Geopolymers

[Permafacture]

hey there.

This is a great site with lots of practical information.  I'll be digging through here more.

But I wanted to let anyone interested know about a project I am working on.  There is lots of information available about geopolymers, but it seems there is even more confusion.  The information is not so common to have reached that critical mass, where someone can easily get good information or advise based on experience.

So, I am begining a project to make several GP recipes for a number of different applications.  My results, but more importantly, my experiences will be shared on the internet.  What worked but also what dissolved in water, fizzled in vinegar or cracked under heat.

Collaboration is key to this project, to generate as much experience to share as possible, and to make those experiences more valuable by communication during the process.  So, if anyone has been itching to incorporate pozzolanic or geopolymeric components into ferrocement, you should contact me.

Also, after I get some equipment, I'll be able to mail samples or even quantities of prepared ingredients at much less than international producers can offer right now.   

Please follow up with me if you want to be informed of developments in this project, or if you want to participate/contribute. 

www.permafacture.org/geopolymer.html

I am trying to raise money here: http://www.kickstarter.com/projects/410996349/making-geopolymer-technology-accessible

 thanks,
elliot

[Paul Sarnstrom]

Hello Elliot,

I as well as others have read about geoploymers over the years. As you know Davidovits and others have written about them for some time. There are many theories about how they may nave been used in the past, even 1000's of years past and great claims about the potential of geoploymers but so far nothing practical has been demonstrated.

Obviously people who are interested in FC are interested in the possibility of using them in conjunction with FC production.

If you do succeed in discovering materials and procedures to successfully produce them please do contact the FEN as we are interested in doing testing in FC applications.

regards,
Paul Sarnstrom
director, FEN

[wfholch]

Hi Elliot,

yes, there is a lot of information available on GP. some however, is not fully explicit as some researchers have to protect their interest.

i am into this for a number of years (all financed from my own pocket, evenings, after hours).

experimenting wise: i have gathered numerous dust/ash materials here in Namibia and have tried them out, some very promising, are all materials which do not make sense in connection with OPC.
...however, getting hold of the chemicals is a problem here (supplier monopolies and vast transport distances) and makes life difficult at times.
...have seen great regional differences in reactivity of dusts (silt/clay) and have studied a number of different plants for ash production. an excellent material i use for super light GP-foams (0.4g/ccm) is the ash of our Hardap dam reeds. i "fire" the foam and other samples in a solar cooker at under 70 degrees C during the day.

use wise: i like to spray the GPs to coat EPS foam plates or simply use it as a spray-on plaster on FC structures.
...also works well with concrete stainers to get an optically pleasing finish (due to high pH); superb with turmeric/alcohol extract for a fire red colour, you can fix it with a stone sealer afterwards, years later it ends up being a golden colour (used this in my old days as violin maker).
...high fly ash content GPs i use for steel coating or even bearing bushes for simple machinery (together with thread tape)

strength wise: good over night results are 80 MPa, but in general well above 25 MPa depending on the aggregate/clay/ash/hydroxide/silicate mixes. these mixes mostly differ between anthills or samples collected from gravel plains, i.e. a lot of sampling is needed, AND the stuff is not standardized.

market wise: this is the reason why i went for GPs. only 15% of our population can still afford building to standards, the other 85% have no other option than to recycle sheet metal for shacks; luckily there are no standards for corrugated iron shacks, a potential market for GP here in NAM; some of the GPs  can be produced at half price of concrete, outscoring concrete.

equipment wise for experimenting: pretty much what you have in a bush workshop, a high speed mixer (450W drilling machine) for the paste, good mixing is achieved with 8000 hits per minute (watch out for entrapped air) for 45 seconds, a small impeller mixer (goes well up to 1000g at the time), tupperware moulds, a silicon dildo from the next sex shop is a perfect vibrator to get rid of the entrapped air, can support high pH; an old wooden drawer insulated with PET-wool with a 100 W bulb is my over night oven, during day time i use a box type solar cooker ...

best
walter

[Permafacture]

walter:

glad to hear there is some experience here.  As far as standardisation of reactivity goes, have you tried calcining a kaolin rich powder, making resin with that, and then mixing that resin with that less controlled dust?


