Bill McNulty’s 2nd Patent — 96 Comments

  1. Hello

    I want to know is the Inorganic cementitious material used in the masonry making like brick in the industrial scale?

    Best Regards
    Hadi Marvi

  2. As for diatmeous earth, make sure you get the natural kind NOT the type for pool filters. Apparently this has already been treated with soda ash and says
    “Natural or dried diatomite generally contains very low percentages of crystalline silica. Diatomite produced for pool filters is treated with high heat (calcining) and a fluxing agent (soda ash), causing the formerly amorphous silicon dioxide to assume its crystalline form.”

    “Amorphous” seems to be the key word here. Whatever is used needs to be amorphous to change shape/texture/chemical balance or whatever, in order to morph into rock

  3. None of the samples that I soaked in a plastic water filled pail stayed solid :( Im going to wait awhile before trying anymore…..

  4. Today I put one of my original stones (not sure if it was made out of the pool salt or the soda ash) into a pail of water in a plastic bucket to soak.

    Today I made another cast, this time I did use soda ash and my ground soil. I did notice the bottom of the plastic pail got immediately warm when I added water. I just put enough water to barely get the mixture workable. I used 20% soda ash and tamped it. I put a plastic pail over it to cure.

    The plastic shopping bag mixture still is soft, so I tore a small hole in the top of the bag.

  5. I don’t think I have any limestone around me for miles. We do have clay, and different kinds, so possibly some kaolin, but not sure.

    I’ve seen diatomaceous earth for about $.50/lb.

    So, am I just out of luck on this, or should I start taking samples of the local clays and try and identify them? Are there other recipes that might be available to those of us without sands and/or limestone?

    • ok, identifying the rock we have here (we have loads of it!), it seems to be Rhyolite, which is high in silica, so possibly a potential ingredient. The clay/silt that it is surrounded by and forms our soil is probably powdered Rhyolite.

      So, I guess I need to find/make some lye and calcium carbonate (hard part, cause I don’t find anything locally).

      • Is rhyolite one of the recommended stone types? I’m busy and loosing track. There’s also another recipe I’ll be publishing soon that uses other ingredients.

    • You only need a few things such as diatomaceous earth. So if you have that then you’re on the home stretch. Keep studying the recipes and see what you can use.

      I talked to a professor yesterday who’s going to help track down local materials. I have no idea where to locate most of these things. We have limestone mountains, but finding a good spot with plentiful loose limestone that’s not on national forest and where the owner is willing to sell, etc. would take a lot of time to find. He thinks he can find me a source of kaolin clay, one of the key ingredients.

      • what recipes should I be studying? I’ve only seen one or 2. I haven’t seen recommended stone types, but I guess I am not looking in the right place.

        DE is great, and I have a little bit that I use for worming animals and keeping ants away from the beehives, but I don’t have nearly enough to build a house! DE is pure silica, but rhyolite is very high in silica as well, but who knows if it is available for a reaction.

  6. Now Im really confused about granite. McNulty says that his system works with “calcium carbonate rocks” but he also says his system works with granite. The problem is that granite is not a calcium carbonate rock like limestone is and this is the reason my soil samples do not bubble much when I added vinegar nor when I added water to my sodium ash/dirt mixture but Owen’s mixture did bubble (very dangerously too)…. comments please?

    • He has two patents — one for calcium carbonate rocks (patent #1) and harder stones like granite (patent #2). Granite won’t bubble like calcium because it has a different chemical makeup. Mine bubbled because I quickly added hot water. It was actually a hissing sound, not bubbling as in gas being released.

  7. Here’s a quote from the article LeissKG sent. This is the version from the NY Times.

    “Dr. Barsoum and his co-workers analyzed the mineralogy of samples from several parts of the Khufu pyramid, and said they found mineral ratios that do not exist in any of the known limestone sources. From the geochemical mix of lime, sand and clay, they concluded, “the simplest explanation” is that it was cast concrete.”

  8. As far as finding out if the soil at a particular site has calcium carbonate (which was the needed mineral along with soda ash, as said by Mr. McNulty), I have read all you have to do is put a scoop of it in a cup and add enough vinegar to cover it. At first look at it every 5 minutes or so and then after 24 hours. If it bubbles that means it is calcium carbonate which is supposed to be the most proliffic rock on earth……

  9. While looking for further information about geopolymers if found the following page While it does not contain much information there are two useful info bits.

