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Post by permaculturebob on Nov 30, 2019 15:47:38 GMT -8
While I do appreciate, and even have some aptitude for the chemistry of some of these other processes, for the time being I mostly just wanted to get a little success with the easiest most direct process making a geopolymer. Like many new concepts, seeing the process first hand can be a powerful incentive to going deeper into the many variations.
No, I haven't yet taken my zeolite out of the bag (sweet PDZ) but I do anticipate the possible need to grind it to a finer powder. Also, it seems the NaOH needs to be a fine powder also, so maybe part of the dry mixing process can be taking both through a grinder together.
That won't happen for another week or two, but with some luck when I do start playing with the GPs I'll have enough alternatives to get a happy conclusion/
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Post by Deleted on Dec 4, 2019 7:18:58 GMT -8
This is in part why Davidovits' LTGS description called for a 50/50 mix of alkali and alumino silicate to be combined 24 hours before mixing with the rest of the alumino silicate. That is not correct. A semi-plastic 50/50 mixture of alkali and alumino silicate would harden within 24 hours, thus it could not be mixed with the rest ofthe alumino silicate.
The reagent is added as a powder to the dry soil, which then is milled. The sentence "This semi-plastic mixture will mature during atleast 24 hours" refers to the complete hydrated mix of "soil + reagent".
See the PDF "The geopolymer brick LTGS" : 5.3.1 Geopolymeric setting at room temperature: temperature at most equal to65°C.
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Post by permaculturebob on Dec 5, 2019 7:17:43 GMT -8
Thanks for that clarification Karl, I questioned that when I saw it, as the process I remember was relatively quick as far as mixing and applying, with no wait time/ I also remember somewhere that multiple thin layers over a form were better than a single thick one. Is there an optimal time interval between layers? Does the finished piece accept hardware--screws or bolts?
Which would be the better aggregate, clay or sand?
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Post by Deleted on Dec 5, 2019 8:06:40 GMT -8
The general rule for multiple layers for any kind of resins, organic or inorganic, it wet on wet.
Which means that the chemical reactions in a previous layer of resin must never complete before the next layer is added.
It would be better to include hardware during the buildup, than to drill holes later.
The thermal conductivity of quartz sand is much higher than of clay.
Also quartz undergoes several phase transistions during heatup and cooldown.
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Post by smartliketruck on Dec 5, 2019 19:57:43 GMT -8
That is not correct. A semi-plastic 50/50 mixture of alkali and alumino silicate would harden within 24 hours, thus it could not be mixed with the rest ofthe alumino silicate.
The reagent is added as a powder to the dry soil, which then is milled. The sentence "This semi-plastic mixture will mature during atleast 24 hours" refers to the complete hydrated mix of "soil + reagent".
See the PDF "The geopolymer brick LTGS" : 5.3.1 Geopolymeric setting at room temperature: temperature at most equal to65°C.
A 50/50 mix of alumino silicate clay such as kaolin and NaOH at a stiff putty or softer consistency is not going to harden significantly in 24hours at room temperature except by drying. I highly doubt a semi-plastic mixture will be much different but I'd welcome someone to describe a reproducible method to prove that it does harden in such a short time at room temperature. More reactive alumino silicates of course work at a different time scale.
Mixing to the final reagent and moisture concentration, ageing 24 hours and then extruding or ramming to me is counter-intuitive. Re-reading the paper has piqued my interest enough to perhaps try and compare.
My intention was not to suggest that the zeolite binder MUST have 24hours ageing.
If your zeolite is in granular form and about the same solubility as mine you will likely need to add time, intermittent mixing and water additions to get a smooth paste if you don't have the means to grind it.
Last night I played with some of my zeolite that I've milled in my little rock tumbler with large ball bearings My lye is a courser than table salt and I did not grind it any further before mixing. I started with a 50/50 mix and trickling water in as I needed it, the temperature when mixed at 50/50 reached 150ºF. I then slowly mixed in more zeolite and water as needed then finished with a ratio of 4:1 zeolite to NaOH. The majority of the time the mix was glossy olive green except for at one point at around 2:1 zeolite to NaOH I didn't mix it for about 10 or 15 minutes and the mix developed a frosted look that was very thin and mixed back in easily. In the end I cast a tile made with 200g zeolite, 50g NaOH, 100g black "pumice" sand and 7grams chopped roxul fibers. This didn't harden much after 8 hours at room temperature, after about 10 hours at 110ºF I can't push my fingernail into it. Please note that this is in a closed container and the hardening is not due in any large part to drying.
Edited to Add: I don't think using the little rock tumbler is necessarily the best method to make the powder as it takes many hours to produce only a small amount of powder. I'll be looking in thrift stores for a cheap small high speed coffee mill or food processor to try next.
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Post by permaculturebob on Dec 6, 2019 1:08:04 GMT -8
Thanks for the answers to those questions Karl, I'm almost cleaned up from my new DSR install, so the GP experiments will begin soon.
Funny though how sometimes the simple things (like reducing particle size) can take more time than working out the whole rest of the process.
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Post by Deleted on Dec 6, 2019 6:52:17 GMT -8
A 50/50 mix of alumino silicate clay such as kaolin and NaOH at a stiff putty or softer consistency is not going to harden significantly in 24hours at room temperature except by drying. In my tests a 50/50 mixtures with a consistency like toothpaste hardened every time in less than 2 hours. Although I have to admit that 50/50 mixtures with clay remained soluble in hot water, but it was a real pain to do so. I did not wait for 24 hours.
4/1 zeolite mixtures did not remain soluble in hot water.
Maybe you failed to do it properly.
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Post by Deleted on Dec 11, 2019 10:27:22 GMT -8
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