The property I would like to most develop towards domes and concrete living spaces is the adobe like breath-ability.



paul:
Yes, folks have been writing about geopolymers for some time.  And it is true that the technology has been used since before the term was coined.  Geopolymer is a term created to begin to unify a wide variety of ceramic and cement processes.  For instance, setting sodium silicate with salts or (especially) alumina has been done for atleast 100 years, and I do not think it is disbelieved that eqyptian artisans used acelerated sodium silicate binders to make vessels.

The romans used prozolanic cement, which is known to be chemically related to to the aluminosilicate zeolites that have been produced commerically for 50 years (just guessed at 50).

But I do not understand that nothing practical has been demonstrated. Even just organizing these historical accomplishments is pretty good.  But new advancements have been made also.

http://blog.makezine.com/archive/2009/10/super_cements_aka_geopolymers.html
(check out the linked pdf)

also, an article of military research:
http://www.zinio.com/reader.jsp?issue=416099555
(pg 42)

Lone Star industries in Tx made Pyrament in the 80's. 

I think that the big $$$ that has gone into licensing fee's does not use the word geopolymer so as not to compromise their advantage.  The technology hasn't gotten big because the heads that understand it are under non-disclosure agreements or are financially invested in not sharing the information.

But scientific papers, school projects and tangible products abound.  One can't claim geopolymers are imaginary!  I have sucessfully cured several samples (and made many unsucessful ones) even with the most awkward set up.  My techniques so far have been the equivilant of burning glass and lime with a blow torch to make portland cement. But against these odds, some have still cured. 

[Permafacture]

Walter:

sorry.  suggesting that you build a vertical kiln and calcinate materials that are possibly not available to you was silly.  That is my next step, but I already have an almost suitable kiln available.

Some ideas that are more available to you are (based on reading, not experience):

1. plants that make abundant ash usually have a very high SiO2 : K2O ratio.  Plants that make less ash are probably leaving more alkali concentrated ash (in general).  I think too much SiO2 in relation to alkali to dissolve it would be not as effective.  burned at a low temp prevents the silica/silicate from fusing and being less reactive (I think), unless it is so hot you are vaporizing these things.

2.  Are you using lime to activate the plant ash slurry?  Lime is probably more available to you than lye and it takes part in several useful in situ reactions.  lime + potash = KOH and calcium carbonate.  Also, alkali silicate + Calcium ion = alkali hydroxide + calcium silicate.  I dont know if this calcium silicate is hydraulic (like portland cement), but it is probably geopolymeric and it frees up more alkali to react with things. 

On my list of things to play with is using plant ash as the sole source of alkali, using the two strategies above.

I dont mean to make this a "well i heard that..." geopolymer thread.  I can move it somewhere else if it starts to turn into that.

Thanks!

[upston]

Hi All,

Walter and Elliot, you guys have a lot of great information and I wanted to thank you for opening and contributing to this thread.

Walter how about a field trip through the desert , I would like to hear more details on spraying your GP mix epically on foam or other light weight cores.

I took a look at the bouncing coffee cups on the link , 50 ft onto concrete, not a crack, something big is going on on that one.

Elliot, I would like to get the samples you offered when they are available , please keep us up to date on your progress.

Brad

[Chris Glasspool]

Mud-daubers,

I'm clueless on this subject, and was hoping the thread would continue further. If one wanted to tinker with this: what types of raw materials in what kind of ratios would you be looking for? There is some commercial alternative cements out there now; like Grancrete, these are expensive, but might shed a light on what's possible. Has anyone played with these at all?
Have you heard of Soil-Crete? This was developed by military engineers to make quick air fields. A specific type of soil is found, or amended and then a 10% portland cement is mixed in and compressed. Is this a type of polymer? Or is it still cement particles coating aggregate?
The other question I had is about reinforcement: Since the ph is perhaps different, along with perhaps the ultimate psi, thermal expansion/contraction, and creep; what types of reinforcement are you thinking about: bamboo, carpet fibers, wolastonite, steel, or what?
Sometimes calcined lime is used to stabilize clay soils: Is this a polymer?
Thanks, chris

