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Post by firewatcher on Sept 10, 2016 10:37:50 GMT -8
Looks quite good. If the pozzolan is fine enough such a mixture can become pretty hard and strong. Could you do a reverse side test ? At the moment I am trying to recreate a recipe for bricks or stamp mass similar to the recipe for LTGS bricks.
I'm not sure what happened...the first recipe that i used seemed to work well. Really only small adjustments were made from the recipe that I originally used.
Karl, if you don't mind, when you get a chance could you please have a look at what might have caused the (percieved) ill effect on the latest mix.
First recipe...after a 20 minute opposite side test (MAPP gas torch) I was able to place my hand on the opposite side of the puck (this was a 2 inch puck):
200 g powder perlite
70 g fire clay
800 g slag
1.5 cups 1.5L water to 1000g solids waterglass (mixed lye and silica gel)
100 g hydrated lime
Latest recipe...after a 10 minute opposite side test (MAPP gas torch) the opposite side was very hot to touch (this was a 1 inch puck):
100 g powder perlite
35 g fire clay
400 g slag
0.75 cups 1L water 330g powder waterglass (Red Devil sodium metasilicate)
13.5 g hydrated lime (10% of pozzolan + clay)
5 g lye (for better curing 5% - 10% of pozzolan)
Any ideas as to what might have happened? Most of the changes were just scaling down from a 2 inch puck to a 1 inch puck (same 5 inch diameter). Obviously the waterglass composition changed as well as the concentration...and the amount of hydrated lime as well as the addition of the lye changed to combat the cracking that I experienced in the first recipe.
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Deleted
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Post by Deleted on Sept 10, 2016 12:51:56 GMT -8
The 2" puck was not fired before the test.
Dehydration takes energy.
The 1" puck had already lost most of the hydrates.
If one side is heated by a 3000℃ flame,
then 10 minutes to get over about 75℃ at the other
is a very good value.
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Post by firewatcher on Sept 10, 2016 13:04:39 GMT -8
The 2" puck was not fired before the test. Dehydration takes energy. The 1" puck had already lost most of the hydrates. If one side is heated by a 3000℃ flame, then 10 minutes to get over about 75℃ at the other is a very good value. I'll have to see if i can find an inexpensive IR thermometer to use so that i can provide more quantitative information on the opposite side tests. Do you have any ideas as to why i got the "bubble" in each of the pucks? This seems to be the same area where some liquid pooled up on top of each of the castings when pouring them. It appeared to be gone before i "fired" the pucks...but perhaps it just started to reabsorb back into the material. |
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Deleted
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Post by Deleted on Sept 10, 2016 13:21:22 GMT -8
I have no idea about the bubble.
Have not experienced one.
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Post by firewatcher on Sept 11, 2016 11:11:42 GMT -8
Maybe there's something wrong with my process of mixing together the components? I haven't been able to duplicate the "success" that i had with the 50 mm thick puck, either on opposite side test nor in strength. The two differences are the much more highly concentrated waterglass (1000g solids to 1.5L water) and 90% more hydrated lime. I just poured another test brick using the "adjusted" recipe. I'm going let it cure at ambient temp for a week and then "fire" it. Hopefully different curing methods will have a positive effect. We'll see! :confused:  |
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Post by firewatcher on Sept 11, 2016 15:04:46 GMT -8
Yes from a supplier. Look for suppliers that supply soap fabric softener making factories. The place I found buys sodium silicate lumps from India and then they process it for their clients. Hi Lawry, I've been meaning to ask, how did your second mold turn out? Any pictures to share? Results from testing it out? |
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Post by firewatcher on Sept 11, 2016 18:10:08 GMT -8
Karl,
You had mentioned previously in your acid activated geopolymer thread the addition of aluminum to the mix by dissolving aluminum in a lye solution.
Is this in effect adding "alumina" to the mix?
Is it correct to say that the more "alumina" a refractory mix has, the more insulative it becomes?
