Got these firebricks, how should I build a pizza oven with them?

[Fizz]

It would be best to stagger the bond on the arch for strength and integrity. By pre-making the arches there will be a long seam at each joint of the pre-made arch unless I am not understanding what you are trying to do.

If I use 4 and a half brick,I can turn every other arch 180 degrees and have staggered joints? I got to learn the slang used, so I´m googling a lot of words now ... If you look at the third pic, of two mock-up arches, that´s a staggered joint, right?

[UtahBeehiver]

Wont' you still have a long joint seam (circular) where each premade arch segment butts up to one another? Here is a pic from Tscar's build showing a staggered bond.

https://community.fornobravo.com/filedata/fetch?photoid=279192

[Fizz]

Wont' you still have a long joint seam (circular) where each premade arch segment butts up to one another? Here is a pic from Tscar's build showing a staggered bond.

https://community.fornobravo.com/fil...photoid=279192

That's true, I didn't think about that joint... Is it better to have the longer joints lengthwise, as in the pic you linked to?

[UtahBeehiver]

Point taken, if I think about it, even on a dome there is a long seam at each course. So I would do what works for you.

[Fizz]

Point taken, if I think about it, even on a dome there is a long seam at each course. So I would do what works for you.

Thanks for your input!

I think I´m going to make use of the fact that the winter is long over here, I´m eager to get started and the kids are away for Christmas, and get some refractory cement and pre-make the arches! If I add a second layer of bricks with refractory mortar on top of the curved firebricks it has to be strong enough. Then a layer of LECA + cement, and then insulation.

[Fizz]

Came up with another question, that I couldn't find an answer googling it..

Does anyone know if there's any risk in using my indoor fire place to clean the fire bricks? I have a stove that easily reaches the carbon burn off temperature, and could probably fit three or four bricks at a time... I usually fire it up every day during the winter...

The only issue I could think of is the water content in the bricks, but are there any other unknowns in the equation I'm missing?

[Fizz]

Well, I put one I've kept indoors for awhile in the stove , and it looks just about the same after firing yesterday...

Nice and clean... Doesn't smell of forest and moss any more....

Think I'll do it to all of them, in batches...

[Fizz]

Started building the base out of leca blocks. No need to cast a slab, as you see ... It´s solid rock...

Next I will build a form and cast a top/slab/hearth (what ever it´s called?) on the base. As you see in the picture, the base is U-shaped, and I wonder how I shoud dimension the concrete top to allow it to be unsupported btw the "sides". It´ll be supported in the back. The distance btw the sides is 80 cm (about 31 inches), and the depth is about 110 cm (app. 43 inches).

How thick should the top be, and do you think its a good idea to build the form like the piece of wood laying on the leca block in the picture? This means that the concrete top won't be supported by the entire surface of the leca block, but the top will use substantially less concrete. The leca block is 19 cm wide ..

Sorry about my bad english, I hope you understand what I mean... =)

[agrasyuk]

I'm not a structural engineer so no exact calculations for below. But from seeing different builds so far:
I would not go with slab thinner then 3.5" (90mm).
I would span the opening of the "U" with something iron .
i would strongly consider at least some sort of arch to help with the weight in front.
IMHO Wood form should go on the outside of the base so the concrete rests fully on it.
Depending on the size of planned oven you might even want overhanging slab , I would not go more then 6" (150mm) or so of overhang.
Rebar is a m must.

I'm sure you will get more structured replies.
Good luck!

[Fizz]

Thanks for the reply! My plan was to make it 100 mm thick, and use 10 mm diameter rebar...

I'll sketch up a few of the various designs I've considered and post them here...

[Fizz]

Coming along nicely .. =)
I decided to make a support in the center of the concrete slab, and using 90 millimeter of leca, and 50 millimeter of calsium silicate board to insulate the under the oven ...

Any input on the necessity of side support for the arch? I´m thinking of insulating the sides with calsil board and then cast a square ring of rebar reinforced concrete around the 10-15 centimeter lower part of the arch ...

[agrasyuk]

To me your perfectly cylindrical dome structure looks solid. It will surely support way more then its own weight. Buttressing the lower part of walls not going to hurt, but IMHO reinforced concrete is way overboard.

Unless what you really building is a reinforced plane shelter to protect your RC combat jet from getting preemptively bombed by your neighbor's RC airforce . Then of course you will need all the steel/concrete you can get

[UtahBeehiver]

Those arched bricks are turning out quite nice. Good job on herringbone floor.

[Fizz]

To me your perfectly cylindrical dome structure looks solid. It will surely support way more then its own weight. Buttressing the lower part of walls not going to hurt, but IMHO reinforced concrete is way overboard.

Unless what you really building is a reinforced plane shelter to protect your RC combat jet from getting preemptively bombed by your neighbor's RC airforce . Then of course you will need all the steel/concrete you can get

I hope you're right about that... It feels pretty stiff already, two and a half layer in... I do like to overbuild stuff, but this is kind of expensive and time consuming to do it with...

[Fizz]

Those arched bricks are turning out quite nice. Good job on herringbone floor.

Thanks! I ran out of the ordinary fire bricks, which is why I didn't finish the floor first....

More input on the need of buttressing the arch would be much appreciated!