in between from the top. Maybe an airform with 1-2 foot tall donut rings, where you inflate just the bottom ring, then pour that, before inflating the next ring. That way you have access to the full circumference in 1-2 foot lifts. This makes the inner airform and inflation support much more complex, and probably 3x the material, but hopefully it is completely reusable. Possibly the lower ring could be inflated with water instead of air, to help anchor it to the floor.
We have not. There are a few reasons why we’re not super excited about it.
We tried out a TON of alternative insulation methods, and none of them worked very well. Interestingly enough, the data showed that a good reflective coating was more effective at controlling heat than any other foam concrete could. The lime wash, done the right way, was by far the best with the Texas heat.
We build FEMA rated buildings. We need the high strength concrete to do that. Foamcrete doesn’t offer that (today).
We also have to do what’s economically feasible, as we are out building domes every day. There are some alternatives, but they are time consuming and often complicated to put into real production.
That said, I hope I am not discouraging you or others from experimenting more with this stuff. The tests we did were not fruitful, but they were very fun, and we are using those buildings today! So, it can be done.
Now let’s discuss dual membrane domes. I have actually spent some time on this, and I think I have it figured out finally. I haven’t tested it yet, but its more complex than people think.
There is no way water will hold this airform down. Trust me. I have inflated a few domes before. You are going to need a concrete footing, and it will need to be substantial enough to hold down the airform.
The tests we’ve done are very minimal, but I hope to do more someday. The next one I do will target a full pour in one shot, and it will probably not be a “foam” mix, but it could have some ceramic beads in it to keep it light.
The Airform will be the most technical part. I may keep that piece close to the chest for now, but this conversation is making me want to get out there and try it again…..