Karls LTGS Brick, Ram Mass: Dirt Cheap Geopolymer Refractory

[Jura]

I need to get deeper into  chem logic of what you have done, but for now IMHO my conclusion is that as Davidovits says  you are obtaining some alkali activated material not a geopolymeric structure.

The logic drives us to ask why the oligomers crosslinking process does not occur. if it did you would have obtained a material with a high Young module value. 

I'm wondering whether this step  is   the  mistake or not.

" to the "binder" mix of 20g kaolin 6-tile + 20g of vinegar I added 20g of NaOH"

How did you come up with the step of  applying NaOH?

base + acid -> salts 

in this case sodium acetate CH3COONa +H2O (highly soluble salt)

What is the origin the slag you used ?? 

[firewatcher]

I believe that this is just part of the definition of creating an LTGS mixture as i understood it (from the paper that Karl shared at the beginning of this thread...as well as "recipes" that he shared):

You choose what % of binder you would like the mix to be (in my case for this trial it was 20%), so my understanding was that this means (very basically) that the "binder" is made up of 10% acid activated clay + 10% lye (making the 20% binder total)...and then another 80% clay (acid activated or not acid activated). Then to that you add some aggregate.

Am I misunderstanding? I would have to look a little bit, but i'm sure that i could find my posts with Karl which i used to make certain that this was correct.

As far as the slag, it is a sandblasting slag:
www.menards.com/main/building-materials/concrete-cement-masonry/bagged-concrete-cement-mortar/black-blast-blasting-sand/p-1444445322601.htm

[Jura]

Sept 21, 2017 7:02:23 GMT -8 firewatcher said:

I believe that this is just part of the definition of creating an LTGS mixture as i understood it (from the paper that Karl shared at the beginning of this thread...as well as "recipes" that he shared):

Am I misunderstanding? I would have to look a little bit, but i'm sure that i could find my posts with Karl which i used to make certain that this was correct.

Or maybe my knowledge of contemporary state of art in the field is not full..anyway

It seems I need to peruse over the topic for longer.
(but whole next week I'm busy from dusk till down. So it is going to take some time.. )
It's been 15 years since I graduated and the inorganic chemistry was not my strong point.
The chemist part of mine dislikes the word "activation".
All the substances of minerals we deal with are chemically active.
The polymerization reaction just needs proper substrate (oligomer)and conditions and environment (I got used thought it was the alkaline one)

Have you seen this part of the video where Davidovits shows how the polymerized silica materials looks like?
Hard and unbreakable. There he also explained why.
Polymers are long inter -crosslinked chains thus strong.
if a material breaks in hand it is definitely not a polymer.
Take aerogel as an extreme example of a geopolymer.

[Deleted]

firewatcher I don't intend to be active again, but this is just unbearable.
I have told you that with your rather coarse slag you can use only about half the amount
of the very fine slag I have used in my experiments.
For a castable LTGS mixture the upper limit of your coarse slag is about 50% of the clay content or about 1/3 total.

Based on price and Alumina content I have once recomented kaolin 6-tile.
Later I stumbled over the information at digitalfire.com, that kaolin 6-tile
is not a natural kaolin, but a designer kaolin with lots of bentonite.
I have told you that the bentonite increases the water demand far to much
to be useable for a castable LTGS mixture.

Very likely you got other things wrong too.

Although castable mixtures are possible, the LTGS technique is most suitable for non castable
low water mixtures like kneading or ramming mixes for slabs or bricks,
but can be used for any traditional earth building technique like adobe as well.

Interested people may send me private messages, which may be answered or not.

[firewatcher]

Sept 22, 2017 6:27:25 GMT -8 @karl said:

firewatcher I don't intend to be active again, but this is just unbearable.
I have told you that with your rather coarse slag you can use only about half the amount
of the very fine slag I have used in my experiments.
For a castable LTGS mixture the upper limit of your coarse slag is 50%.

