using second hand bricks
Hi - I got my fire bricks - they are second hand, apparantly having been taken from a dismantled kiln. Although many still need to be cleaned properly, most are in pretty good shape and I hope to be able to get an even floor done with them.
I have two questions on this - first of all the building materials section of the pompeii plans mentions that approx 100 bricks are required for the floor and another 180 for the dome. Does this mean using 180 half bricks (or 1/3 bricks following kiwipete's design) to build the dome and therefore only really requiring approx 100 bricks for the dome?
secondly, once the dome is done :cool: would the curing process for these used bricks be the same as described elsewhere on the forum or does the fact that they have been already fired up change the process?
The curing time doesn't really refer to the bricks as such. If you use refractory mortar, and even if you don't, you must dunk the bricks in a bucket of water until they stop hissing before the mortar is buttered on. Miss this step and porous firebricks will suck the moisture right out of the mortar, and the mortar will not stick to the bricks at all. So, you'll have wet bricks and wet mortar to contend with. Mortar takes 28 days for a full, chemical cure. After that, you'll have to drive off residual moisture in the bricks themselves with a week or so long series of very small, but increasing fires. There is no way around this if you want to avoid cracking. One of those facts that drive us all round the bend.
I've wondered at the quantities given in the Pompeii design myself...
My supplier provides 25 floor tiles measuring 230x230x50mm in its 1m internal diameter dome oven 'kit', which seems to cover the oven floor nicely (I may still round the base tiles so they fit nicely into the inner perimeter, which is apparently the objective of the seasoned oven builders in this forum...) Incidentally, it might be worth checking out if one can 'wash' a refractory mix over the floor tiles to fill the gaps and crevasses so as to obtain a smoother finish? Perhaps one of the experts will oblige with his/her opinion...
On the 'seconds' issue, it may depend if they are remanufactured tiles made from ground up firebricks that are then re-pressed and fired (?) - in this case my supplier assured me there was no rpt no difference in performance, even though these 'seconds' only cost $A2 ea. instead of $A3.80.
I still ordered the dearer ones - 35 for the top portion of the dome, including a few extras. These tapered bricks are supposed to be cut in half each to make a smoother curve (as are the 70-odd bricks for the lower portion of the dome that are cut/pressed to a slighly lesser taper). The ones I got for the top portion 'looked' to me like seconds, spotted with lots of dark/rusty inclusions, but I was assured this was merely due to "a different mix"...
The full materials list for the 1m (39in) diameter dome oven was given in another posting a little while ago - I can't seem to find it offhand.
Some 'progress' snaps of my journey toward the Pompeii dome - if you can call the slow pace 'progress' - are at http://www.picasaweb.google.com/lutz...orno_del_gallo
(I didn't want to burden this excellent site with such nondescript stuff but will upload actual construction photos here later in the game...)
thanks for your replies - The curing process makes more sense to me now and probab;y will not make any difference no matter how used the bricks are themselves - we have to think of the oven as a whole mass (mortar plus bricks) that must be cured together.
I'll try to find the full materials list on the forum that you mentioned and take it from there. The list I have referred to so far is the one for a 42" oven given on the original plans on this website. I am still undecided as to the final size of my oven but will build the base for a 42". I should be poouring the foundation concrete tomorrow.
Great pics carioca - your oven is looking great - It's going to be a tough challenege even just keeping up with you lot!
I'll be posting another question regarding the building of the dome - would appreciate your thoughts.
If your folks get more accurate brick counts based on the size of the oven you build, brick size, cuts, etc. -- please send it to me. I am always updating the FB.com web pages, and can easily update the Materials List page to give more helpful information.
Let us know how you bricks buys work out.
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