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Post by branja on Jan 16, 2018 8:03:23 GMT -8
Thank you for the excellent info on your mix and experiment. I am looking forward to hearing how your sample performs after it is fully cured! One question: Are you seeing much physical evidence of dissolution of the sweet PDZ granules at that lye concentration? Big chunks becoming smaller? Since you and I are the only ones using that particular Clinoptilolite zeolite product at the moment, me with the power and you with the granular, I'm looking for your experience with that. Grains not dissolving all the way apparently does not prohibit success at Geopolymerization and can be due to natural inclusions of less easily dissolved, or non-dissolvable minerals according to Karl. I had some interesting initial results with the sweet PDZ/lye mix. My long slender mold I treated differently. I left it covered in plastic cling wrap overnight. Then the next morning I placed it in a warm spot next to my wood stove. Then later in the day when I could see moisture collecting under the cling wrap I pulled it off so it could start drying. I have not seen any efflorescence. However, I shaped some of the leftover material into pucks but did not cover them or put them in a warm place. They have developed efflorescence over the entire surface. So I am having thoughts that maybe I should try to somehow warm the overall core mold after I cast clay around it. I'm imagining an insulated box with some light bulbs inside it. One study called "Effect of Curing Profile on Kaolin-based Geopolymers" indicated that a 3 day curing at 60C was ideal based on their test results. The sweet PDZ granules did not seem to dissolve. Just another thouth  Need say "no efflorescence" ,it is bad mojo It will turn up when you least expect it,on day 39 or something. Just a bit of humor,don't take it to the heart. But serious about the "white devil" |
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Post by etownandrew on Jan 16, 2018 12:56:55 GMT -8
As you are finding, it is a balancing act between reactivity of mixture, moisture levels, grog/aggregate and time or energy applied to curing. I can't speak specifically to the zeolite mixture you are playing with as I haven't found zeolite available locally. The amount of shrinkage you are experiencing with the current mixture can be reduced by preventing moisture loss till more polymerization has occurred. Till you have the moisture loss under control don't add additional heat, the uncoated wood is probably wicking away a lot more moisture than you'd expect and the additional heat accelerating that. This will of course will require more time and patience, less moisture to start with will likely produce satisfactory results sooner. This sounds like good input. So my next test may be to seal the wood mold surfaces and leave the clay covered with plastic for several days to allow for more polymerization to occur. I don't really need multiple parts out of this same mold but the length of it helps me measure the overall shrinkage easier. |
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Post by etownandrew on Feb 3, 2018 8:06:26 GMT -8
I tried a couple more tests to try and reduce shrinkage. This 30" long sample shown below was my most successful and had 5% fiber, 10% binder, and 85% backyard clay of unknown composition. I sealed the wood form and also left it covered in plastic for 6 days. At around day 2 or 3 it had developed the cracks shown below. The picture was taken at the 6-day point after removing the covering plastic. It did get noticeably stiffer and so I assume it had formed a geopolymer. I'm going to mix up a couple more test batches today. I'm leaning toward one with 10% fiber and the second 20% fiber. I'm also considering adding some sand as a filler. I want to work out the least amount of filler needed to maximize the insulative properties.   |
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Post by smartliketruck on Feb 3, 2018 13:42:35 GMT -8
Did you happen to get a wet starting weight in the mold so you can monitor water loss?
When you make the final mix of binder, filler and aggregates/fibers are you adding much water to get the viscosity you want?
If you are adding water to the final mix, you may want to consider hydrating your clay filler to that consistency several days ahead of time.
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Post by etownandrew on Feb 5, 2018 9:33:30 GMT -8
I did not get a wet starting weight. That is a good thought to see if I was losing water. It happens that I keep my backyard clay wet and so it had been sitting in a covered tub with enough water to keep it moist for weeks. During the final mixing, I include some dry fiber until the clay gets to be too dry and hard to blend. I ended up making a 10% fiber and 20% fiber test mix. The 10% fiber amount felt good and was well coated with clay. The 20% mix was a ridiculous amount of fiber and it didn't feel like I had enough clay to coat all the fiber.
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Post by etownandrew on Feb 13, 2018 15:44:33 GMT -8
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Post by pigbuttons on Feb 13, 2018 19:39:25 GMT -8
That looks awesome for backyard clay. Way to go. Thanks for sharing.
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Post by firewatcher on May 11, 2018 14:56:36 GMT -8
I tried 10% fiber and 20% fiber. The 10% fiber shrank 2% when drying. The pictures below are of the 10% sample. It turned out well other than the 2% shrinkage from drying. The 20% fiber did not measurably shrink. I don't think it had a good clay covering on the sample. After being burnt in a fire and also when a sample was put in an oven the final result was very weak and I could easily put a finger nail into it. ![]()   Have you tried any "breaking" tests with your test pieces? One of the issues that I've had with mixes that I've tried is that they are too weak...which I've been told is do to lack of geopolymerization. I've mixed up several test pucks in the last month or so (using zeolite)...only the last of which has used mineral wool (only 3%). This test piece had significant shrinkage (I haven't measured it yet to report on a % amount), but thus far has not suffered any cracks (total size of the piece is only something like 5 inches x 3 inches x 0.75 inches thick. I'm going through the curing process now, hoping to test the latest mix's thermal conductivity (reverse side temperature measurement) and break strength (trying to break it by hand). I'll share my results when full curing can be performed. |
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Post by etownandrew on Jun 28, 2018 8:23:16 GMT -8
I have not tried measured break tests. So far my evaluation was mostly a subjective feel of the finished material by squeezing and trying to put my fingernail into it. I want to get back into this and test a piece with some sand also added to try and further reduce the shrinkage. 2% is not bad but I would still need to allow for it in the design.
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Post by gadget on Jun 28, 2018 12:22:34 GMT -8
It can be difficult getting even drying in a wood mold. Uneven drying = cracks
-Gadget
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Need say "no efflorescence" ,it is bad mojo 
