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Post by deliams on Jun 16, 2012 22:05:38 GMT -8
 Your pizza oven looks lovely, you did a neat job fitting it into the concrete. I'm experimenting with fire clay and concrete mix with straw and sodium silicate after I noticed a refractory cement mix is being used in South American rocket stoves. I shall pass your mail on to Jed Guinto. A major ingredient is missing is sand because Crispin Pemberton who makes rocket stoves for Malawi noticed that sand tends to cool and heat at different rates to clay and therefore causes cracking. All the best with your pizza business!
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Post by Deleted on Jun 17, 2012 3:10:10 GMT -8
That is far to broad to be generally valid. It will depend on the kind of clay and the properties of the sand. Size, form and chemical composition of the sand particles will have big influence. Sharp-edged sands will give stronger structures than round-edged in any respect. Clays are mixtures of clay minerals with each unique thermal expansion coefficients, which, due to the lattice structure, differ in the dimensions. www.minsocam.org/ammin/AM50/AM50_212.pdfGanister a hard, fine-grained quartzose sandstone, or orthoquartzite is commonly used in refractory concretes. en.wikipedia.org/wiki/Ganister |
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Post by deliams on Jun 19, 2012 1:48:16 GMT -8
Thanks Karl, I appreciate those articles, I'm glad that there are other ways of building stoves that can use sand after all. |
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Post by deliams on Jun 19, 2012 2:51:29 GMT -8
I think your pizza stove is brilliant and I think its great you've used concrete sucessfully.. I was unsure about using concrete because I heard about how cement seems to crack under high temperatures - elearning.just.edu.jo/jjce/issues/paper.php?p=117.pdfso I've decided to use plaster instead, as I've heard that plaster was used years ago to fireproof homes. All the best with your pizza business! |
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Post by Deleted on Jun 19, 2012 3:19:43 GMT -8
deliamsSilica (quartz) sands and olivine are used as refractory (molding) sand. Any sand with clay as binder used to cast iron will do it, as it has to resists at least 1200°C. refractory sand is fine grained. But generaly any fine grained silica sand can be used. The pizza oven is on the line of teaching fishing instead of giving fish every day.
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Post by Deleted on Jul 9, 2012 5:15:17 GMT -8
The teaching fishing approach has worked nicely so far.
The income generated with the oven is above-average for a woman, even for a man, in this area.
My sister in law has worked as a cook in an Arab country for many years.
My mother in law is over seventy now, which is quite old in a country
with virtually no health care.
Amazingly she has had all her teeth till seventy.
Signs of old age have showed up and thus my wife has asked her sister to care for
the mother at our home.
We would have eighter to support her completely or give her means to make enough money for herself and her children at our home, while still leaving enough time for caring.
Making own money is a lot better anyway.
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dvawolk
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Post by dvawolk on Jan 13, 2013 3:29:26 GMT -8
Silica (quartz) sands and olivine are used as refractory (molding) sand. Any sand with clay as binder used to cast iron will do it, as it has to resists at least 1200°C. refractory sand is fine grained. Karl, hi! What would be the best grain of quartz sand to be used with clay? And pizza rocket stove is woderfull. I made a small masonry one but it is a wood eater :-) And waiting to heat it is another story?  I am inspired with yours! Maybe this year the changes will come... :-) Klemen |
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Post by Deleted on Jan 13, 2013 4:04:29 GMT -8
Karl, hi! What would be the best grain of quartz sand to be used with clay? That depends on the purpose. With fine grained crushed sand it will be more workable. A mixture with fine and coarse sand will be less workable but give a better thermal mass. For a pizza stove I would prever fine grained sand. |
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dvawolk
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Post by dvawolk on Jan 13, 2013 4:12:53 GMT -8
Ok, but what does really fall under fine grained sand? 2mm? More? Less?
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Post by Deleted on Jan 13, 2013 5:04:49 GMT -8
Ok, but what does really fall under fine grained sand? 2mm? More? Less? Around 0,1 mm. Fine sand is defined as ranging from 125–250 µm 0.0049–0.010 in . |
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dvawolk
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Post by dvawolk on Jan 13, 2013 5:52:33 GMT -8
Thanks for this info. With my conclusion i would bi very wrong...
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Post by Deleted on Mar 5, 2013 10:15:05 GMT -8
I am just back from a one month visit at our home on the Philippines.
Because of a large tangle of straw only poorly mixed with clay a large crack
had emerged above the door of the pizza stove.
An annoying aspect of the asian mentality is people will happily tell you that they
have understood everything even if it was going in in one ear and out of the other
without even touching the brain.
The helper did not have used the mix I had told him.
Last time in April it was just to hot to watch the work closely.
As I have tried to fix the stove I had noticed that most of the dome had turned into
a whitish powdery mess.
Fixing it was impossible, thus I had to rebuild the dome.
No such problems with the rocket core build by myself,
which has been burned to ceramic more than two inch deep.
This time I have used sand as a form.
Due to the season no straw was available, as things are burned immediately after harvest.
Thus the oven needs more time to get hot.
To compensate this a bit I have moved the exhaust to the left of the door as low as
possible.
January and February are the coolest time on the Philippines.
Temperature can drop to 20°C overnight and the days are not very hot too.
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dvawolk
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Post by dvawolk on Mar 8, 2013 23:50:29 GMT -8
.... Temperature can drop to 20°C overnight and the days are not very hot too. Oh, it is nice to know that the days are not very hot, too :-) |
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Post by stephenson1 on Feb 6, 2014 4:06:16 GMT -8
A smaller 110mm rocket for cooking, not wort an own thread. Hi Karl. Can you give any more specifics about this little rocket cooker? Is it an insulative clay? Diameters and lengths etc? It looks like a top feed with a front plug for ash cleanout. I'd like to explore the design with some middle school students. I have a decent sized kiln I could use to fire. Thanks, Mark |
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Post by Deleted on Feb 6, 2014 5:59:59 GMT -8
Can you give any more specifics about this little rocket cooker? Is it an insulative clay? Diameters and lengths etc? It looks like a top feed with a front plug for ash cleanout. The stove is build around 110 mm tubes like in the following picture. donkey32.proboards.com/attachment/download/273The dimensions are following the recomendations. The local red burning clay has a huge schrinkage. Mixed with toilet paper, wood dust, straw and about 10% portland cement to prevent schrinking. This little one is a lot more efficient. donkey32.proboards.com/thread/738/small-cooking-stove-big-families |
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Your pizza oven looks lovely, you did a neat job fitting it into the concrete. I'm experimenting with fire clay and concrete mix with straw and sodium silicate after I noticed a refractory cement mix is being used in South American rocket stoves. I shall pass your mail on to Jed Guinto.