Some design questions on Pompeii oven

[Justin]

Hi, i have decided to take the plunge and build one of these Pompeii Brick ovens!!

So far i have dug a space for a slab and boxed it up, it is 3m x 2m x 0.14m, i plan to have a 1m landing at the front (see diagram)

My most immediate design question is whether an opening of over 1m in the block support stand will be too large and may not be strong enough to hold the the weight of the oven. I'm planing on just using angled steel as a lintel to bridge the gap.

My second design query is: is it possible to build the dome from refractory concrete, ie will it hold enough heat and work ok as an oven.

Thanks in advance for anyone that can help me

[Justin]

Re: Some design questions on Pompeii oven

I have updated my design overnight, i think this sized opening is much more practical.

[Frances]

Re: Some design questions on Pompeii oven

... not necessarily. The bigger opening would make it easier to get wood in and out of the storage space, and if you put and extra amount of rebar over the doorway when you pour the concrete slab it will hold up fine. In fact my opening is exactly 1m wide

But if you prefer it, the smaller opening will of course also work.

Refactory concrete... depends very much on the product you intend to use. It has been done and there are a couple of threads around here somewhere. Beats me if I can remember who it was though...

Anyway, enjoy your build and remember to post pictures as you go!

[Justin]

Re: Some design questions on Pompeii oven

Thanks Frances. I didnt know if anyone had used a refractory concrete dome before, i might do bit bit of searching. I just dont want to go to all this effort and have an oven that does not work too well!
I might reconsider 1m wide opening, i seem to change my mind about things every second day

[tdibratt]

Re: Some design questions on Pompeii oven

My storage area opening is probably 1m wide and I do not have any blocks or steel lintel over the opening. I simply kept the blocks 1m apart when i fomed the walls and then poured the concrete over top. Lots of rebar in the concrete slab is key.

It's worked for me and this is the second one I've done adopting this design.

Regards

[Justin]

Re: Some design questions on Pompeii oven

Thanks tdibratt. Im going to dry stack the blocks first, then see what i like the look of best, at lease i know i have option of 1m now thanks!

[dmun]

Re: Some design questions on Pompeii oven

Around here, in the US, Firebrick is much cheaper than refractory concrete, so the preference is for brick domes. There are a lot of refractory products, some are solid, some insulating, some cure at room temperature, some need heat curing. It's impossible to make generalizations, other than that you shouldn't commit to a product without being able to talk to the manufacturer and find out if it's appropriate for your application.

[Justin]

Re: Some design questions on Pompeii oven

Ok, I'm using refractory bricks instead, its just going to be easier. I can actually get the refractory concrete and bricks etc for free so price wasn't an issue. Its handy having a relative in a steel works plant

[david s]

Re: Some design questions on Pompeii oven

I've found the refractory castable is tricky to use, especially if it's your first time at it. It is very temperature dependent ie. if your material or water is too warm the stuff goes off very quickly. The amount of water required is also critical, it's not as forgiving as normal concrete.

[Justin]

Re: Some design questions on Pompeii oven

I've found the refractory castable is tricky to use, especially if it's your first time at it. It is very temperature dependent ie. if your material or water is too warm the stuff goes off very quickly. The amount of water required is also critical, it's not as forgiving as normal concrete.

So looks like bricks really are the way to go then. Thanks for advice david

[dlgeis]

Re: Some design questions on Pompeii oven

you can easily span 1 m using 3" x 1/4" angle and pouring a proper rebar reinforced bondbeam.

Refeactory morter I have used needs to be drier to achieve max strength so you pour it into flat forms and vibrate the air out. This process gets complicate with curved complex shaper because you need a 3d mould etc. Also large refractory castings tend to crack due to steesses fron uneven heating and the resulting uneven expansion. It's just so much easier building with small units like bricks when building large complex shapes.

Doug

[Justin]

Re: Some design questions on Pompeii oven

Thanks Doug, im am going to stick with smaller opening as it seems to work for me in terms of the look i want. I will be building the dome for bricks though so no worries there

[boofalu]

Re: Some design questions on Pompeii oven

I have seen an oven built completely with refractory mortor. It was very basic but seemed to work ok for just cooking pizza while drinking beer. The multi national company I worked for had pallets of the stuff that they were going to throw out but some of the guys put it to use.
they did have problems with cracking though

[Justin]

Re: Some design questions on Pompeii oven

Haha boofalu. Cooking pizza while drinking beer, now who would want to do that man i cant wait till this thing is functional.
btw i have started a thread to track the progress of my oven with photos etc, you can find it here