Geopolymers

So I have been using geopolymers for a few years and have done some experimenting, but I have so much more to learn. First off the definition.

A geopolymer is a polymer that uses repeating mineral chains instead of repeating carbon chains. Most often found with a silica alumina bridge to link them. So Silicon and Aluminum have replaced the carbon, however, there are geopolymers that use phosphate and aluminum as well as others some found in nature. Caliche clay being one.

What is it good for? It can be used as a cement and thus blended with aggregates to make concrete. It is usually stronger than portland based concretes and unlike portland, the lifespan of a geopolymer concrete is measured in thousands of years. The great pyramid was made of geopolymer concrete or re-agglomerated stone as some would put it.

So if you feel like experimenting. Most of the tests I have seen, the greatest strength of a geopolymer concrete in freezing climates would contain 22% cement and 78% fill. You must mix the reactive materials together first and then add the aggregates. This helps the chemical reaction to start. It is also a good idea to keep the mixture covered until it sets.

If you have blast furnace slag available and it was quickly quenched. then:

a reactive clay that has been calcined. many use metakaolin calcined at 1382˚F or 750˚C called MK750 20-30 parts

Potassium silicate a water glass K2O: 26%, SiO2: 21%, H2O: 53% 25 parts
Not all water glass is equal, it must contain the smaller SiO2 molecules to be reactive
so you will have to test what you get or get it from someone that works with geopolymers

blast furnace slag with average grain size of 8 micrometers 27 parts
if it was poured into pits and allowed to cool slowly it will not work
anything from quick quenching to slabs poured one inch thick should work

water (be careful here the more water in the overall mix the weaker the concrete will be) 20 parts

This is taken from Geopolymer Chemistry & Application by Joseph Davidovits
I highly recommend his book if you would like to learn more but he has many free papers you can download
and learn what many scientists are doing around the world.

Many of these can be made using plant ashes. So you could say use rice husks to heat up your Rocket mass heater and then use the ash to make your own water glass.

And for fun here is his recipe for a pyramid stone:

528 gallons of water
353# kaolinitic clay
132# sodium carbonate
176# slaked lime
mixed and let to set for 24 hours then add
9,921# of crushed limestone

Pise the mix into molds and when dry you have a pyramid stone.

I mixed 10M lye with the red dirt of Thailand and made red stone-like bricks that set at the ambient air temperature. But that is Thailand hot.

I think Geopolymers are a great way to build things that will last and you can use waste products to make them. And calcining uses a lot less energy than making portland cement.
Oh and one more thing. Geopolymers will not explode when they get too hot like portland cement will.

Jason Learned : You are off to a great start, a respectable number of visits for a new subject and much better response than average. Thank you for posting !

Cold Climate Housing Research Center a Branch of the University of Alaska, Fairbanks, is also doing quite a bit of research of Geopolymer cements/concrete on
cold weather usage and general usage as portland cement primarily comes to Alaska from Korea ! Big Al !

I should clarify that most geopolymers can be caustic. However with the potassium based ones you can use a lower PH and still get the same ore stronger finished product that would require a higher PH with sodium. The reaction up above in the pyramid stones creates caustic soda but with so much stone I think the PH should be fine, however, some of the blocks in Egypt had magnesium chloride added which would have brought the PH down and helped form hydrated magnesite in the re-agglomerated stones.

So if you want a non-caustic but still an irritant mix you will have to watch your molar ratios. To be an irritant instead of corrosive you need a molar ratio that is SiO2:M2O > 1.45 (M is the alkali mineral, Li,Na,K etc). But if you have gloves and goggles and are careful and know which end of a shovel to use it should be no problem. The recipes up above even the pyramid one are irritants once completely mixed. Notice the slag based one is only an irritant as a cement, it still has to have the sand etc mixed in with it to make a concrete.

Hello Jason,

Thank you so much for starting this post thread on Geopolymers!

