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Post by coastalrocketeer on Mar 4, 2018 13:22:41 GMT -8
With high alumina clays for geopolymerization, one will always be on the safe side. One could "Bet the Farm" on virtually any geopolymer made from high alumina materials. By the way, has anyone heard from karl lately?? Karl was ill for a couple of weeks, but has posted on the forum in the last few days, and let me know via PM that he has received my package with the sample of SweetPDZ zeolite "horse stall freshener" for testing, within the last week. Lets all send some healing intentions his way, as I know I, and likely others, have missed his presence and help. |
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Post by Deleted on Mar 4, 2018 15:20:21 GMT -8
Another question though. How 'durable' do you need your product to be? Most of mine to date can all be carved quite easily with a sharp knife even after being heated to 700*+ F, much like soapstone. A chain cannot be stronger than the weakest link, therefore I have always strictly advised against the use of vermiculite, perlite and the like as aggregate. Low density comes at a price too. A density below about 1.3 g/cm3 indicates more than 50% air in the volume. Alkaline aluminosilicates have typicaly a density around 2.5-2.7 g/cm3 with a hardness around 6-7. A Knife Blade has about 5.5. The three samples in the following paper are relatively dense, but have nevertheless a quite low thermal conductivity. The Potential of Geopolymer as High Quality Refractory www.researchgate.net/publication/291953832_The_Potential_of_Geopolymer_as_High_Quality_Refractory |
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Post by sksshel on Mar 5, 2018 6:52:25 GMT -8
I've captured some of Karl's notes and updated them into the second post on this thread.
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Post by sksshel on Mar 11, 2018 7:02:46 GMT -8
I've updated my original post with the cured product volume.
The product is by far the hardest that I have tested. No crumbling around the outside like what I've seen in my other recipes. I will conduct fire and water testing somewhere around the beginning of April.
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Post by Deleted on Mar 12, 2018 6:37:31 GMT -8
I have calculated the chemical reactions for Kansas City #1
Molar mass:
Al2Si2O5(OH)4 ~ 258.2 g/mol
CaO ~ 56.1 g/mol
Ca3(PO4)2 ~ 310.2 g/mol
H3PO4 ~ 98 g/mol
KH2PO4 ~ 136.1 g/mol
K2HPO4 ~ 174.2 g/mol
KAlSiO4 ~ 158.2 g/mol
KOH ~ 56.1 g/mol
Molar mass ratio:
Al2Si2O5(OH)4/KOH ~ 4.6
Ca3(PO4)2/3CaO ~ 5.53
CaO/KH2PO4 ~ 0.412
KAlSiO4/KOH ~ 2.82
KOH/KH2PO4 ~ 0.412
Kaolinite
Chemical Formula: Al2Si2O5(OH)4
Alternative notation Al2Si2O7*2(H2O)
Molecular Weight ~ 258.2 g/mol
Composition:
Al2O3 = 1 mol ~ 102.0g 39.50 %
SiO2 = 2 mol ~ 120.2g 46.55 %
H2O = 2 mol ~ 36.0g 13.95 %
The acidic Monopotassium phosphate reacts to strongly with caustic calcium,
therefore the monopotassium phosphate must be become basic as well
by reacting it with potassium hydroxide.
Monopotassium phosphate + Potassium hydroxide
KH2PO4+KOH = K2HPO4 + H2O
6 K2HPO4 + 3 Ca(OH)2 = Ca3(PO4)2 + 4 K3PO4 + 6 H2O
6 K2HPO4 + 3 CaO*H2O= Ca3(PO4)2 + 4 K3PO4 + 6 H2O alternative notation
4 K3PO4 + 6 CaO = 2 Ca3(PO4)2 + 6 K2O
Molar ratio CaO/KH2PO4 = 1.5
6 K2O + 6 H2O = 12 KOH
6 Al2Si2O5(OH)4 + 12 KOH = 12 KAlSiO4 + 18 H2O
Tricalcium phosphate Ca3(PO4)2 melting point ~ 1670°C / 3038°F
Kalsilite KAlSiO4 melting point~ 1750 °C / 3182 °F
Portland cement (OPC) contains about 64% CaO.
