Mixing Insulating Concrete

[dmun]

Re: Mixing Insulating Concrete

Just to clairify Leemc's post: Using a blanket covered by vermiculite is not good between the floor and support slab. That's a pretty standard finish over the dome if you're doing the igloo style.

Lildave

I think using a blanket under the perlite is a bad idea. It will probably compress loosing a lot of its insulation value and likely cause a structural failure of the oven above it. Better to stick with perlite or FB board if the thickness is a concern.

You could use a blanket on the sides though with perlite over it. That's what I did in my oven - you just don't want weight bearing on it.

[Neil2]

Re: Mixing Insulating Concrete

Using my concrete mixer, I found the vermiculite particles were breaking down, producing a denser = less insulating material. I eventually mixed it gently in a wheel barrow. I used 5:1 for under the hearth and 12:1 for the dome insulation layer.

[KasinH]

Re: Mixing Insulating Concrete

I'm wondering if someone could put, say, crushed stone, rocks, seashells, etc. over that perlite/cement finish you're showing in the first picture instead of the bricks you're showing in the second picture?

KasinH.

I covered my whole dome with it and it worked fine for me. Started at the bottom and built it up in a thick layer. I did have an initial layer of used firebricks which I'm sure helped as it gave me a terraced effect. I did add a small amount of fireclay which I believe improved the workability. I cut some of the layer off with a handsaw for my entrance and it was a lot like styrofoam, fragile but it floated too! I had a very high perliteortland ratio.