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Post by Deleted on Dec 21, 2017 12:04:57 GMT -8
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Post by briank on Dec 21, 2017 12:58:23 GMT -8
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Post by woodburner on Dec 27, 2017 12:22:24 GMT -8
Geopolymers could be interesting, but for those who don’t know the chemical, lye is sodium hydroxide and is a very corrosive alkali.
BE VERY CAREFUL!!! it could spoil your day.
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Post by Deleted on Dec 29, 2017 4:31:21 GMT -8
Geopolymers could be interesting, but for those who don’t know the chemical, lye is sodium hydroxide and is a very corrosive alkali. BE VERY CAREFUL!!! it could spoil your day. Weak acids combined with micronized basic stone flour like nepheline syenite or basalt can be used as geopolymeric binder as well. Citric acid alone can make it sufficiently water resistand to pass the submerged water test. Applying the extreme chemical attack similar to a LTGS binder can improve the outcome. Additional phosphoric acid gives extreme water resistance. Phosphoric acid alone does not nearly perform as well, Nepheline syenite is relatively cheap and available from virtually any pottery supply. |
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Post by briank on Dec 29, 2017 17:58:32 GMT -8
I think we still need to see photos of a batch box rocket build as well as long term results for spans (firebox roofs, long sections of risers) of refractory geopolymers and successful overall builds before they can be recommended.
There’s lots of photographic and video evidence of successful batch box rocket builds available online and going back years now, using firebrick and ceramic fiber boards.
I have yet to see such documentation regarding refractory geopolymers. This seems to still be in the early conceptual and strictly experimental stage. One can’t tell people to build these to contain over 2000•F fires in the middle of their living rooms until one can document successful builds and give very specific instructions for the recipes.
People need to understand this is still strictly experimental and untested for any long term batch box rocket builds.
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Post by Deleted on Dec 29, 2017 19:08:53 GMT -8
The NASA has used geopolymers for much higher temperatures many years ago.
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Post by wiscojames on Dec 29, 2017 19:49:53 GMT -8
Do you have any theory why it has not gained acceptance if, indeed, they are a cheap, high performance class of refractories? My excitement is mostly for their potential for a low tech, local solution, insofar as one can use local clay as the main ingredient, and the other ingredients are cheap and easily sourced.
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Post by briank on Dec 29, 2017 22:38:43 GMT -8
The NASA has used geopolymers for much higher temperatures many years ago. Keep experimenting and documenting! But just refrain from telling folks to use this technology at its current level of development inside their homes until some proven documentation exists for diy builds for this specific application. Diy home rocket heater builders ain’t NASA engineers. I agree that the potential to develop a low tech, cheap and local solution with this technology is stupendous! I’d have no problem at present recommending back yard or shop builds based on these techniques. However one would be irresponsible at best encouraging a batch box rocket mass heater build inside someone’s home based on the level of development of this diy technology, techniques and specific instructions/recipes developed to date. (I come from a medical background, so the idea of liability even from casual advice is always in the back of my mind, unfortunately.) |
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Post by esbjornaneer on Dec 30, 2017 1:10:25 GMT -8
So Brian, when does something that is "experimental with a potential" become acceptable for promotion into the public? Should we already be testing/contemplating/working on DSR builds when Peter is still testing? The BBR is how many years old since development started? How many years has Karl been developing the Geopolymers he is recommending?
I know you are not stating that all should have a DSR in a barrel like you built. It is my opinion however that when new suggestions come up, be it the DSR, ceramic fiber board, or LTGS it has to be done by several to see how it turns out. It is not helped by putting a damper on it, test it yourself instead! Then if you have got the material right and a 'long section' fails: report that back!
I am not interested in using shop bought pourable refractory concrete as I have not got the vibrating table and can not get the mix at a reasonable price but I am not telling others not to use it. Do you see my point?
I am building a DSR with a friend that at first would not accept that it would draw nor have the rocket sound. It was only doing a dry stack of bricks that convinced her that the core could. She is still not convinced that it will work with a bell and a chimney. We are putting that together for her to see that it will work. Some people say that it is only when seeing that one can believe, others state that it is when believing that one sees.
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Post by briank on Dec 30, 2017 4:30:23 GMT -8
There’s a big difference between building a new configuration of a rocket heater using proven materials and techniques based on well established principles, and even recommending others do so, versus recommending others build a complete home rocket based on diy refractory materials for which diy techniques and recipes are not well established.