I would be great, if during the course of your research, and discovery, you share your findings here. I know many of us would find it of great use. I have been following Geopolymer research for about a decade, but have never found the time or material availability to facilitate a full scale project, particularly a foundation, as well as, other architectural applications.

Have you built anything full scale as of yet?

Can you post photos?

How hard is it for you to gather materials for making Geopolymers?

Thanks again for starting this post.

Regards,

jay

Hello Jay C. White Cloud,

The biggest thing I have built so far with geopolymers is the foundation for my pizza oven barbeque. It is very strong, but my time for working on it is sparse. The guy I worked with in Thailand has built many larger things. He was negotiating to build the roads on an island near Papua New Guinea, but graft did that deal in. I think that would have been the largest thing ever built. They just finished a building in Australia where the floors were all precast geopolymer sections. When I finish and test my pizza oven I will post some pictures. We started experimenting to make some of our panels out of geopolymers for our geodesic domes but put that on the back burner because we left Thailand. As for getting the supplies. It has been rather easy for me to get things in Europe. And there are even water glass suppliers that know how to make the correct types of water glass for these applications. I know there are many geopolymer researches in the US now. They hold a conference once a year over there. So there must be some suppliers over there as well. If I come up with a good recipe I will share it for sure. I had a nice one made with barley straw ash, but I did something wrong and it crumbled with time, back to the drawing board.

One of the main things you need is reactive clay. Bricks that are misfired and are not strong enough are usually good candidates. That was the secret ingredient in Opus Signinium that the Romans used to line their aqueducts and cisterns. For you to make the same; your clay has to have analcime or phillipsite in the mix, this will react with lime to end up making hydrated gehlenite and feldspar like minerals which will be strong and waterproof.

Jason :
Jay C. : Rushes are famous for their ability to take up silica and make it part of their wall structure, with miles of rushes growing on acre feet of Zinc mine tailings,
around here, mostly horse hair rushes slow grow ing on damn poor soil, the use of rushes for structural Cob or with larger specimens as a potential silica rich ash
seems like an area worth researching ? Any Ideas ! Big AL !

Hi Allen,

The idea of processing silica from horsetail rush sounds very promising. Where I question validity in many of these concepts is the practical application, logistical achievability, and viability for the scope and volume needed to even do a small project. So many of these concepts can only be achieved if executed on an industrial level of processing. That is why I have been trying, over time, to teach myself how I can take local resources already in the manufacturing "product stream," and repurpose them into components for geopolymers. Doing this, and having it be cost effective and logistically viable is the challenge. This is still why, "icky" old portland still "rules the roost," for cultured masonry and concretes. I am still looking and leaning about this medium, but it still seems a ways off?

Regards,

jay

One of the reasons why my barley ash failed was I did not remove the carbon. It should be taken out.

Here is a table of ashes percentage by weight taken from Davidovits' book

----------------------SiO2-------CaO-------MgO-------NaO-------K2O-------P2O5-------SO3

Beech; trunk--------5.4--------56.4-------10.9-------3.6--------16.4-------5.4---------1.8

Beech; branches----9.8--------48.6-------10.6-------2.4--------13.8-------12.2--------0.8

Beech; leaves-------33.8-------44.9-------5.9--------0.7---------5.2--------4.7---------3.6

oak------------------2.0---------72.5-------3.9--------3.9---------9.5--------5.8---------2.0

apple tree-----------2.7---------70.9-------5.5--------1.9---------11.8-------4.5--------2.7

hazelnut tree--------1.07-------81.5-------5.2--------0.4---------2.8---------0----------0

acacia---------------5.5---------74.2-------2.1--------0.3---------9.6---------3.7--------2.7

fern-----------------6.1----------14.1------7.6---------4.6--------42.8------- 9.7--------5.1

bulrush--------------11.0--------9.4-------6.3---------6.6--------36.6--------6.3--------8.8

reed-----------------71.4--------6.0-------1.3---------0.26-------8.6---------2.1--------2.8

heather-------------53.2--------18.8------8.3---------5.3--------13.3--------5.0--------4.4

barley straw--------53.8--------7.5--------2.5---------4.6--------21.2-------4.3---------3.6

wheat husk---------68.53-------7.23------1.88--------0---------8.03--------2.23--------0

rice husk------------92.83------0.46------0.49---------0---------1.94--------0-----------0


