Chimney bricks

[maxstutz]

Hi all
I am fairly new to this and just building my first oven with the intention to use mostly recycled materials... To come straight to my question: can I use clean recycled chimney bricks as my heat retaining bricks for hearth and dome of the oven? I was given about 250 of them each roughly 4 pounds heavy, that would certainly make for a fairly large oven I tried to search the internet and this forum but was unable to find any info on the topic...
If you have any knowledge or experience with chimney bricks I would greatly appreciate your help
I attached some pictures of the base that the oven will be build on...
thanks
Max

[UtahBeehiver]

Depends, post a pic, solid clays are the only possibility and that is questionable.

[maxstutz]

Here you go.... they are quite heavy around 4 pounds

[UtahBeehiver]

Sorry, can't say. Almost looks like a concrete brick due to the texture and not clay. Concrete certainly won't work.

[maxstutz]

Thanks utahbeehiver
unfortunately I have to agree that they look awfully similar to concrete bricks, the only thing that seems strange to me that they were used as chimney bricks with visible traces of soot on some of them... I conclude from that that they must have been exposed to some heat at least. I might take a brick to a shop that sells fire place stuff, maybe they can enlighten me further