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maxsbarandgrill 09-01-2013 03:26 AM

In Sudan, Limited Materials, Help!
 
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Okay, so I am in an area where there are no fire bricks, no perlite, no fancy materials. I do have some primitive red brick that is fired but each brick is a different size (roughly the same length/width but depths are uneven on every brick. I have access to usual Portland cement, river sand, lime. I have been able to construct a metal skin. Since the brick is all such poor quality this was a must, I will still use a sand base with these red bricks for the floor. I managed to bring ceramic blanket in my suitcase so that is a plus. Every time I read mortar recipes they all include ingredients I have no way to access. There is a tremendous amount of volcanic rock here that can be crushed into a powder though. The metal skin I constructed is 50" wide, 40" long, floor to ceiling height will be approx 29".

So long story short, can anyone recommend a mortar recipe based on my limited materials? Are my oven dimensions okay? I can still increase the length by 5-6" and decrease the dome height up to 8".

This is a barrel type oven, not a proper dome. I plan on insulating using first a layer of red brick, then ceramic blanket, aluminum foil, chicken wire (mesh), then 5 to 1 sand/cement mixture to cover it all.

Any help greatly appreciated. I need to get this done. Thank you!

Max

thickstrings 09-04-2013 05:42 AM

Re: In Sudan, Limited Materials, Help!
 
I might sugest you ask this in the "Other oven types" section, Where there are many builders who are using steel and "cob"..The soil in the picture looks quite red....perhaps a lime/clay mix over the insulated steel on a brick floor over a volcanic rock mix....

maxsbarandgrill 09-04-2013 07:01 AM

Re: In Sudan, Limited Materials, Help!
 
Alright, thank you.

stonecutter 09-04-2013 07:57 AM

Re: In Sudan, Limited Materials, Help!
 
Quote:

Originally Posted by maxsbarandgrill (Post 160799)
I have access to usual Portland cement, river sand, lime....

You have more than some people have. You can use the portland and lime to make a brick mortar, but for finish work only only...do not use it near heat. Type N is what you want with soft red brick or lime mortar ( trickier to use without experience.)

The volume ratio for making Type N is 1:1:6 Portland,Lime,Sand.

Keep your floor brick away from the steel walls by 1/4". Just screed a thin layer of sand over your floor insulation* to level them. Plan on changing out broken brick frequently....though if your clay brick has a high silica content they might hold up better.

*I would make an insulation slab out of the volcanic material...see below for suggestions.



Quote:

Originally Posted by maxsbarandgrill (Post 160799)
There is a tremendous amount of volcanic rock here that can be crushed into a powder though.......So long story short, can anyone recommend a mortar recipe based on my limited materials?

Is it Pumice? Can you get volcanic ash too? They are Pozzolans, and you can mix them with lime to make a more heat tolerant mortar...this would be something closer to what the ancients used on their ovens, which most of the ones on this site are modeled after. The only ratio for Pozzolan based mortar I have come across is 2:1 - Pozzolan, Lime.....no partland. See below for what you can use this for......


Quote:

Originally Posted by maxsbarandgrill (Post 160799)
I plan on insulating using first a layer of red brick, then ceramic blanket, aluminum foil, chicken wire (mesh), then 5 to 1 sand/cement mixture to cover it all.

This is were it gets tricky. I don't think that brick will last very long against the steel....but you need some thermal mass to store heat, because the steel will cool very quickly without a large live fire.

Consider making a thermal layer containing the crushed (Pumice?) lime and sand about 3.5" thick. I would go 2:1:6 to start with...make a small batch and see. You might want to go a bit leaner, like 2:1:8. [Poz,Lime,Sand]

Or try crushing some of your clay brick into powder and replicate the standard mix used on this site. Ratio 1:1:1:3 portland,clay,lime and sand ( though I think this ratio is too rich...and made mine 1:1:1:4.5) Experiment time.

Next, as you are applying this thermal layer, I would imbed the wire mesh at two layers at 1", then 2".

After this layer dries, cover it with your ceramic blanket. You still need more insulation than what a single blanket will provide. If all you have to work with is the above listed material, then crush more of the volcanic (pumice?) into small pieces, like 1/8"-1/4", and treat it as Perlcrete or Vermicrete.....ratio will be 1:8-10 - Portland, Pumice.

As a finish, you can stucco this layer, then either leave it or brick over.

Interesting project....keep the forum updated, and don't forget pictures.

Hope this helps.

stonecutter 09-04-2013 07:59 AM

Re: In Sudan, Limited Materials, Help!
 
To be clear, if you use the volcanic rock in a mortar mix or for the thermal cladding, then crush it into powder. For insulation, crush into small particles.

maxsbarandgrill 09-08-2013 07:24 AM

Re: In Sudan, Limited Materials, Help!
 
Thank you all for your great suggestions. I will post up more pictures and progress this week. Cheers!


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