I am sure your horsetail would have more silica as would seagrass. And there are very few out there working with ashes so much of the knowledge has been lost. I remember hearing an old tail that to make soap you had to put enough ashes into a barrel until a potato would float enough that a sixpence size piece of it would be exposed. That would give you a strong enough concentration to add the grease to make the soap. Maybe there are some old sayings about making concretes like this. Supposedly some of the ingredients used by the Egyptians to make their statues came from palm ashes.

Any insights are welcome. The theory for the Venus found in Czech from 25,000 years ago was the clay was mixed with fern ashes and oak ashes to create a geopolymeric reaction at campfire temperatures making a ceramic without having a kiln.

If you have volcanic ashes near you then you can just use lime and you are golden!

Jason

So this is my geopolymer pizza oven and fireplace/grill. I've run out of time for the moment, so next year I will have to construct the burn tunnel and riser in the back and under the oven. The burn tunnel will be made out of the same material the whole concrete looking parts are made of and the riser I will experiment with DE.

The concrete is three parts high silica sand (half fine and half coarse) mixed with one part BAUCIS L 160 which is a geopolymer cement made by a local mine that produces fire bricks. This product is calcined grey shale with sulfate added to stabilize it and the liquid used is potassium water glass and potassium hydroxide at a concentration that makes it an irritant instead of caustic. For the burn tunnel I will do a tenth cement and 9 parts silica sand with the thought that if the cement does burn out the silica will sinter and leave a strong block in its wake. The melting point of this cement is 2192˚F so it should hold long enough for a sintering to take place. With the riser I am going to try some different things. The plan is to build three RMH/ cooking type things on the property so I have room to play with recipes. The DE I will use is the kilned stuff so the melting point is the same as silica meaning I can melt iron in it. Now it is just playing until I find the right binder that will hold it long enough for it too to sinter and be cheap!

So far the material has held out really well in the tests. It is much stronger than Portland cement and has an expected lifespan of thousands of years and cost only a little more than Portland.

The insulation is a combination of rock wool and perlite. And the floor and ceiling are firebrick so I can replace them as they burn out. If I build another I will only use firebrick on the floor of the oven. In the area of the ceiling where the riser will blast I will create a thick removable section that I can replace if it does burn out with the rocket blasting in the same spot.

Will update next year as I progress.

Jason

Jason, are you still viewing this thread? Do you mind if I ask some questions?

Yes. I view it and will continue to post as I make breakthroughs. Albeit the breakthroughs have been slow in coming lately.

Jason, I gather you are a chemist? I had a hard time following the dialog, do you mind if we start with the basics and some practical examples of materials?

"A geopolymer is a polymer that uses repeating mineral chains instead of repeating carbon chains. Most often found with a silica alumina bridge to link them. So Silicon and Aluminum have replaced the carbon, however, there are geopolymers that use phosphate and aluminum as well as others some found in nature. Caliche clay being one. "

So would hempcrete or strawcrete be a "geopolymer" ? From what I understand, the hemp plant has high silica content(80-90%) like no other plant that binds to the silica in lime to make hempcrete? Is that true, or is there another chemical bond like with MGO? I found on the internet that wheat straw also has a high silica content of around 60%, others straws and grasses with silica. Straw is more readily available than hemp in the US but, farmers are now growing it, and seems to work but, I'm not sure about this theory of it recurring absorbing CO2 to revert back to rock when it gets wet and the bond getting stronger indefinitely? I wonder if that has every been quantified and proven.

Or am I way off track and these cretes are not in the family of " geopolymers"? If you don't mind, please simplify your answer for the non-chemist

Thank you.