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lawry
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Post by lawry on Sept 11, 2016 22:05:46 GMT -8
Hi Lawry, I've been meaning to ask, how did your second mold turn out? Any pictures to share? Results from testing it out? Hi firewatcher. Please excuse my absence. I forgot that I didn't update on this thread. I updated Karl on another thread.... I took a small break after the mold failed to release. I decided to get the molds made professionally. So that will take a while till I save up enough money. In the meantime I have a large TLUD project that is keeping me busy. I m thinking of making usable bricks though. These shouldn't get stuck so badly. I will update when I have made some. |
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lawry
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Post by lawry on Sept 11, 2016 23:19:41 GMT -8
Do you have any ideas as to why i got the "bubble" in each of the pucks? This seems to be the same area where some liquid pooled up on top of each of the castings when pouring them. It appeared to be gone before i "fired" the pucks...but perhaps it just started to reabsorb back into the material. I have had the bubble as well. You are right it forms when the mixture is more wet. Where the liquids pool up. I thought it was normal. In the Davidovits of how to mix geopolymer, they mentioned that there is a weaker thin layer that may form at the top and they remove it mechanically. I just thought of the bubble as something similar. Listen at 3:25 youtu.be/PQZx7PSol1E |
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Post by Deleted on Sept 12, 2016 4:10:51 GMT -8
Karl, You had mentioned previously in your acid activated geopolymer thread the addition of aluminum to the mix by dissolving aluminum in a lye solution. Is this in effect adding "alumina" to the mix? Is it correct to say that the more "alumina" a refractory mix has, the more insulative it becomes? Liquids are more reactive than finely devided particles. The sodium aluminate reacts quickly with the waterglass. Among other things this is also responsible for the high reactivity of acid treated clays. The acid extracts metal ions from the clay. The high liquid demand of bentonite causes a very high silica/alumina ratio. Additional aluminium lowers this ratio. Alumina has a lower heat capacity than silica. In materials which cannot conduct electricity and also are not very hard heat capacity and conductivity have a close relation, thus geopolymers with high alumina content have a lower conductivity. Hovever due to the high porosity of geopolymers the difference is not big. |
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Post by firewatcher on Sept 12, 2016 4:32:51 GMT -8
I have had the bubble as well. You are right it forms when the mixture is more wet. Where the liquids pool up. I thought it was normal. In the Davidovits of how to mix geopolymer, they mentioned that there is a weaker thin layer that may form at the top and they remove it mechanically. I just thought of the bubble as something similar. Listen at 3:25 youtu.be/PQZx7PSol1ELawry, thanks for sharing the video...i had not seen that. Sorry to hear about having to wait on the molds. I hope that it's not too long before you can get back to it. I'm guessing that you have a "recipe" in mind for your refractory? Could you share? If i have the components available, I would like to test it as well. I'm still testing and re-testing several myself before deciding. Until yesterday, I hadn't tested anything larger than a 5 inch puck. Karl keeps coming up with new ones for me to try (and tweaks to make them better)  which is keeping me busy...I appreciate the input. |
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Post by firewatcher on Sept 12, 2016 5:18:57 GMT -8
Karl, You had mentioned previously in your acid activated geopolymer thread the addition of aluminum to the mix by dissolving aluminum in a lye solution. Is this in effect adding "alumina" to the mix? Is it correct to say that the more "alumina" a refractory mix has, the more insulative it becomes? Liquids are more reactive than finely devided particles. The sodium aluminate reacts quickly with the waterglass. Among other things this is also responsible for the high reactivity of acid treated clays. The acid extracts metal ions from the clay. The high liquid demand of bentonite causes a very high silica/alumina ratio. Additional aluminium lowers this ratio. Alumina has a lower heat capacity than silica. In materials which cannot conduct electricity and also are not very hard heat capacity and conductivity have a close relation, thus geopolymers with high alumina content have a lower conductivity. Hovever due to the high porosity of geopolymers the difference is not big. Thanks Karl, this is another "good to know" as chemistry is not a strong point for me and most of the research papers are using language which is sometimes difficult for me to follow. I don't know what kind of alumina content the "fire clay" that I buy has, and I was considering using your suggestion of dissolving aluminum in lye solution to see how much effect it had on thermal conductivity of one of the better working mixes that I've used. I wonder how much effect it would have though due to such small amounts of the clay being used. In the small batch recipe that I'm thinking of, I only use 35g of the "fire clay" with 100g pozzolan (perlite powder) 1 cup liquid waterglass (330g solids to 1L water) 400g slag and 13g hydrated lime and 5g lye So as not to "waste" aluminum, would there be an ideal amount to use? Most likely, I'd create a solution with the 5g of lye used in the recipe already...i think there must be a saturation point of the solution though limiting the amount of aluminum able to be dissolved. Lastly, do you have comments on whether beer cans could be used or aluminum foil? Obviously I can test, but I'm all for avoiding what you may already know not to work well. |
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Post by Deleted on Sept 12, 2016 6:24:12 GMT -8
Commercially sold fireclays have 20%-40% alumina,
usually close to 30%.
Untreated clay is chemically quite inactive.
In the mixture the clay serves mainly as a thickener.
Clays are thixotropic, which means slurries become more liquid
if stirred or vibrated and unmovable at rest, which prevents segregation.
You could activate the clay with acid.
Whet activation of clays with organic acids works like a charm.
This possibility is actually extremely obvious catching your eyes,
I've always wondered why nobody has done that.
Guess I could have got a patent on it.
For health reasons I could not accompany my wife and son on the visit
of our home on the Philippines.
For five weeks I was alone, very bored with lots of free time
and no wife complaining about the dirt involved with my experiments.
Thus I decided to give acid activation a try.
Acid can extract metal ions from perlite or zeolite
and increase the reactivity in other ways as well.
As clays have very small particles acid activated clay is superior to perlite or zeolite.
If you want to build a big one or more than one stove you could get 100lb clay for acid activation from Rovin Ceramics Inc.
Per lb for 100-499lb:
Ball Clay, OM4 $0.24
Kaolin, 6 Tile $0.47
Ball clays have a higher water demand than kaolin.
You can mix the clay with the pozzolan you already have.
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Post by firewatcher on Sept 12, 2016 7:19:15 GMT -8
Karl,
Thanks once again for all of the helpful information. Before spending any more money on supplies that are taking up increasing amounts of space in my garage, I'll try activating some of the "fire clay" that i have currently and making some test pucks with my current "best working" recipe.
I have the same issue with the wife commenting on me spending so much time on this project and messes in the garage! With kids back in school now, it's going to become more difficult to find the time to work on this, but my goal was to decide on a good refractory recipe by the end of October. Not sure if that's going to happen or not.
If I can make a decision by then, and enough money is available, I would like to cast a test j-tube before it gets too cold so that i can test burn over the winter (burn performance/freeze-thaw compatability/etc).
I already have a 5 inch j-tube mold made up...just need to modify it for 1 inch thickness, as i had previously planned on molding with 2 inch thickness. The modification shouldn't take much time at all though.
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lawry
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Post by lawry on Sept 12, 2016 7:32:34 GMT -8
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which is keeping me busy...I appreciate the input.