    1. a basic recipe by Prasad Boudreaux who worked with geopolymers fund at

    2. a link to the work of Dr. Barsoum ( ). While Dr. Barsoum thinks that parts of the pyramids are cast his research led him to believe that the base material was not clay but instead diatomaceous earth. So if you can get diatomaceous earth for cheap you can cast your own stones. He claims that he has an recipe for stones that survive submersion in water for two month before their properties degrade.

    Klaus Leiss

    • More great news from LeissKG.
      1. I copied this recipe and will post it on the blog at some point. It would be great to know if rice hull ash can be replaced 1:1 with fly ash.
      2. Diatomaceous earth is very common. Do you know the recipe? Is it primarily diatomaceous earth with some sodium carbonate added?
      **The cast stone we’re talking about only has to be reasonably hard. It doesn’t have to be as perfect as the pyramids (= probably ideal materials and a formula derived from years of experiments). And it doesn’t have to be as perfect as Pyrament, which is the super strength geopolymer cement used to patch airport runways.

      • The recipe of Prasad Boudreaux is unclear to me in the part of mixing in the sodium silicate. Either it is sold in a solution of a know concentration or some information is missing. But the recipe is basically the same as is found in point “3.2.2. Alkaline Liquid” of the document “curtin-flyash-GP-concrete-report.pdf” mentioned above. In it is also stated that adding sodium silicate yields a faster and more thorough reaction and according to the curtin document it is cheaper than sodium hydroxide.

        Regarding the fly-ash to rice hull ash percentage I think it was 1:1 but I have no sure information. But since fly-ash can be used in many different concentrations it should be no problem. The only problem I can see is that if you use not enough the resulting stone may be slightly caustic.

        The recipe of Mc Nulty is the only case i read about in which the alkali is not used in an solution that is mixed to the aggregate. Chemically i see no reason that the soda ash should be mixed in dry but maybe Mc Nulty knows more than i. But one more test and you know more.

        I have not found many information on Dr. Barsoums recipe but In the document he writes “We can now make reconstituted limestone starting with sodium hydroxide, limestone powder, Diatomaceous earth and a small amount of lime.”

        Compacting the resulting mixture seems also play a beneficial role in the quality of the resulting stone.

        Klaus Leiss

        • All these comments are being archived for future reference. There’s a lot to remember.

          McNulty’s method: it seems best to combine the dry ingredients together first so they’re thoroughly mixed. Once you add the water it heats up very fast and so you want to stir quickly and use immediately.

      • My mixture never bubbled like yours did. I did a test of my ground with the vinegar though and got few bubbles….. so Im thinking it is the wrong kind of dirt and when I do the water test it wont hold together

      • LeissKG, what would be the difference between “limestone powder” and “a small amount of lime”? Would that be lime type S and limestones?

      • As Owen said. Lime is made from limestone. Type S is made from a certain kind of limestone and has different setting features than other limes.

        Did i know this beforehand? No, I did only know lime is made from limestone and a rough understanding how that is done. The other information came from a quick Google.

        Most of the information i post here is derived the same way. I have no advanced knowledge of geopolymers. What i posted was basically read somewhere on the internet, found through a series of Google searches. I was curious about geopolymers before, but had until now not found the right Google search term. The information that Owen posted enabled me to find the other information. I think what you and Owen is more valuable. You are actually doing something.The only thing that would make it better would be documenting your results. I know both you and Owen know now that it is essential to take notes, but publishing this notes is even better. Until now most information i have found was rather vague, probably out of commercial interest. The comment section of this thread is not an ideal repository for this information because the information is presented in an more or less unstructured way and not easy to follow. Transferring it to a website like Appropedia would probably a good idea. I could help you doing that if you are interested. I mentioned Appropedia because some of its articles are translated in other languages used in less developed countries, while Owens blog reaches only the English speaking community.

        Klaus Leiss

        • It’s all valuable. Your comments and others have helped me. Eventually everything will be worked out and the details published on numerous sites. That’s what we’ve done so far.

      • Leiss, although I do agree the way the blog is laid out for something like this ……. it IS confusing. Not only in this thread but also in the other threads on this site having to do with geopolymerzation. Ive taken to making a folder just for this on my puter, in the folder I have several text documents going with ccp from different sites and the website. I have a page for magnesium cement, soda ash cement, phosphorus and my own tests as well. Im trying to follow everything I can on this blog but Im finding Im having to skip around to a bunch of different pages here as well as the net. Wiki is a good resource for finding out what all these high tech words and symbols mean too. I super super appreciate your reading and keeping informed and posting your found info! There is sooooo much info on this on the web that the more people who are doing this like you, help save many hours in research for anyone trying it.