Binder composition by weight:
Monopotassium phosphate KH2PO4 = 1
Potassium hydroxide KOH = 0.42
Calcium oxide = 0.42 * 1.5 = 0.63
Portland cement = 0.63: 0.64 = 0.98 ~ 1
Binder yield ratio
KAlSiO4/KOH ~ 2.82*2 ~ 5.64
Ca3(PO4)2/CaO ~ 1.84
Ca3(PO4)2/OPC ~ 1.84*0.64 ~ 1.18
10% monopotassium phospate
4.2% Potassium hydroxide
6.56% OPC
will yield about
23.6 % KAlSiO4 Kalsilite
7.7 % Ca3(PO4)2 Tricalcium phosphate
Total binding minerals 31.3%
The Molar ratio CaO/KH2PO4 is 1.5 thus the OPC can be increased by 1.5
10% monopotassium phospate
4.2% Potassium hydroxide
10% OPC
will yield about
23.6 % KAlSiO4 Kalsilite
11.8 % Ca3(PO4)2 Tricalcium phosphate
Total binding minerals 35.4%
Those who want to have even cheaper mixtrures may try:
light colored clay with about 27% alumina which would mainly yield leucite
light colored clay with about 20.5% alumina which would mainly yield orthoclase
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Post by sksshel on Mar 12, 2018 7:40:29 GMT -8
Excellent work and insights Karl. Thanks.
The resulting formula with all its components would be:
KOH 6.1g 4.2%
Monopotassium phosphate 14.5g 10.0%
Kaolin 100.0g 68.9%
Portland Cement 14.5g 10.0%
Rockwool fibers 10.0g 6.9%
Total: 145.1g
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Post by sksshel on Mar 12, 2018 8:00:04 GMT -8
Does this mean that the product is roughly 23.6% geopolymer?
From Wikipedia: Definitions of the term geopolymer
For chemists
'...Geopolymers consist of a polymeric Si–O–Al framework, similar to zeolites. The main difference to zeolite is geopolymers are amorphous instead of crystalline. The microstructure of geopolymers on a nanometer scale observed by TEM comprises small aluminosilicate clusters with pores dispersed within a highly porous network. The clusters sizes are between 5 and 10 nanometers.'
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Post by Deleted on Mar 12, 2018 9:40:34 GMT -8
It is a bit more complicated.
This cheap mixture will not result in 100% reacted materials,
but enough to bind the remaining Kaolinite until more of the material can sinter at high temperatures.
And the geopolymeric reaction does not actualy imediately create kalsilite.
The kalsilite will be created once the geopolymer starts to crystallize above 500°C / 932°F
Kalsilite ~ 1750 °C / 3182 °F
Chemical Formula: KAlSiO4
Molecular Weight = 158.16 gm
Potassium 24.72 % K 29.78 % K2O
Aluminum 17.06 % Al 32.23 % Al2O3
Silicon 17.76 % Si 37.99 % SiO2
Oxygen 40.46 % O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Kalsilite contains about 30% K2O
If you substract it (158.6*0.298 ~ 47.1) from the molecular weigth of 158.16 then rest is 111.5 metakaolin.
Kaolinite contains about 14% water thus 111.5:0.86 ~ 129.65.
Kaolin clay contains roughly 2% impurities thus 129.65:0.98 ~ 132.6.
The weight ratio of 2KOH/K2O is (56.1*2)/94.2 ~ 1.2 thus 47.1*1.2 ~ 56,52
56.5 is about 42.6% of 132.6.
Fully reacted kaolin clay requires a huge lot of KOH, which makes it a lot more expensive.