Hi Jane,

I tried to reply earlier but through my phone and after writing three paragraphs and pressing enter it said for me to log in and it was lost so here we go again.

Okay, I did some limited research ie wiki on hempcrete so take this with a grain of salt. It looks like most hempcretes do not use geopolymer cements or create them from what I could see. One thing is a well prepared geopolymer concrete should have a compressive strength of anywhere from 7,000-15,000 psi a really poor one would be in a portland cement range of 3,000 psi, but it looks like most hempcretes are 145 psi. That is really low. Now I saw that some people use pozzolans (volcanic ashes) in their mixes and the right kind of pozzolan will help create the cross bonding you need to create those geopolymeric chains that make this type of concrete different from Portland.

Okay so I would not consider myself a chemist. I did well in my chemistry classes in university, but chem was not my major. I have had to use chemistry in some of my jobs but I do not receive my income from being a chemist so I think I am more of an enthusiast. I also think that this chemistry is not too complicated and I am sure that you could learn it really quickly, so don't get turned off by a few weird terminology words please.

Next thing, if a concrete uses lime carbonizing meaning going from calcium oxide to calcium carbonate to gain its strength it is not a geopolymer. Calcium carbonate is not that strong, it makes a great plaster, the sistine chapel is done with this chemical reaction, but it does not have the strength to hold up a large heavy structure for a very long time. It can be used as a mortar for bricks and be repointed every 100 years but it is not a geopolymer. The geopolymer makes those long chains that will cross link in a similar way to plastics but uses other chemicals than carbon so they don't burn. Some geopolymer cements use lime, but with other chemicals like sodium carbonate to create free sodium hydroxide which is strong enough to break the silica alumina bonds and allow them to reform in a new configuration. This is where the pozzolans could also create a similar reaction too.

Now is it possible to make a geopolymer hempcrete or other type fiber crete geopolymer, I am sure it is. BASF may have done so already but they probably have just patented it and then will sit on it for years. And people are experimenting all over the planet with this stuff. There was one paper that argued that cob gets some of its strength from geopolymers in it. The theory was the clay is allowing slight decomposition of the fibers with biological interaction and then in that humic acid environment silica alumina bonds are forming giving the cob greater structure and strength. Who knows, it could be true. That could be one method of making a hempcrete that would be stronger. I think with the current mix it creates a too sterile environment where bacteria cannot grow preventing this from happening, but that is just my theory on it. If you were to burn the hemp to extract the silica you could use that to form a geopolymer cement without trying to rely on bacteria.

So I guess what I am saying is that it should be possible, but if you don't get a product that is at least 3,000psi in compressive strength (tough enough to use as a hard brick) then you are not getting enough chemical reactions and cross linking to call it a geopolymer concrete. That does not mean you could not use hemp or others and a reinforcing material in a geopolymer cement to make a stronger concrete. That may be a good experiment to try. I know some people use poly vinyl alcohol fibers for reinforcement because they will react but not get brittle like fiberglass will.

I hope this helps and I was clear enough for you.

Jason,

That was a great post above...thanks again for all your work on this thread. I really look forward to every entry, as I really see this "ancient" method being rediscovered with new enthusiasm and creativity. We need a more environmentally sustainable product that OPC based cements. Leave it to the ancient Romans and Egyptians to lead us on a path we had forgotten.

Regards,

j

Jason, thanks for taking the time to re-answer my questions. See attached, I ran across this article and magnesium cement. Excellent properties that bind well with cellulose. The properties seem hard to beat (see quote below). How would geopolymer cements compare?

"Magnesium-based cements commonly achieve compressive strengths of 9,000 to 45,000 psi and tension strength of over 800 psi, many times stronger than that of conventional concrete. Magnesium oxide combined with clays and cellulose form cements that breathe water vapors electro-magnetically, a significant plus. The clay in magnesium oxide balances and enhances the movement of moisture. It never rots because it always expels moisture. Also, unlike Portland cement, MgO cements will not drain the charge out of a car battery left overnight on a floor made with as little as 20% MgO content. MgO cements are completely non-conductive of electricity, as well as heat & cold, and have been used for flooring for radar stations and hospital operating rooms throughout the 20th century."