Based on price and Alumina content I have once recomented kaolin 6-tile.
Later I stumbled over the information at digitalfire.com, that kaolin 6-tile
is not a natural kaolin, but a designer kaolin with lots of bentonite.
I have told you that the bentonite increases the water demand far to much
to be useable for a castable LTGS mixture.

Very likely you got other things wrong too.

Although castable mixtures are possible, the LTGS technique is most suitable for non castable
low water mixtures like kneading or ramming mixes for slabs or bricks,
but can be used for any traditional earth building technique like adobe as well.

Interested people may send me private messages, which may be answered or not.

Sorry about that Karl, I guess that I missed the information on not being able to use the 6-tile for LTGS mixes.
I'm not trying to anger you...just trying to get to the point where I have a mix that works likes lot of the other people here on the boards.
There are so many different mixes here and maybe I just need to ask a lot of very specific questions as to what materials are used in a given mix before trying anything out for myself.
Many people say that they used "kaolin" (I am guilty of this as well) obviously there are many different kinds of kaolin so that statement doesn't really help anyone who may be trying to mix up a batch of a shared recipe.

[Deleted]

firewatcher kaolin refers always to natural kaolin.
Natural kaolin clay is not very plastic,
thus if a kaolin is termed as plastic it is very likely a designer kaolin.

The problem for people located in the US are the insane prices.
Looks like capitalism does not work well in the US.
In Germany I can usualy get clays, grog or stone flour
for roughly half the price requested in the US,
even if it has been shipped over an ocean.

Grog mixtures are the simplest and although grog is relatively expensive
still cheaper than commercial refractory mixtures.
Quick lime works best as an accelerator.
Hydrated lime works best if slacked for at least five years.

A mixture of 1/3 nepheline syenite and 2/3 clay can be hardened with about 4% citric acid.
A one by one mixture will be significantly stronger.
The result will not decay in water but becomes rather weak it saturated with water.
Not a real problem, as in a stove this should never happen.

With additional phosphoric acid the result will become much more water resistant
and also significantly stronger.
Geopolymers with phosphoric acid adhere much stronger to surfaces,
thus surfaces should be very smooth and the use of a release agent is recommented

Nepheline syenite is not expensive and due to the very much lower water demand
in an acidic environment even cheap ball clays may become useable.

[Deleted]

Jura the result of the LTGS technique is a highly filled geopolymer,
as most of the clay does not react and thus merely serves as an aggregate.

There are more similarities to sintering techniques than to other geopolymers.
The LTGS binder has similarities to fritts used in pottery to lower the sintering temperature.
It was developped for lateric clays because sodium and potassium ferrates/ferrites
have low melting points respectively decompose at relatively low temperatures,
which supports sintering at unusualy low temperatures.

[firewatcher]

@karl,

Would you say, then, that the remainder of my Kaolin 6-tile is not useable for ANY sort of refractory? Or is it just not usable for LTGS mixes?
I would hate to waste it, but I also don't want to waste anyone's time including my own trying to use it and getting failed mix after failed mix.

[Deleted]

firewatcher you have told me that you had made a mixture with low slag content, which you could not break.

[firewatcher]

Sept 23, 2017 6:20:44 GMT -8 @karl said:

firewatcher you have told me that you had made a mixture with low slag content, which you could not break.

@ Karl,

Unfortunately this is the same mix that had a large amount of shrinkage, probably due to the large amount of waterglass liquid used?

The mix was tried just to see what would happen...since I wasn't having any success with other mixes.

200g kaolin 6-tile (non acid activated)
275g waterglass liquid (330g TSP90 per 1L of water)
20g hydrated lime
20g lye
60g of my too large slag sand

At the time that i had tried this mix, i did not record how long I let it ambient temperature cure for (most likely 2-3 months as i figured that it probably wouldn't work well anyway and was trying other mixes at the time).
I have also never "camp fire cured" this sample.

[Deleted]

firewatcher I have never experienced such a large shrinkage, not even with a bentonite geopolymer.
Sealed curing is recommended.
Superplasticizer can be used to reduce water.

Natural clays without acid treatment have a very low reactivity
and thus require curing temperatures around 90°C.