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Post by carlszone on Jul 10, 2015 13:18:54 GMT
Hi there,
I have completed my plinth and now going onto the under oven floor insulation layers.
The gap between my plinth floor and where my oven floor will lay is 20cm, which I am aiming to fill with a layer of wine bottles and sand, followed by fireclay mortar and then storage heater bricks. Is this over-kill?
I was going to lay my fireclay oven floor on top of a slight bed of builders sand and cemented together with castable mortar.
Your advise would be greatly appreciated.
Regards
Carl
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Post by carlszone on Jul 10, 2015 13:23:21 GMT
Following the floor, I will be building my dome and looking at building a sand dome 80cm diameter and 40cm high and covered with damp newspaper.
I will create 3 layers on top of each other:
Layer 1 - Fireclay mortar mix (homebrew)
Layer 2 - Fireclay mix with sawdust added
Layer 3 - Firelclay mortar with perlite.
The walls will be 20cm thick all over which leaves me 30cm at the front to build my brick arch and the chimney between the dome.
Are these layers advisable or should I change the various ingredients?
Regards
Carl
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Post by cannyfradock on Jul 12, 2015 15:22:46 GMT
Following the floor, I will be building my dome and looking at building a sand dome 80cm diameter and 40cm high and covered with damp newspaper. I will create 3 layers on top of each other: Layer 1 - Fireclay mortar mix (homebrew) Layer 2 - Fireclay mix with sawdust added Layer 3 - Firelclay mortar with perlite. The walls will be 20cm thick all over which leaves me 30cm at the front to build my brick arch and the chimney between the dome. Are these layers advisable or should I change the various ingredients? Regards Carl Hello Carl.....welcome to the forum. After reading your 2 posts it seems like you are building a type of refractory concrete oven using the traditional clay oven building techniques. I have seen quite a few clay builds (including the one from our Moderator "Rivergirl") using the sand and glass bottle techn. as an insulation layer. They seem to work well but I go for the easier option of laying thermolite blocks on flat, then my fire-brick hearth. The storage heater fire-bricks make a good finished hearth. Nothing is overkill regarding wood-fired ovens especially when it comes to the insulation layers. Your layers of the dome will be fine as long as they have some substance. Your first layer is a homebrew layer. This normally consists of dry fire-clay, hydrated lime, cement and sand at a ratio (ratio is often debated) of about 1:1:1:6. I think that if you using just sand, then this may prove to be layer prone to cracking. You should substitute the sand for "refractory concrete"....or even just add 6mm granolium chippings (available at most builders merchants)and maybe change your ratio to 4 parts chipping, 2 sand then the 1:1:1.....this will turn your proposed refractory mortar layer into a refractory concrete layer....the same refractory qualities but much more strength. Layer 2 and 3 will achieve similar results. By adding fine wood-chips (not saw-dust) ..or snippets of straw will create a honeycomb layer effect which will give the dome it's thermal value, stopping the heat from exiting the dome. Perlite or vermecrete (vermiculite cement and water) will also give the dome a thermal heat stop allowing you to put a waterproof render on the dome. It sounds like you're heading in the right direction. Apologies if I have confused your build between a refractory concrete oven and a clay oven. I'm only 12 miles down the road (Newport)so drop me a PM if you want me to pop in sometime. Terry |
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Post by carlszone on Jul 20, 2015 21:46:06 GMT
Hi Terry, Thanks for the reply, had a busy time with son's graduation and work. I got back to my build over the weekend and finally finished my hearth / oven floor. I slightly changed the insulation layers, though started with a fireclay, sand and cement mortar base with 67 wine bottles, then encasing them with the remaining mortar. Next I mixed refractory mix and put in an initial base Layer then added four 600x600x38 slabs and covered them with 4 inches of the refractory mix.. Once it had hardened, I put a holding layer of sand and fitted the pizza bricks in a herringbone design. So now I am deciding what is the best method to build my oven dome, as opposed to my initial plans above. Materials available: 100 kgs of fire clay 200 kgs of builders sand 25 kgs of portland cement 25 kgs of hydrated lime 75 kgs of refractory castable (temp 1,400c) 29 Storage Heater Bricks 60 litres of perlite I am considering using the storage heater bricks with the refractory castable mortar to create the initial dome interior structure, then covering it with homebrew and finally the outer walls including perlite. I want to get this part spot on with the materials available and would therefore welcome feedback on my renewed plan structure as to whether it would work effectively and efficiently. Finally, I will be covering the dome with a shelter structure. Regards Carl Photo attached of completed structure / oven floor.  |
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Post by cannyfradock on Jul 21, 2015 17:45:44 GMT
Carl
"I am considering using the storage heater bricks with the refractory castable mortar to create the initial dome
interior structure, then covering it with homebrew and finally the outer walls including perlite."
....normally the storage heater bricks are about 8" x 8" and 2 inches thick. They will make a great substitute for the 42% Alumina content fire-brick that we normally use. Not quite as efficient....but they will work well. As you only have 29 you will have to cut them in quarters giving you 4" x 4" 2 inch squares...depending on internal diameter that may be enough. If not just give me a shout ....I have a good quantity of fire-bricks 3 inch, 2 inch and 1 inch. Before cutting fire-bricks we soak them in water. This makes it easier to cut them and saves the masonry blade....it should also work for storage heater fire-bricks.
I'm a bit confused with your use...and terminology of "castable mortar" and "homebrew". When building a fire-brick Pompeii dome you use the homebrew mix of sand, OPC cement, hydrated lime and fire-clay (usually in granular form)at a ratio of 6:1:1:1.......if the sand is very gritty and course you can head towards a 4:1:1:1 ratio. If you are not cutting your bricks in the "trapazoid" fashion of cutting your bricks on all 4 sides....then a refratory mortar or "Homebrew" is needed (like I do) as the outer edge of the brick will need a lot of mortar. You probably know but imagine a hedgehog when curled in a ball. The inner spines touch each other but the same spines on the outer edge have a massive space between them. The Homebrew can plug these large gaps and give a relative refractory quality as your fire-brick.
You mention castable mortar. Me thinks this is castable concrete which is very gritty in texture and would be perfect to cover the dome when built before using your perlite layer (never used perlite myself but I presume it's like a layer of vermecrete (vermiculite, cement water mix)
Looking again at your last post I think I have covered your question. If not then ask some more. I might miss your reply on the open forum so drop me a PM if you don't get a reply. If you want me to pop down it's no problem....again use the PM for contact details.
Love your hearth floor btw. No criticism but I normally lay the floor diagonal to the entrance. This just makes it easier for the Pizziola......if you have any corners of the hearth bricks that may catch the peel when in use, simply grind them down with a masonry blade in a 4" angle grinder....before you start building your dome...
Terry
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