Thanks for sharing the article Jane, that is a geopolymer they are describing in the article.

Hi Jane,

I worked work mgo a great deal when I was in Thailand. It is a great material and mag oxide is a great additive to most cements to improve properties. We added 3-5% magnesium sulfate and 7-9% magnesium silicate to give it acid resistance and improve its water resistance. Magnesium oxychloride can be soluble in water until it absorbs enough CO2 to create magnesite which is insoluble. They told us it would dissolve and could not be done, but with the talc added we tested fish tanks made out of it and they held up.

Jason.

[\quote]slight decomposition of the fibers with biological interaction and then in that humic acid environment silica alumina bonds are forming

This is how Sepp Holzer creates ponds, lakes and earthen dams. He's smears a fermented pig poopy all over what is to be water proofed and then fills with water. ----------------------SiO2-------CaO-------MgO----

[\quote]---NaO-------K2O-------P2O5-------SO3

Beech; trunk--------5.4--------56.4-------10.9-------3.6--------16.4-------5.4---------1.8

Beech; branches----9.8--------48.6-------10.6-------2.4--------13.8-------12.2--------0.8

Beech; leaves-------33.8-------44.9-------5.9--------0.7---------5.2--------4.7---------3.6

oak------------------2.0---------72.5-------3.9--------3.9---------9.5--------5.8---------2.0

apple tree-----------2.7---------70.9-------5.5--------1.9---------11.8-------4.5--------2.7

hazelnut tree--------1.07-------81.5-------5.2--------0.4---------2.8---------0----------0

acacia---------------5.5---------74.2-------2.1--------0.3---------9.6---------3.7--------2.7

fern-----------------6.1----------14.1------7.6---------4.6--------42.8------- 9.7--------5.1

bulrush--------------11.0--------9.4-------6.3---------6.6--------36.6--------6.3--------8.8

reed-----------------71.4--------6.0-------1.3---------0.26-------8.6---------2.1--------2.8

heather-------------53.2--------18.8------8.3---------5.3--------13.3--------5.0--------4.4

barley straw--------53.8--------7.5--------2.5---------4.6--------21.2-------4.3---------3.6

wheat husk---------68.53-------7.23------1.88--------0---------8.03--------2.23--------0

rice husk------------92.83------0.46------0.49---------0---------1.94--------0-----------0

Is it be possible to mix and match different ingredients to come up with a cement with specific properties?

Kris Johnson : Fast answer- It depends ! There are a tremendous number of reasons to transition away from Portland Cement based Concrete !

Every step of the process of its manufacture requires large inputs of energy, And its a crappy product with many better analogs !

Here is a link to work being done by the Cold climate housing research center an arm of the University of Alaska (Fairbanks),*

This should help get you up to speed ! Link below !

http://www.cchrc.org/geopolymers-what-are-geopolymers-made

Good luck and good hunting ! For the Crafts ! Big AL

* In Alaska all Cement is imported- mostly from Korea/ the pacific rim A.L.

Thanks for posting that video Big Al!

It amazes me that there are so many superior (compared to PC) cements ( good article on magnesium cement and a builders applications http://greenhomebuilding.com/articles/ceramicrete.htm) out there but they haven't really caught on in mainstream use. I suppose it is probably due to price and availability. The geopolymers seem like for the most part they are only available to someone that has the time to collect the raw materials and figure out good recipes. There are companies that produce magnesium based cements, but there are limits to getting their product ie they only ship to certain places, have large min orders, and are somewhat cost prohibitive (depending on budget).