[Chris Glasspool]

Magnesium - muddies,

I had a interesting talk with the road maintenance crew today. I live at the beginning of a dirt road and it is notoriously known for it's bad dust. The county came in and laid gravel down, with a good grading job, and a roller, and tomorrow they are coming in with a tank of Magnesium Chloride to cement the dust in place. I asked them how this goes, and they said that locally it has surpassed expectation; apparently the local soil, which has a lot of naturally occurring calcium, magnesium, and flyash really sets into a concrete with this treatment. They said that when they grade the roads after this treatment the surface acts just like a type of concrete which throws off sparks as they try and work it.

 I will be doing some trials with this material. Anyone have any ideas on how to mix, apply, and cure for best advantage? Or ideas on mix proportions that would work well? - chris

[Chris Glasspool]

Correction: Our local soil has volcanic ash not flyash. - chris

[Permafacture]

The concept of a geopolymer was sort of gestalt had by a thermoplastics engineer.  One of the practices that fits into the realm of GP before GP was advanced as a concept was the addition of meta-kaolin to portland cement.  kaolin is one of the major types of clay and is a component of many soils, and meta refers to a temperture treatment the clay receives.  Heat treating the kaolin makes it more chemically active.  adding alkali (sodium/potassium hydroxide) to this causes a chemical reaction which has been used to make molecular sieves for over 50 years.

Zeoliths (alumino-silicate molecular sieves are zeoliths) are structurally related to volcanic pozzolan, which are lime activated cements. 

just found this: http://www.bearriverzeolite.com/BRZ%20Pages/pozzolan.html

volcanic ash contains alkali and clays that have been heated and reacted with each other to for the zeoliths and other active alumino-silicates. 

So, the order of reactivity of kaolinitic soil as a cement mixture is: raw, calcinated, calcinated and alkali activated.  Alkali activated will form a hard cement hydraulicly without calcium.  raw clay is really only stabilised with portland cement as an aggregate, and lime/soil bricks must have alot of lime in them because it is only the recarbonation of the lime that is bonding them together.  alkali activated meta-kaolin on the other hand forms a potent pozzolanic precursor.  (that is just book learning, please correct me).

Inorder to be certain that I am witnessing real GP reactions, I have stayed away from any calcium or magnesium.  hows that for "ordinary portland cement"?  So I don't have any experience with using lime in this.

my understanding of bivalent metals (ie, calcium and magnesium) in GP is that through ion exchange the calcium replaces alkali, but because sodium is monvalent and calcium bivalent, two aluminosilicate structures now share a calcium (they each had their own alkali ion before).  alkali activated zeoliths must be present before calcium can have this effect (is my understanding).

there are several good papers in the geopolymer '88 and '99.

in geopolymer '99 (google books) there is information about the project Geocistem and a volcanic ash cement named Carbunculus (what an awesome name!)

in '88 there is atleast one paper on durable ancient concretes which would be of interest to anyone in this forum.  Like, the romans used expanding water-proof hydraulic lime cements to seal the joints in their aqudect plumbing (sometimes holding up to 8 atmospheres of pressure).  (is a free book but i couldn't get it on google books.  check your local library, the '99 book comes with a cd of the pdf's of both confrences).

http://books.google.com/books?id=01_p1yZi-L8C&lpg=PA57&dq=geopolymer%2088&pg=PA44#v=onepage&q&f=false


whew!

-elliot

[Permafacture]

ps:

the volcanic ash deposits are possibly pozzolanic, in which case the addition of bivalent metals ions would cause it to harden.  calcium hydroxide is probably better than magnesium chloride, but I have no experience and very little reading on the subject.  Halides like chlorine are harmful to geopolymers whose structure depends on alkali.  alkali earth cements may not be effected as strongly.

dig it up and try some experiemnts using between 1% and 10% lime by weight.  lime stabalized soil bricks which are not pozzolanic have 7% or more lime.