Vermiculite concrete under brick arch Getting Started Discuss Vermiculite concrete under brick arch in the Pizza Oven Design and Installation forums; Hi everyone, Quick question- I have built my oven base on a thick slab and then made a 12cm slab ...

[greykitty]

Hi everyone,
Quick question- I have built my oven base on a thick slab and then made a 12cm slab on top of the base bricks, I would like to add a concrete vermiculite mix on top of that slab/underneath my oven floor for heat retention... here the question: will the vermiculite concrete be strong enough to hold the brick arch and floor tiles? I had a look at vermiculite yesterday and it seems very light... Do I have to put another layer of concrete on top for stability? Thanks for your help…

[james]

Hello,

I moved this to Getting Started, so you can get more input. The short answer is Yes.

Vermiculite is pretty odd stuff (it's basically volcanic popcorn), and it does seem light and not very stable, but is will set and become solid and it has very, very good compression strength. Your oven will be solid!
James

[greykitty]

Thanks James -I will give it a try this weekend.

[dmun]

It dries to a cork like consistency. It will flake off at the edges, but you mostly want to keep the edges covered anyway.

In short: Vermiculite concrete has lots of compressive strength, but almost no tensile strength. It's used for swimming pools that are under tons of pressure.