DIY Geopolymer - code named Kansas City #1

[sksshel]

After further discussion via PM with Karl, I have decided to explore a better geopolymer recipe and procedure. 

My requirements for the Geopolymer are:
(1) well documented
(2) simple
(3) cheap
(4) made from widely available components
(5) consistent components (portland cement is pretty consistent, etc)
(6) Tested - able to withstand the tests of time in an RMH/BBR/DSR/etc

If any changes are suggested and accepted to this recipe, I will update this post with the change and date of the change.

Here's the recipe for Kansas City #1
- 6.1g KOH - I bought mine here (updated 3/1/2018, 3/12/2018)
- 14.5g Monopotassium phosphate - I bought mine here (updated 3/1/2018, 3/12/2018)
- Add enough near boiling water to cause reaction before adding in the remainder of components, add water slowly, the reaction creates further heat.  I added 30ml (1 ounce).  The reaction completed within a minute.  (updated water quantities and timing 3/1/2018)

- add in remaining components
- 100g Kaolin (38% alumina) I bought mine here
- 14.5g Portland Cement - you can buy it here  (updated 3/1/2018, 3/12/2018)
- 10g Rockwool fibers - you can buy it here  Add in the Rockwool and water both a little at a time, stirring it in as you go.  (updated procedure, cut rock wool in half, 3/1/2018)
- add just enough water to make a paste.  I added 4 ounces (118ml).  (added 3/1/2018) (updated 4/12/2018)
- Let the end product cure until hard. 27°C/80°F only slightly above ambient temperatures (20-25°C). (approximately 2 weeks)

Uncured Production Volume from this recipe: (added 3/1/2018, updated 3/4/2018)
- it results in 10.8 cubic inches of product, .18 liters
- it requires 5.6 times the formula to produce a liter of product
- 160 times the formula to make a cubic foot

The product does not pour but does somewhat settle when vibrated.  (added 3/1/2018)

The product shrunk by a little under 10% after 10 days in the curing box.  (added 3/11/2018)

Once the initial curing is complete, the final product should be water stable
.  It should keep its shape and sharp edges after being soaked in water for 24 hours.  Ceramic-like properties including full water resistance are obtained after firing at elevated temperatures.  This should be done gradually at first.  (added 3/4/2018)

- 1 cu ft of the product costs around $40.  (added 3/1/2018, updated 3/4/2018)
- 2.5 cu ft of the product is needed to make the batch box portion.   The components cost a little under $100.   (added 3/1/2018, updated 3/4/2018, updated 4/4/2018)
- 1 cu ft is needed to make the shoe box portion at a cost of about $40.  (added 4/4/2018)

[sksshel]

Here's some information about the thermal conductivity and density of these components as they apply to a rocket heater: (updated 3/5/2018)

At high temperatures kaolinite is converted into mullite and quartz.

Melting points:
Quartz ~ 1670 °C - 1713 °C / 3038 °F - 3115 °F
Mullite ~ 1840°C / 3344 °F
Alumina ~ 2.072 °C / 3761 °F

Therefore white clays with at least 30% alumina can be considered as heat-resistant up to about 1700 °C / 3092 °F
Thermal resistance depends on the alumina content
and that a higher alumina content is also linked to a lower thermal conductivity.
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.
A mixture of Monopotassium phosphate will give a higher heat resistance than a mixture of sodium water glass.

This formula yields about: (added 3/13/2018)
23.6 % KAlSiO4 Kalsilite - melting point~ 1750 °C / 3182 °F
11.8 % Ca3(PO4)2 Tricalcium phosphate - melting point ~ 1670°C / 3038°F
The kalsilite will be created once the geopolymer starts to crystallize above 500°C / 932°F
Note: even the 23.6% require elevated temperatures of at least 85°C/ 185°F or many weeks of ambient curing.

Alkaline aluminosilicates have typically a density around 2.5-2.7 g/cm3
  (added 3/5/2018)
with a hardness around 6-7.
A Knife Blade has about 5.5.

Those are not my words.  I am parroting many comments from others here on these forums.  

[firewatcher]

Feb 28, 2018 11:59:03 GMT -8 sksshel said:

After further discussion via PM with Karl, I have decided to explore a better geopolymer recipe and procedure. 