I’m just raising a caution, that’s all. With a recommendation for a DSR configuration of a barrel stove, the worst that could happen is a dirty burning inefficient rocket heater in a barrel. No catastrophic failure could occur due to the use of these materials.
In this thread it’s being proposed to use diy LTGS materials in building a home rocket, instead of well documented and utilized commercial refractory products. There is serious liability in that recommendation should diy LTGS polymers fail and a home burns down due to insufficient explanation and documentation of recipes, technique and precautions.
Peter’s recommendations are based on years of hard work, experimentation with real world designs and established refractory materials, testing with combustion analyzers, etc. Same with Matt’s and others. So there’s a robust body of evidence upon which to base a recommendation to build these units for home use, and should a failure occur, one can point to this robust body of evidence regarding specifically prior real world Rocket Heater builds to justify their recommendation. This robust body of evidence simply doesn’t exist yet regarding LTGS polymers and it would be premature to promote their use in actual diy home builds by newbies and lurkers, to the point that it opens one to serious liability should one fail.
I’ve said my piece here and raised what I feel is a necessary precaution. Carry on.
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Post by patamos on Dec 31, 2017 13:18:39 GMT -8
Thought i'd chirp in to say that i am hopeful the heatedness of this debate will rouse us all into new perceptions. In case some are not aware, Karl has come and gone a few times on this forum, so his actual post count it way up there over 1000. And the bulk of those have been providing useful scientific information to anyone who asks. His understanding of chemistry is way beyond mine, but by all my means of inferential cross-referencing, he ought not be confused with an armchair misinformist... I've gotten into ceramic fibre board with caution because of the respiratory threats. And i am presently sourcing out calcium silicate board to give that a try. For now i am build top spanning decks with 1" thick kiln shelves. I've yet to make LGTS geopolymers, but having experimented extensively with various DIY clay, sand, perlite, vermiculite, (non/)organic fiber, and socium silicate combos... and having seen a few of my cast refractory efforts degrade due to poor vibrating and/or over watering, i feel myself heading in the LGTS direction. Maybe the thread is already out there, but if someone can point towards a simple brick-making recipe I will do up a test sample and fire up the tiger torch  |
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Post by briank on Dec 31, 2017 19:25:28 GMT -8
Maybe the thread is already out there, but if someone can point towards a simple brick-making recipe I will do up a test sample and fire up the tiger torch I am not at all opposed to geopolymers, which hold incredible promise, and I will happily promote them once a simple brick making recipe and technique that works every time diyers try them under reasonably controlled conditions is developed, but that’s the rub. To my knowledge, one simple, clear, concise and straightforward recipe, including specific materials, exact amounts and techniques that work every time the average builder tries it, has yet to be formulated and adequately communicated. Based on recent private communication, I have reason to believe that this is close on the horizon, but we’re just not there yet. It’s being boiled down into something cohesive and succinct from multiple threads and websites, but it’s not “ripe” yet. |
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Post by patamos on Dec 31, 2017 19:50:09 GMT -8
Agreed!
And i too am looking forward to it.
Maybe the first trial application can be in the firebox ceiling. High thermal stresses with low mechanical stresses, but readily replaceable with forethought in the construction.
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Post by briank on Dec 31, 2017 19:55:04 GMT -8
Maybe the first trial application can be in the firebox ceiling. High thermal stresses with low mechanical stresses, but readily replaceable with forethought in the construction. That will definitely prove the concept, if it holds up long term. At present I’m using 2” ceramic fiber board for the roof of the firebox and other than the health considerations it seems pretty ideal. |
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Post by Deleted on Jan 1, 2018 6:09:27 GMT -8
A simple, clear, concise and straightforward recipe for bricks, including specific materials, exact amounts and techniques that work every time the average builder tries it, has been formulated and patented by professor Davidovitz a long time ago. The patent has expired and is in the public domain since many years. As the patent had expired professor Davidovitz has published a PDF paper describing the technique in detail. www.geopolymer.org/fichiers_pdf/ltgs.pdfMaybe one can find the original french patent and translate it. The technique was only patented for laterite clay which is a red clay with very high iron content, however the technique works not only for this kind of clay but for any alumino silicate clay and for any kind of finely divided alumino silicate. |
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