Hearth and Dome construction questions Pompeii Oven Construction Discuss Hearth and Dome construction questions in the Pizza Oven Design and Installation forums; Asparapani: In some of my old answers I had explained how to work with vermiculite/cement mixture and percents between them. ...

[arevalo53anos]

Asparapani:



In some of my old answers I had explained how to work with vermiculite/cement mixture and percents between them.

If is your intention to use the vermiculite/cement to isolate your dome, your could go as high as 8:1, that is better as isolation.

To do the mix, it will better to mix the vermiculite with the cement when dry, this permit each particle of vermiculite to be surrounded by cement before be wet.

Whit the mixture perfectly homogeneous could be better to shower it with a light stream (more a smooth shower) and mixing at same time, to not “wash” the cement from the vermiculite particles.

Good work.



Luis

[asparapani]

hello all,

Yet another novice question that needs proffesional answering...

Is it possible to use high temp mortor paste,(the one to bond firebricks with) and cast it into a mold instead of refractory concrete?

I plan on making my molds throughout the winter in my heated garage so it will have time to cure. I'm still stuck on the dome mold technology.

cheers

[dmun]

Originally Posted by asparapani

Yet another novice question that needs proffesional answering...

You're right on this - You need a professional answer. Refractory mortar is not made be any wider than a brick joint. There are castable refractory materials that harden at room temperature, but other than a flue transition, no one here has much used them.

You need to talk to a refractory dealer. These places sell to people building serious things like kilns and boilers, and will have access to an applications engineer, who will be able to answer your questions. Refractory materials, even fireplace mortar, is expensive stuff, far more expensive than firebrick, and you don't want to cast up a big dome sector, and find that it's cracking on drying or firing.

[asparapani]

thanks for the profffesional suggestion....

I'll go speak to a refractory specialist

[crowtrapper]

Hmmm. I am working on the dome, and have done 4 courses, and it looks as if the 5th will be the last that can be done without some sort of formwork. I have used old common red bricks, which vary in size quite a lot, firebricks too expensive around here. ($7 each). Have used mortar only, no shims, to place the bricks, and so far it has worked OK. Using formwork will be a pain, and I have been considering making a precast refractory concrete dome section to finish the dome off, rather than laying more bricks.

Sounds as if this is not really possible - too hard to get a mix of concrete which will stand the heat and which will set at air temperature.

Filling a perfectly good dome with sand to make a sand form seems like a desperate measure. Any other ideas?

[egalecki]

I built mine without forms. Use something to prop up the brick- it shouldn't take more than a couple of minutes to set up enough to remove it. A stick would do, really. I used bamboo sticks (1/4 inch or so in diameter) for mine.

You can do the sand, but it's messy and you can't clean up the joints on the inside. Fighting gravity is possible, just be creative.

[crowtrapper]

Sticks - yes - good idea. It will only be for a couple more courses then I can build a small round platform to support the last couple of really small courses near the centre. Thanks. And maybe I'll use a bit more lime to make the mortar stickier as well.