A mixture of light colored clay with about 27% alumina would yield mostly leucite with 218.25 gm
and thus a significantly higher percentage of reacted material, but decreased refractoriness.
and a mixture with 21% alumina would yield mostly orthoclase with 278.33 gm
and thus an even higher percentage of reacted material, but even more decreased refractoriness.
Note: even the 23.6% require elevated temperatures of at least 85°C/ 185°F or many weaks of ambient curing.
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Post by Deleted on Mar 13, 2018 8:05:06 GMT -8
Calcium phosphate can react with kaolinite or kalsilite and form long chains, which fulfill the definition of a polymer.
Ca3(PO4)2 + Al2Si2O5(OH)4 = Ca3(PO4)2*Al2Si2O5(OH)4
Ca3(PO4)2*Al2Si2O5(OH)4 + Ca3(PO4)2 = Ca3(PO4)2*Al2Si2O5(OH)4*Ca3(PO4)2
Ca3(PO4)2*Al2Si2O5(OH)4*Ca3(PO4)2 + Al2Si2O5(OH)4 = Ca3(PO4)2*Al2Si2O5(OH)4*Ca3(PO4)2*Al2Si2O5(OH)4
Ca3(PO4)2*Al2Si2O5(OH)4*Ca3(PO4)2*Al2Si2O5(OH)4*Ca3(PO4)2 = Ca3(PO4)2*Al2Si2O5(OH)4*Ca3(PO4)2*Al2Si2O5(OH)4*Ca3(PO4)2
Ca3(PO4)2 + KAlSiO4 = Ca3(PO4)2*KAlSiO4
Ca3(PO4)2*KAlSiO4 + Ca3(PO4)2 = Ca3(PO4)2*KAlSiO4*Ca3(PO4)2
Ca3(PO4)2*KAlSiO4*Ca3(PO4)2 + KAlSiO4 = Ca3(PO4)2*KAlSiO4*Ca3(PO4)2*KAlSiO4
And so on.
Alternative notations of kalsilite KAlO2SiO2 or KAlO2*SiO2
KAlO2*SiO2 + KAlO2 = KAlO2*SiO2*KAlO2
KAlO2*SiO2*KAlO2 + SiO2 = KAlO2*SiO2*KAlO2*SiO2
KAlO2*SiO2*KAlO2*SiO2 + KAlO2 = KAlO2*SiO2*KAlO2*SiO2*KAlO2
And so on.
Each "*" marks a grain boundary.
Because this can happen in more than one dimension the result will be a three dimensional network.
I hope this makes it clear what a geopolymer is and why they have a low thermal conductivity.
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Post by sksshel on Mar 30, 2018 13:16:04 GMT -8
Here are the results of the temperature testing using a geopolymer piece 7/8" thick. There were NO SIGNS of melting or burning on the surface of the sample. (all Temperatures in Degrees F)  |
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Post by sksshel on Mar 30, 2018 13:35:15 GMT -8
24 Hour soak test is underway. I will try to post the results this weekend.
UPDATE: 03/31/2018 - No noticeable change after the soak test.
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Post by pigbuttons on Mar 30, 2018 18:46:52 GMT -8
Sks, thanks for the updates. Still interesting.
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Post by sksshel on Apr 12, 2018 12:58:31 GMT -8
The first form is poured for the DSR. It's inside the curing box. Temps currently 102 oF on a hazy 80 oF spring day. I've adjusted the water added to the formula downward. You can track progress on the DSR construction here.  |
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Post by sksshel on Apr 30, 2018 14:01:35 GMT -8
6 forms have been poured so far. At this time there haven't been any visible cracks.  This sample is 21.5" x 12.25" x 1.25". This formula for geopolymer has passed all of the tests so far.  |
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Post by smarty on Jul 6, 2018 6:38:46 GMT -8
This is an insulating mix so I guess it’s not very hard? Have you any experience of using it to make a dense concrete type material? Do you think it would work? Say for a weatherproof coating for a pizza oven dome?
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