sweet pdz/NaOH experiment about to happen, suggestions?

[permaculturebob]

It would be wonderful if there was a video with off the shelf ingredients, showing step by step with explicit instructions not complicated with theory or other possibilities.

Inevitably looking at the discussions, there are talks of different chemistry possibilities, seemingly trying to bring us up to a level of understanding of how the process works, but mostly just confusing the heck out of me as I impatiently try and get my hands into the geopolymer fun.

But after much reading and many distractions I'm about ready to try my first experiment. I can easily boil water, but long oven curing isn't going to happen, so I think a simple 1 to 4 ratio--NaOH -pdz, mixed dry, then a small amount of boiling water (as small as can completely dissolve the dry ingredients), then wait a short time for the reaction to create the binder, then add more water to get the mix to flow into the aggregate, which in my case is Virginia clay ,unrefined, but a high percentage of clay, sifted through a screen.

Last year when I first read about this, sweet pdz and NaOH seemed the simple way to go, simple, reliable, but the more I read it just seems to open up all sorts of questions,

I'm reading now about this drive to use acid washes and other processes, and wonder why the simple, seemingly easy pdz process isn't used more

does the pdz geopolymer provide refractory quality strength with high insulation- ie: the ceramic fiber board/firebrick hybrid equivalent? or do I need to expect that this polymer will just be an experiment not truly useful in a DSR core, but maybe a nice way to build a wall?

Anyone have any direct suggestions as to what might be a flaw in my plan or a way to make it more fool proof?

[firewatcher]

I think that @coastalroketeer would be your best bet regarding hands-on experience with sweet PDZ. I only tried it a handful of times without success (I never got the sweet PDZ to dissolve fully).

[Berend]

My zeolite is a very fine powder and I got clumps quite often when I tried to add water to the dry mixed zeolite+NaOH.
Instead of dry mixing the zeolite and NaOH, I got more consistent results by wetting the zeolite first and heaping the NaOH into the wet zeolite.

I used the following amounts (spreadsheet):
Mix 80g zeolite + 48g water
Add 20g NaOH and try to keep it concentrated in a single place. This should heat up the mixture quite a bit.
Slowly mix it together.

After about 15-30 minutes I add 102g extra water to the mix.
Finally I add 567g aggregate (0-2mm basalt)

[permaculturebob]

Yes, I've read many of cr's threads and have learned quite a lot reading them.  I didn't want to start asking direct questions until I had some experience and knew more what to actually ask experience. That's why the thread has such a general intro.  The fact that you had problems dissolving the pdz is interesting to me. what did you diagnose as the issue?

My PDZ is in a sealed plastic bag so I haven't even handled the stuff yet.

[firewatcher]

My issue was most likely due to the fact that I had to pulverize my PDZ. The only kind that I could find locally was the type that came as small granules. I used an old blender to get as small particles as possible, but most clay materials that are recommended for mixes are in VERY fine powder (300 mesh or so). The principle (as I understand it) is that the more surface area you have to perform the reaction, the better. This translates into, the smaller particle size you have, the better. Using a blender to create a “powder” out of my granule PDZ, I really don’t know what my particle size was.

The other down side for me was the heating for dissolution of the PDZ. On a small scale (small test pucks - a few cubic inches) it wasn’t that bad to apply the techniques...on a larger scale (think a cubic foot or more at one time), I didn’t think that it would work very well. This is just my opinion though. Others may have come up with an ingenious way to make it work well.

[permaculturebob]

That sounds about right. I figured I might need blenders- or something to reduce particle size, but maybe there is some sort of grinder that might do even better. I'm thinking about an old masticating wheat grass juicer that I never actually used for wheat grass--it had a cheap chrome plating that started coming off right away so I never got to use it with food, but it might be just right for the pdz

[permaculturebob]

Hi Berend, How did your final GP turn out? All the directions I've seen call for the dry mix first

[Berend]

It's about 8 months ago that I did my last experiments.
I did start out with Karl's instructions to create a dry mix first and add water.
But sometimes it resulted in a gritty result instead of a smooth paste.
I guess having NaOH granules did not really help either.

Reading the reasons put forward by Karl I thought it should still be possible to create a local high concentration of dissolved NaOH by heaping dry NaOH into a dimple in wet zeolite. I used just enough water to get the right paste when all NaOH was finally dissolved and mixed.

An added benefit is that I felt it to be much safer to add NaOH to the mixture instead of adding water to the dry NaOH. I had no problems adding all NaOH in one go because there is very limited local water available to get a violent reaction.

Currently I have 3 tiles sized 280x160x12mm and they sound pretty solid when I knock on them and you can barely scratch them.
A (small) torch can heat it up to an orange color and I get the impression it is even harder after cooling off.

[permaculturebob]

Thanks for your comments, I'll likely try it with a dry mix first, then if I have problems I'll try your method. It's good to know there's more than just one procedure that will give results.

