Cast Refractory Pizza Oven Build

[abulsamman]

Hello everybody,

after going through the forum and learning lots, I have decided to finally start my build.

Initially I thought of building a brick oven, but then thought of the difficulty of finding the right bricks and cutting them the right shapes and sizes. Also, I thought it's going to take alot more effort than a cast refractory oven..

Anyway, I come from Jordan and I believe I'm the first from my country in Forno Bravo's forum At the moment spring is coming up so its probably the best time to start a build. Jordan is a hot and very dry country, so trying to beat summer weather is probably a good idea.

I have been inspired to to do a cast refractory oven build by JoeyVelderrain, and several others on this forum. However, one thing I'm worried about is the availability of materials here in Jordan.

In regards to the cast refractory, I have not found the ready mixed cast refractory with aggregate, but rather the basic fondu mortar. I am wondering if i can just mix it with sand and regular gravel should make it ok for the cast build?? any help on this is much appreciated, including ratios..

The oven size is a 1m low vault oven with a wall thickness of 5cm or 7.5cm, any advice on that also would be appreciated. Cooking floor will either be tiles or bricks have not decided yet. Attached are some pics of the selected location including the dig for the foundation and basic plans for the build.

Pouring the foundation should be done in a couple of days, and the oven stand will follow shortly after.

Can't wait to cook my first pizza

[abulsamman]

Re: Cast Refractory Pizza Oven Build

Today got the foundation poured, and tomorrow going to lay the blocks..

[david s]

Re: Cast Refractory Pizza Oven Build

Regarding your castable mix using sand as an aggregate, you are in unchartered territory, but I think it will work ok. One of the main problems in making your own brew is to get it plastic enough to make it stick well to your form. Fondu and sand may not produce this, you will need to test a small amount first. Another problem is that proprietary castables contain fibres that burn away at low temp leaving tiny pipes that water can escape through to prevent blowing. You should add something that will do this. If you can find the fine polypropylene fibres sometimes added to concrete for compression strength they will suffice as they melt at 160 C failing that try some animal or human hair. I think also the addition of manure, often used in cob ovens, does the same trick provided it has plenty of undigested fibre (horse manure) I think it also has the quality of making the brew more plastic which helps in the first point I made.

[wotavidone]

Re: Cast Refractory Pizza Oven Build

Could you just take a natural fibre rope, such as sisal or hemp, and cut into short lengths, say 30-40mm, and fray that to get your fibres?

[david s]

Re: Cast Refractory Pizza Oven Build

Yeah, that's another option, but it won't improve the plasticity of the mix. The beauty of the polypropylene fibres is that they melt at a low temp.(160 C), whereas the sisal rope, or hair for that matter, may not burn away until a much higher temp has been reached, by which time you might already have steam explosions. Do some tests with different materials in a domestic oven to see at what temp they burn.

[abulsamman]

Re: Cast Refractory Pizza Oven Build

Thanks David for the info. Not sure if I'm going to find the Polypropylene fibers, but I sure will try to find them and will defenately make some tests. Hopefully my oven won't stink afterwards and will let you know how it turns out ..
Do you think it is necessary to add gravel for grog in the mix??

Karim

[abulsamman]

Re: Cast Refractory Pizza Oven Build

Today got the blocks layed and getting ready for pouring the hearth..

[abulsamman]

Re: Cast Refractory Pizza Oven Build

Got a more detailed plan for the oven. Would appreciate suggestions - comments from all you experienced builders..
Still have to do a cross section drawing, will post it once complete.
Karim

[david s]

Re: Cast Refractory Pizza Oven Build

I wouldn't add gravel to the mix,it will tend to make the mix less plastic and weaker.for those polypropylene fibres, go to someone who specializes in concrete engineering supplies. You need to mix it about double the time that you would think, so they disperse properly.

Your entry is quite deep. A shallow entry makes using the oven much easier IMO.

[abulsamman]

Re: Cast Refractory Pizza Oven Build

Thank you David, do you suggest I push the inner arch inside the dome? If so how much??

Thanks,

Karim

[david s]

Re: Cast Refractory Pizza Oven Build

Yes you can. you can even have the flue placed slightly over the top of the oven door to make it even shallower, but make sure you have a reasonable funnel (wide but shallow) leading to the flue pipe.

[abulsamman]

Re: Cast Refractory Pizza Oven Build

Yes you can. you can even have the flue placed slightly over the top of the oven door to make it even shallower, but make sure you have a reasonable funnel (wide but shallow) leading to the flue pipe.

Not really sure if I wanted to put the flue above the oven door, but put it around 1cm away..

Does this seem better to you??

Thanks,

Karim

[david s]

Re: Cast Refractory Pizza Oven Build

Not really sure if I wanted to put the flue above the oven door, but put it around 1cm away..

Does this seem better to you??

Thanks,

Karim

Yes, you will be glad you have reduced that long tunnel.

[abulsamman]

Re: Cast Refractory Pizza Oven Build

Got the the hearth poured today and bought the ceramic board and blanket

I only found a thickness of 4cm for the board and 2.5cm for the blanket hopefully that would be enough for the insulation..

[abulsamman]

Re: Cast Refractory Pizza Oven Build

Drew a diagram of the front view of the oven:

cooking floor diameter : 100cm
oven height (highest point): 42cm
oven sides height: 30cm
outer arch width: 60cm
outer arch mid point height (highest point): 31cm
outer arch sides (lowest point): 21cm
inner arch or door lip is 2.5 cm all round
inner arch width is 45cm
inner arch mid point height (highest point) : 26cm
inner arch sides (lowest point): 20cm

comments suggestion appreciated, really don't want to get anything wrong or regret anything..