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Post by Calaf on Feb 6, 2012 22:17:36 GMT
Calaf - it's looking good and so well planned. I've got salt leaching out all over my vault so guess it is normal. I made the error of tasting it to confirm it was salt and I suspect those crystals have some pretty pungent chemical lacing as my tasting was followed by some most ungentlemanly behaviour. Looking forward to the next stage of your build. All the best, Francis
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Post by Calaf on Feb 6, 2012 22:18:34 GMT
The buttressing of the pier wall is almost complete. The first stage with a 4:1:1 perlicrete, the second a 3:2:1 vermicrete. I’m not entirely content with this solution as it provides a, albeit narrow, thermal leeching vector to the base that I would have preferred to avoid. In retrospect, I should have bought more CalSil board. Perhaps an external steel bracing rig just above the spring line and over the arch would have been better, if more costly.
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Post by Calaf on Feb 6, 2012 22:19:39 GMT
After a week the mortar joins in the skewbacks are still slightly damp and can be impressed with a fingernail. Ordinary sand/portland mortar would easily resist the shear of the vault but I have little confidence in this wet air-setting cement mix. For peace of mind I have added 20mm of cladding reinforced with plasterers beading to brace 70% of the wall length. The mix was 4:2:1 sand, fireclay and portland.
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Post by Calaf on Feb 6, 2012 22:20:17 GMT
Wife is complaining my fingers are rough. I have top-rendered the base. I think I will lime-wash it rather than paint it. Must stop procrastinating and start the arches.
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Post by Calaf on Feb 6, 2012 22:23:53 GMT
cement and lime are not your skins best friends, i found this out and promptly went and found some gloves for when I resume building, just waiting for the temp to raise slightly as I am a wuss, also doing to dome so did not want really slow curing as it would drive me nutts i fear. it might be air setting but I am sure there is some chemical curing thats going on? looks great tho Hi Turkey My mother always told me not to point with my fingers. I didn't realize she meant mortar. The wife gave me some poofy cream to use but I declined and said that having rough hands I had at last discovered my masculinity.
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Post by Calaf on Feb 6, 2012 22:24:23 GMT
My second render on the base has cracked. Only rendered a few things before and never had it crack on me. Added lime for first time but maybe it was the frost. And I was quite proud of how smooth I got it. Might I get away with painting a soggy mortar mix over it?
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Post by Calaf on Feb 6, 2012 22:31:11 GMT
no idea on the render, but loving the 4chan /b3ta board images all aboard the lulz ship.... toot toot. .-- .-""-. . ) ( ) . ( ) ( . / ) . (_ _) 0_,-.__ . (_ )_ |_.-._/ . ( ) |lulz..\ . (__) |__--_/ . |'' ``\ | . | [Lulz] \ | /b/ . | \ ,,,---===?A`\ | ,==y' . ___,,,,,---==""\ |M] \ | ;|\ |> . _ _ \ ___,|H,,---==""""bno, . o O (_) (_) \ / _ AWAW/ . / _(+)_ dMM/ . \@_,,,,,,---==" \ \\|// MW/ .--''''" === d/ . // SET SAIL FOR PIZZA! . ,'_________________________ . \ \ \ \ ,/~~~~~~~~~~~~~~~~~~~~~~~~~~~ . _____ ,' ~~~ .-""-.~~~~~~ .-""-. . .-""-. ///==--- /`-._ ..-' -.__..-' . `-.__..-' =====\\\\\\ V/ .---\. . ~~~~~~~~~~~~, _',--/_.\ .-""-. . .-""-.___` -- \| -.__..-
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Post by Calaf on Feb 6, 2012 22:32:51 GMT
Calaf If the render has cracked, chances are it hasn't taken to the render beneath it and might just start to flake off. If you tap it and it sounds hollow then it might be better to remove it while it's still relatively fresh. Plus it will be difficult to patch up and it may annoy you in the future. If you decide to remove it, then let us know and if you want advice on a good render mix. Terry Turkey Reserve me a place on the Lutz ship. Terry
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Post by Calaf on Feb 6, 2012 22:34:00 GMT
I used a 4:1:1 mix. Too much lime? I usually give a PVA wash beforehand but didn’t this time thinking the lime was going to improve adhesion.
