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Post by firewatcher on Sept 21, 2016 9:25:58 GMT -8
All the LTGS mixtures I have tested so far cheap oddinary vinegar with 5% acetic acid content was used. For 5% add winegar with the weight of the clay, for 2.5% only half the vinegar and fill it up with water if needed. I am testing things for practical use and try to keep (my) costs low, I'm a little unclear. So that I understand correctly then, if a mix calls for 5% acid added to 100g of clay this would be 5g of acid. In order to get 5g of acid, I would need approximately 1L of vinegar. The way that i understand your description above, it sounds like you're saying to add 5% weight of vinegar by weight of the clay? For example, add 5g of vinegar to 100g of clay? I must be misunderstanding...
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Post by Deleted on Sept 21, 2016 9:50:05 GMT -8
1 liter is about 1000g thus 1 liter vinegar with 5% acetic acid contains 50g acetic acid. For 5g acetic acid you need 100ml respectively 100g vinegar. For 100g clay activated with 5% add 100g vinegar. For 100g clay activated with 2.5% add 50g vinegar.
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Post by firewatcher on Sept 21, 2016 9:55:03 GMT -8
1 liter is about 1000g thus 1 liter vinegar with 5% acetic acid contains 50g acetic acid. For 5g acetic acid you need 100ml respectively 100g vinegar. For 100g clay activated with 5% add 100g vinegar. For 100g clay activated with 2.5% add 50g vinegar. Sorry...yes...I moved the decimal place. Thanks for the confirmation.
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Post by firewatcher on Sept 22, 2016 7:36:28 GMT -8
Yes, 10% LTGS means 5% clay +5% lye + another 90% clay. You can mix vinegar with water for lower percentages. The only difference to the solid form is that the vinegar contains impurities. I have not noticed any negative effects from the impurities. You could test your fire clay. If it is normal clay and not some grinded mudstone it should work. @karl, I bought some citric acid yesterday and put together an excel spreadsheet which does the quick calculations for me based on 3 inputs for proportions of the mix. I'm going to scale down the 10% LTGS recipe (to use less materials) and give your suggestion of 30% slag a try. I'll activate the clay today and keep you updated on my progress.
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Post by Deleted on Sept 22, 2016 8:15:44 GMT -8
I have prepared a 20% LTGS mixture in the usual way and mixed it 1/1 with fine slag sand, with just enough water for a thick castable paste only flowable under beating or vibration. The result with a dry density of 1.46 got much stronger than the mixtures with higher aggregate load, stronger than concrete with a similar density, but far away from the strength of a 10% ram mixture without aggregates.
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Post by firewatcher on Sept 22, 2016 8:36:44 GMT -8
Karl,
How are you determining strength of the material to compare from one mix to another? Just wondering if/how I could compare to your results. Bonus question, what kind of clay are you using?
Because it's what i have on hand currently, I'll be using the "fire clay" of unknown composition to see if it works. As a side note, I buy it in 50 pound bags from a construction supply shop. If i buy 100 pounds of the kaolin clay from rovin, i'll actually be paying slightly less than what i currently pay for the "fire clay".
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Post by Deleted on Sept 22, 2016 10:18:35 GMT -8
By scratching it with a knife, trying to break it with my hands, using a hammer to cut off a small piece.
Not very precise.
It is a cheap white plastic stoneware clay with about 26% alumina. 1kg = 0,83€ ~ $0,93 25kg = 0,29€/kg ~ $0,33/kg
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Post by firewatcher on Sept 22, 2016 14:46:23 GMT -8
@karl, Maybe you were right and my "fire clay" is "ground mud stone". I never paid much attention to it...just added to the mixes that i was making and didn't give it another thought. I just finished activating the clay so that I could mix up a test batch tomorrow. This is how it looks straight from the bag.
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Post by firewatcher on Sept 23, 2016 13:24:44 GMT -8
Jusy finished casting the 10% LTGS mixture with 30% aggregate. The mix was was thick enough that I was able to remove the mold immediately. I did mess up though (should have added the lye to the binder and waited a few hours, but I didn't go back and check the mixing directions before putting all of the mix together in my excitement). So we'll see how it turns out after drying for some time...and then attemptimg to temperature cure The "plate" is approximately a 9 inch square (23 cm square) about 1 inch (25mm) thick.
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Post by firewatcher on Oct 2, 2016 8:22:46 GMT -8
I was finally able to "camp fire" cure my LTGS brick... Just as a remimder, this was a 10% binder mix with 30% slag. I don't know if it made a difference or not either, but i did make a mistake when mixing...when adding the lye, instead of mixing it with the binder portion and letting it rest for several hours, I had mixed all of the clay together and added the lye. Since I had already messed up the process, i just molded the mix immediately. The surface was fairly hard and somewhat wear resistant but I was able to scratch off material in various places on the brick with my fingernail and in other places I could not. I don't know whether to just give up on this fire clay that I've been using or if the fire temperature just wasn't high enough, or if not following the process caused the poor results. The coals that the brick was in font of for 2.5 hours were hotter than my thermometer could read (1000F) so I would have thought that the temp was fine.
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Post by Deleted on Oct 2, 2016 9:12:18 GMT -8
With a properly made LTGS binder the result would be much better. Though your clay with unknown properties plays a role too. Curing at 75°C was enough for me to get a water resitant and hard result.
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Post by firewatcher on Oct 2, 2016 9:47:37 GMT -8
With a properly made LTGS binder the result would be much better. Though your clay with unknown properties plays a role too. Curing at 75°C was enough for me to get a water resitant and hard result. I'll give it another try using the correct method this time...
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Post by firewatcher on Oct 2, 2016 12:12:03 GMT -8
I couldn't resist breaking this brick...had to see how strong or weak it was...here's the result: A few points of notice: - it was very difficult to break - it appears that there was some separation in the mix (darker center and lighter colored top and bottom) - It appears that while moulding, there were air pockets left between layers. Some were quite large - the inner darker area was very hard and scratch resistant, much like the surfaces of my other geopolymer test bricks.
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Post by firewatcher on Oct 2, 2016 13:15:25 GMT -8
@karl, I was mixing up my next batch of clay for another try at an LTGS brick and while cleaning off the paddle mixer, found this in the bottom of the bucket... I know that there's no way to know what it is...but if there's enough of this stuff in my fire clay, could it be contributing to my lack of success as well do you think with regards to strength?
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Post by Deleted on Oct 3, 2016 2:58:38 GMT -8
Without knowing what it is I cannot say anything.
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