My requirements for the Geopolymer are:

(1) well documented

(2) simple

(3) cheap

(4) made from widely available components

(5) consistent components (portland cement is pretty consistent, etc)

(6) Tested - able to withstand the tests of time in an RMH/BBR/DSR/etc

If any changes are suggested and accepted to this recipe, I will update this post with the change and date of the change.

Here's the recipe for Kansas City #1
- 4.2g KOH - I bought mine here
- 10g Monopotassium phosphate - I bought mine here
- Add enough near boiling water to cause reaction before adding in remainder of components, add water slowly, the reaction creates further heat

- add in remaining components
- 100g Kaolin (38% alumina) I bought mine here
- 6.5g Portland Cement - you can buy it here
- 20g Rockwool fibers - you can buy it here
- Let the end product cure until hard. 27°C/80°F only slightly above ambient temperatures (20-25°C). (approximately 2 weeks)


Once I have the cured production volume from this recipe, I will update this post here.

Once I have the costs for a batch box core, I will update this post here. 

Unless I missed it (this is a key component as far as I’ve been told) can you include the amount of near boiling water that you used. If I missed this information, I apologize.

[sksshel]

Yes I will add that once I've determined the water amounts.

[sksshel]

My first test batch has been made. 

Updates to original post were made.  I made several changes to the recipe due to mathematical errors.  Other changes are noted as well. 

[pigbuttons]

One question???

You don't mention water resistance/water proofing as one of your criteria. Have you done any water saturation testing of your earlier experiments?

[coastalrocketeer]

Mar 2, 2018 20:31:03 GMT -8 pigbuttons said:

One question😧

You don't mention water resistance/water proofing as one of your criteria. Have you done any water saturation testing of your earlier experiments?

Good question...

Karl has suggested a 24 hour soak test as a method of determining true and successful geopolymerization in the past.

With the requirement that thin parts or corners, of a fully cured test piece, should keep their shape and strength after 24 hours submerged.

I think i remember sshkel listed that "waterproof" requirement in his other thread about the prior version of this mix, before he created this project to produce a well documented, repeatable, optimized
mix and procedure, and either intentionally or unintentionally did not include it here.

[sksshel]

I will add that requirement and subsequent test. I need it to be water proof.

[pigbuttons]

Feb 28, 2018 12:10:31 GMT -8 sksshel said:

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.

When I started experimenting Karl had his own web site, at that time I recall something about the alumina in clays being difficult to react if the concentration was too high. But I can't remember all of the details. Sorry.


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. I'm hoping to get something less susceptible to abrasion.

By the way, has anyone heard from karl lately??

[Deleted]

To pass the test if it is a geopolymer it needs only to keep the shape and sharp edges,
even if thin, keeping much strength while soaked with water is not a requirement.
Davidovits calls this water stable.
The next level are ceramic like properties,
which includes full water resistance.
Ceramic like properties may require elevated temperatures.

[briank]

Awesome documentation, thank you!!

I’m really looking forward to following developments in this thread.

Just out of curiosity, can this be painted or pasted on any other material? For instance, applying it to stainless steel or a kiln shelf might help strengthen a firebox roof or primary bell cap. (Suggestion - Engineer for the least competent, most error prone do-it-yourselfers to provide a very wide margin of error - and for protecting the less well educated diy folks from themselves. There’s a definite utility in over engineering.)

[pigbuttons]

Hey Brian,

Check out this thread to answer your question:Karl's tiny stove

[pigbuttons]

Mar 3, 2018 14:46:02 GMT -8 @karl said:

To pass the test if it is a geopolymer it needs only to keep the shape and sharp edges,
even if thin, keeping much strength while soaked with water is not a requirement.
Davidovits calls this water stable.
The next level are ceramic like properties,
which includes full water resistance.
Ceramic like properties may require elevated temperatures.

Great to hear from you again karl. It was quiet around here for the two weeks you were gone. I hope you are doing well.

[briank]

Mar 3, 2018 19:54:40 GMT -8 pigbuttons said:

Hey Brian,

Check out this thread to answer your question:Karl's tiny stove

Yes, I’ve seen that, thanks. I was just wondering if this particular recipe in this thread was amenable to similar techniques. (Maybe they all are? I don’t know yet.)

[sksshel]

I've adjusted the volume numbers a bit and included the information on water resistance.