Arogonne labs did some great work and licensed some in the US and are not active anymore as far as I can tell.....Grancrete whom I called a while ago and got no answer. I did talk to a builder that tried their MGO for shotcrete that said it dried fast and clogged the gunite. Premier below has got into the US MGO market making raw materials. China is the biggest raw material supplier to most mag boards and products. Premier offers a MOC (see below) they claim China does not...but they seem to be marketing to manufacturing and offer no applications like boards, SIPS, cements, etc...they make a cement additive that is hard to get my ready mix company to change to I told them. I also wrote them to try to develop some applications, design procedures, like Grancrete had. No answer, nor when I questioned what gun they proved their shotcrete mix in? They are the only raw US raw material supplier I know of? and are fairly new at it.

They'll send you small samples 5 mg and you need to locate a chloride or phosphate additive. I'm no chemist with a lab to develop applications I told them, they have stater mixes on their site. I suggested they make it easy for builders, and there is a big home building market out there if they can. They claim to be competitive in price to portland cement and China....I have some fly ash, can get some MGO, I just got no idea what to do with it lol! Yet anyway. I'm reading a book called "breathable walls" by George Swanson....He got one of the Argonne licenses....After I read the book I'm planning on heading down to TX to pay him a visit. I'd settle for mag board to start if it is cost competitive. Word on the street is be careful with import quality. MGO corp is another I just found out about, they boast about there certifications in several countries and US=ICC code compliance, Magnum another, both located in Florida next to shipping docks..I heard through Magnum supplier they are shipping in from China probably the same as MGO corp.

http://www.premiercpg.com/PREMag_MPC.html

Here is some of my research notes...

Dead burned magnesium oxide (MPC) : Temperatures used when calcining to produce refractory grade magnesia will range between 1500ºC - 2000ºC and the magnesium oxide is referred to as "dead-burned" since most, if not all, of the reactivity has been eliminated. Refractory grade MgO is used extensively in steel production to serve as both protective and replaceable linings for equipment used to handle molten steel.

Hard burned magnesium oxide : A second type of magnesium oxide produced from calcining at temperatures ranging from 1000ºC - 1500ºC is termed "hard-burned.” Due to it's narrow range of reactivity, this grade is typically used in applications where slow degradation or chemical reactivity is required such as with animal feeds and fertilizers.

Light burned magnesium oxide (MOC) : The third grade of MgO is produced by calcining at temperatures ranging from 700ºC - 1000ºC and is termed "light-burn" or "caustic" magnesia. Due to the material's wide reactivity range, industrial applications are quite varied and include plastics, rubber, paper and pulp processing, steel boiler additives, adhesives, and acid neutralization to name just a few.

Thank you for this thread. It helped me to realize that the MgO SIPs produced by Innova Eco do not use portland cement: http://innovaecobuildingsystem.com/what_we_offer/. Good stuff.

Andrea Wisner wrote:Thank you for this thread. It helped me to realize that the MgO SIPs produced by Innova Eco do not use portland cement: http://innovaecobuildingsystem.com/what_we_offer/. Good stuff.

These guys are getting their MGO from China since Premier and Martin Marietta do not sell to them. China MGO shipped to the US is usually not "good stuff" so beware...SIPs has issues you can read about in my blog below

hi there... I've just Bern reading this thread... I'm also researching using geopolymer as a binder for hempcrete... we have a local source of kaolin clay... in the process of having some fired to 750deg c to make metabolic... have made sodium silicate from silica gel and lye... going to try this and commercial sodium/potassium silicate to produce geopolymer and add hemp hurd for light weight insulation material... and with Fibre for hard strong material... I have been working with MgO/MgCl Sorel binder which is great but reacts with water...

Hi there.

Curious to the process and results?  I know that hempcrete isn't structural, but any feedback on strength?  There are literally hundreds of journal articles on every kind of geocement.  I always liked the slag cement route, but the closest slag is southern CA.

Also curious as to the concentration of silicate and how it gels?  

I have a bag of type-s currently, ready to test out some pumice instead of the meta kaloin.  And a sample of slag powder and fly ash (ebay!) Just for kicks.   I can find slag locally, but would need to get it ground....looking forward to learning from you.