I've laid out 4" of ceramic fiber blanket and have started my stucco render as a finish. I'll post pics tomorrow.
For the stucco recipe, I have been using david s recommended recipe ratio of 4:1:1 (Sand: Hydrated Lime: Cement) but without hydrated lime as I have not been able to am not able to source it. So, technically the ratio is really 4:1 ( Granite Sand: Cement).
Will the lack of hydrated lime be a problem? I hope not since I'm about 1" thick so far with the render and approaching the finishing coat!
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42" Pompeii Oven in Jamaica
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Originally posted by wthwaites View PostI got the correct fibers! So i managed to pour the slab for the squirrel tail chimney.
Now I can move on to the final stages for the build - insulation and then the final render!
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Originally posted by wthwaites View PostI was told it was glass fibres for concrete; I will double check tomorrow. If they aren't, they can't be used?
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Originally posted by wthwaites View PostI was told it was glass fibres for concrete; I will double check tomorrow. If they aren't, they can't be used?
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I'm rooting for you. I have a mental problem with needles of any kind lol. I'm looking forward to how it all turns out.
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I got Fibreglass fibres, so I'll be moving ahead with casting the slabs with both that and the polypropylene fibres. That's the best I can do with what I can source. Lets hope for the best!
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The reason melt extract fibres (stainless needles) are recommended is that being a very small diameter they present a much larger surface area than thicker stuff. This enables them to dissipate their heat more easily to the refractory that surrounds them, thus reducing expansion issues of the two different materials. In normal ambient conditions eg red in a concrete beam the rate of temperature change is slow enough for the two materials to be quite compatible. But when extreme heat is applied > 200C/hr, then problems are likely to occur. You could try using some AR fibreglass fibres in the castable, glass has a melting point of around 900C so is well above our temp range.I use them as well as the stainless needles.Last edited by david s; 12-15-2020, 09:12 PM.
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So the fibers aren't needed?
I was able to find needles, but they weren't stainless steel and was only available in 55 lb buckets at $250 - way out of my price range! For the amount I would be casting (essentially a 2' x 4' x 3" triangular slab divided into three pieces), I also think that the purchase would be a waste.
I'm all ears for alternative solutions. I may be able to find stainless steel threaded rods. Will that suffice?
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The polypropylene fibres will melt at 160C so are not suitable for reinforcing in this application. Once they have melted they leave behind a network of minute pipes that steam can pass through. This reduces the incidence of steam spalling provided heat up is taken slowly.
The recommended reinforcing for refractory is stainless steel needles, but their use is not mandatory. Their drawback is their expense and difficulty in handling when placing the castable.Last edited by david s; 12-15-2020, 08:18 PM.
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