Giving it a tap all over it’s just an area about the size of a tea-cup that has popped. The coat was still slightly pliable so pushing it back and washing it with dilute mix seems to have helped and it has tightened up overnight. You can hardly see it now. I’m going to leave it and lime-wash it a few of times. If it breaks, I’ll fix it.
I was miffed because this was the first time I have managed to get a smooth finish on render and was feeling quite proud of myself up to then.
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Post by Calaf on Feb 6, 2012 22:35:13 GMT
If it were the frost, your render would not have cracked, more likely disintegrated into a loose particulate mess - much like the mortar I used a few days ago to level some paving slabs for decking supports. Given my line of work, I'm used to quickcrete - which sets solid in 5 minutes flat, even underwater. Poor old Portland doesn't compare...... The perils of living in the frozen North. Ah, my first post. Ahoy, Wood & Pizza Oven UK people :-) Hi Bighairyal, welcome to the best wood oven forum on the planet. Seeing as my work-rate is a blistering 30 minutes per sqm of render I don't think I could have got your stuff out of the bucket before it set.
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Post by Calaf on Feb 6, 2012 22:36:06 GMT
Calaf If it's such a small area that has popped you should be alright.....and it sounds like the finish will turn out OK. .....hello Al...welcome aboard. Terry
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Post by Calaf on Feb 6, 2012 22:36:50 GMT
Progress! I’ve started on the vault. To minimise any cracking of the ready-mix cement, I butter half the brick height with a wedge of mortar just to secure it in position. When all four arches are complete I will backfill with a sand/fireclay mix with crushed clay roofing tiles and quarry tile offcuts. You can see the joints are not perfectly lined but not bad for a first effort.
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Post by Calaf on Feb 6, 2012 22:38:46 GMT
Mark " You can see the joints are not perfectly lined but not bad for a first effort."Don't hide your light under a bushel. Brilliant workmanship and I really like the way you are using different mortar mixes in the separate stages of your arched vault construction. ....lovin your build..... Terry Thanks chaps. However, despite my careful calculations of brick angles I still found that the keystone had to be trimmed by 2mm. Just goes to show, experience trumps theory. As you can see, that one I badly misjudged how much to cut, so flipped it over and cut it again.
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Post by Calaf on Feb 6, 2012 22:39:41 GMT
To stagger or not to stagger.
Going back to a point made by Bookemdanno, there is the question of staggering joints in the vault. A tricky thing to do requiring your arch former to be the length of the oven.
But I wonder, is there an advantage to NOT staggering the bond in an oven’s vault? Under thermal stress, tensions generated by expansion will be released at the weakest points in the structure, the mortar joints. If the structure needs to move slightly, fractions of a millimetre, it will do so along these weak lines. With a staggered bond the tension will need be far greater before it is released but is likely to do so more dramatically, resulting in larger cracks. (Think of tectonic forces that generate earthquakes. If the fault line stresses are not releived by regular small shocks then the pressure mounts and is released in a big 1906 type quake.)
An un-staggered vault should be more flexible and as the roof takes no dynamic load the strength of a staggered bond is not required.
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Post by Calaf on Feb 6, 2012 22:41:49 GMT
Calaf, I personally don't think it would have MAJOR consequences either way. If you really want to analyse it I reckon the un-staggered approached would be better, because in general the fire is in one area of the dome - (at the back by the time it's established) meaning the far arch can expand without putting a lot of force on the other arches. This may be seen as a bad thing though - given that this could be seen to weaken the bond between the two arches. I ultimately don't think it will make much difference. I went on the un-staggered approach. Calaf I'm with Duncan on the vault/arch construction....staggered or not won't many any difference (in my opinion). Terry Yes, I don't think staggering or not would make any significant difference to a garden oven. Just thinking aloud and responding to a comment.
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