[smartliketruck]

In short, mix 50/50 lye & zeolite with the minimal amount of water for a thorough mix and a balance of time and temperature first before mixing with the rest of the zeolite.

It might serve y'all better to think of the lye as a solvent and not an adhesive. (Took me a while to realize this)
If you have two pvc or abs pipe fittings to stick together you can stick them together with only a solvent like xylene or acetone. The joint will not be nearly as strong with just the solvent compared to making a cement by completely dissolving some of the plastic into the solvent first and then using that to join the two fittings. 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. (also to lower the risk in handling the lye uncut) This is why Karl was very adamant about making the concentrated "binder" mix in most if not all threads he started or participated in.
As to water, the idea is to add only enough that the water acts as a bridge between the molecules but if you add too much it will keep the molecules further apart so that it's harder for the molecules to interact with each other. If you have too little water only extreme temperatures or lengths of time will allow the interactions even with finely divided, well mixed materials.

[permaculturebob]

Hi SLT, Your description of the process seems to indicate the "binder mix being created in two steps rather than one, mixing 1-1 first, then adding the rest of the zeolite,creating the correct binder proportions, I assume the aggregate is added next.

Unless I'm reading your description wrong, this is a third way to make the binder.

My original understanding was that the dry mix was done in one step--1-4 and boiling water was added- (just enough to dissolve the mix). The boiling water added some heat and the NAOH dissolving added some more heat to expedite the initial reaction (dissolution) creating the binder. Particle size was important to make the reaction happen at a quicker rate with less need for mixing while the reaction was going on thus preserving the heat needed for a thorough "dissolving" of the zeolite making the binder.

I think your analogy of the acetone and pvc is a very good one for me, it helps with my visualization of the process.

[Deleted]

For the 50/50 mix of lye and clay to make the precursor of LTGS geopolymers Davidovits calcines the clay
and then grinds the calcined clay together with the lye for a prolonged time in a powder mill.
It took me some time to figure out simpler ways for making the precursor.

Adventurous ones however could even add minerals to molten lye.

Very cheap.

www.youtube.com/watch?v=apTqPyTqXF4

Sand:

SiO2 + 2 NaOH = Na2SiO3 + H2O

SiO2 + 4 NaOH = Na4SiO4 + 2 H2O

2 SiO2 + 6 NaOH = Na6Si2O7 + 3 H2O

Kaolin:
Al2Si2O5(OH)4 + 2 NaOH = Na2Al2Si2O8 + 3 H2O

Al2Si2O5(OH)4 + 2 NaOH = 2 NaAlSiO4 + 3 H2O

Sodium clinoptilolite

Na6(Si30Al6)O72*20H2 + 58 NaOH = Na64(Si30Al6)O81 + 49 H2O

Could be broken down further.

[smartliketruck]

Nov 30, 2019 4:25:00 GMT -8 permaculturebob said:

My original understanding was that the dry mix was done in one step--1-4 and boiling water was added- (just enough to dissolve the mix). The boiling water added some heat and the NAOH dissolving added some more heat to expedite the initial reaction (dissolution) creating the binder. Particle size was important to make the reaction happen at a quicker rate with less need for mixing while the reaction was going on thus preserving the heat needed for a thorough "dissolving" of the zeolite making the binder.

I was making the assumption that you'd already tried the 1 to 4 ratio, if your zeolite is a very fine powder it may be possible for you to get a high enough dissolution as zeolite should be easier to attack with lye than say a kaolin clay. I don't have any fine zeolite powder to try, the zeolite I have is granules intended for ice traction, I didn't get satisfactory dissolution when I tried it. If I can find the time and re-locate my zeolite I'll throw some in my rock tumbler and give it a go.

[smartliketruck]

Nov 30, 2019 9:18:17 GMT -8 @karl said:

For the 50/50 mix of lye and clay to make the precursor of LTGS geopolymers Davidovits calcines the clay
and then grinds the calcined clay together with the lye for a prolonged time in a powder mill.
It took me some time to figure out simpler ways for making the precursor.

When Davidovits refers to LTGS he is speaking of his proposal to make bricks of kaolinitic earth with significantly lower temperature firing or much higher strength than simple compressed earth bricks, no mention of calcined clay (metakaolin) that I've seen.

Your more general use of the term LTGS to simply mean what it stands for, Low Temperature Geopolymer Setting, is of course correct but can cause confusion when looking at writings from Davidovits and his followers.

[Deleted]

Davidovits does not write for the general public but for people with an scientific background.
Meta refers to somhething obtained after untergoing a transformation.
Thus there is any kind of metaclay.
Davidovits uses always calcined minerals for making any kind of binder.
Davidovits calcines only the very small part of the kaolinitic earth used to make the geopolymeric precursor AKA binder.