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josh_r 11-05-2013 12:02 PM

Using rock instead of brick
 
Hello all

I am planning to build an oven for my wifes father. We live in on the south end of Lima Peru. Due to the lack in quality of bricks here, I am thinking of using rock instead. The brick here is very brittle. I am guessing that rock would work the same as brick would, but with the higher density of rock, it would take a little longer to reach temperature, yet would hold the temperature longer. Would this be correct? Has anyone here built one out of rock? I also have to find a material here that will work for the floor and work as insulation. I was thinking about a rock floor with a thin layer of sand and I can place flat tile as a base and it can easily be replaced when it breaks as I wouldn't expect the tile to last long. Things here in Peru are not made with the same quality as they are made in the states and other countries. Any advice would be awesome!

Josh

mrchipster 11-05-2013 05:58 PM

Re: Using rock instead of brick
 
Have you tried to visit a local pottery and see where they get bricks for their ovens, I am also sure you must have some local foundries that also may be able to source brick, commercial furnace companies would also use fire brick. Not the guys who do home heating but the ones that do heat plants for big buildings. Try to set up a meeting with the facilities manager for a bigger company and pick their brain.

The wrong type of rock could explode at worst or spall quickly. You may be better off with a well built cob oven and spend just enough to get brick for the floor.

josh_r 11-05-2013 06:39 PM

Re: Using rock instead of brick
 
Thank you for the reply Chip. I am afraid that there are no good brick manufacturers in Peru. the standard here is incredibly low. The bricks they make here fall apart after a few years being exposed to the climate in Lima. The terra cotta bricks they use for building are incredibly weak and are hollow. There is absolutely no need for high quality brick here in any trades, so they simply do not make it. It is very very difficult to get Peruvian companies to make anything of quality I am finding out. This is why I asked about using rock. I have also thought about making m own adobe bricks and firing them to strengthen them. Comments?

brickie in oz 11-05-2013 10:21 PM

Re: Using rock instead of brick
 
Hi Josh.
Get yourself some local rocks, build a fire around the rocks and slowly increase the heat of the fire, if you increase the heat too soon the rocks will fracture, but may not if you take it slowly.
The rocks will fracture if you just chuck them in the fire too which is why you would have to take it slowly.

Choose the rock type that does not fracture or explode with heat, most igneous or volcanic rock should work out ok, sandstone may be good too as it has no crystal structure.

mrchipster 11-06-2013 02:59 AM

Re: Using rock instead of brick
 
Quote:

Originally Posted by josh_r (Post 165003)
I have also thought about making m own adobe bricks and firing them to strengthen them. Comments?

Instead of making adobe bricks just go straight to the cob dome. Adobe brick is made from identical materials search cob ovens on here there are several people who have done them and they can help you out. I have not done one so I am not a good resource.

stonecutter 11-06-2013 04:28 AM

Re: Using rock instead of brick
 
Quote:

Originally Posted by brickie in oz (Post 165009)
Choose the rock type that does not fracture or explode with heat, most igneous or volcanic rock should work out ok, sandstone may be good too as it has no crystal structure.

Actually Al, igneous stone will be more susceptible to breakage during thermal cycling, especially granitic types with a high quartz content. Sedimentary may hold up better, but useless there is some wondrously durable kind in Lima, I think the surfaces would become friable after a relatively short time.

I think Chip is onto the right solution here, and I will add to it that the OP should seek a clay source....maybe a potter or a natural deposit.

Save the stone for the finishes.

Tscarborough 11-06-2013 05:14 AM

Re: Using rock instead of brick
 
Crappy soft brick will make a fine oven, rock will not.

josh_r 11-06-2013 05:31 AM

Re: Using rock instead of brick
 
Thank you all for the replies. This gives me a much greater idea of the direction I should head. As for the soft brick here making a fine oven... If it can't make a fine wall, how is it going to make a fine brick oven? The walls they build out of brick here can't even withstand the mild climate here. They crumble into nothing. I just cannot see these bricks holding up to the extreme temperatures and expansion/ contraction as a good brick can. You are never going to know what I am talking about unless you see it for yourself... Maybe I will take a picture for you guys some time.

So it sounds like my best option is to look into the cob ovens. Thank you all very much. This is a great informative group!

Josh

Tscarborough 11-06-2013 06:07 AM

Re: Using rock instead of brick
 
I know exactly what type of brick you are talking about and even how they are made. What kills brick in the environment is water and cold, neither of which should be an issue in an oven.

josh_r 11-06-2013 08:03 PM

Re: Using rock instead of brick
 
Have you seen the brick in Lima?


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