        I have to leave town for a few days and wont have internet access after tonight. Hopefully when I get back you guys will have a real text book recipe for granite :)

      • Excellent! Thank you Owen for putting up the new site! Would it be possible (though time consuming Im sure) to ccp the informative replies that would help to develope this on the new site as well? Again, thank you for all you do!!

  10. Today at the hardware store I bought Lime S but when I asked for Limestone chips or small rocks, the people there looked at me like I had 3 eyes….. they had no idea what I was talking about and said they didnt have any. I did notice bags of “marble dust grout” and small bags of “marble chips”…… Im wondering if I could make a large marble stone? No one knew what I was talking about when I said kaolin either, or even “pottery clay”. I live in a tiny town and it is about 200 miles to civilization. I would really like to try Davidouvits method, but anything I do with it will be strictly experimental.

    I would need to figure out a substitute for kaolin, and I cant get fly ash either.

    If using the Lime to reconstitute a pure type of rock, then it will probably have to be granite or marble as those are what are more available to me……

    • Stores don’t sell rock dust or crusher fines. You have to go to the source — a quarry, sand and gravel yard, cement batch plant that sells ready mix concrete. You want the fine material that’s left over from washing gravel (and possibly sand, too). It’s pretty much a waste product and so it’s usually very inexpensive.

      Learn about your local geology. Not only is it an interesting topic, you’ll soon learn how to identify lots of different rocks and minerals. There’s a decent chance you’ll find what you need along a road cut etc. for free.

      • The redimix cement place here does have sand for $40.00 a ton, but I will check for the small rocks/fines they have and see what it is.

        Strange thing is, this area produces is one of the largest producers of soda ash lol. I live by Trona California haha

        • Try to buy direct. it costs a fortune shipping stuff back and forth, unloading and reloading and packaging… Yeah, you could be the west coast cast stone house distributor!

      • California is really a PITA There are many abandoned mines around here, possibly by scouring some with vinegar in one hand and a cup in another I could find a suitable material for a making a pure rock. The problem mainly where I live in doing that is the environmental protection laws around here are very strict (which is a common cause for the mines closing). It is illegal to take a rock from the wild….. and there isnt any road building going on around here right now. Plus our ground is mostly all flat desert land so there isnt cutting in the hillsides going on either. About 150 miles from me, I do know of an active pumice mine and there are several ghost towns that used to be mining towns.

        My brother was a big boss out at Trona for many years and they were a producer of fly ash because of burning coal. I tried to get fly ash from him several times, but because of strict laws I could not.

        As for the cement companies, they say they dont have fines but they have 3/8″ granite…. and no limestone

        • Find out who crushes the granite. They should have crusher fines.

          Read up on your local soil. I used to live in a place similar to yours. It had limestone, diatomaceous soil, clay, etc. There may be a rancher nearby, for instance, who will scoop up soil with his tractor and provide everything you need for a song.

    • Limestone chips or small rock may be available in garden centers since they sometimes used in landscaping. If I remember right limestone fines are used as an natural fertilizer so they may be also available in an garden center or an farm supply store.

      Klaus Leiss

      • I did buy some garden lime but it cost 2x as much as the soda ash…. I then bought a bag of lime S in hopes that would be all I needed for the fines so the next problem would be locating limestone chips or maybe using another rock chip….??

  11. My water jar test showed my ground has only trace amounts of clay or silt in it. It is pretty much all sand. This is also confirmed by a professional soil test done in my area. Some of the samples I used Sodium Carbonate and some of the others I used a much cheaper Morton Pool Salt just like this Unfortunately I did not label my samples and dont remember exactly which mud patties were done with sodium carbonate and which ones were the pool salt. I’ll have to redo the test and label if I notice a difference when I try to break them and get them water logged. At this time though they all seem the same.

    • It’s good to see standard products that should be widely available. [Edit: LeissKG pointed out Norton pool salt is sodium chloride. This substance has not been recommended anywhere in the geopolymer literature that I’m aware of.]

      Yeah, we need to keep notes. I made a similar mistake. I checked my samples today and found one granite sample is turning to stone while the other one is still loose gravel, at least on top. I think I used tap water on the latter sample but now I’m not 100% sure. Note to self: take better notes. Also, it’s best to test one variable at a time.

      The unwashed sand sample with lots of small particles is turning to stone while the other one doesn’t feel nearly as solid.

      Sand is super cheap and plentiful here and so I’m really hoping this works. Maybe my ‘sandstone’ house will only last 500 years instead of 5,000, but it’s a step in the right direction. A little experimenting with a modest addition of kaolin (one of the key ingredients) could create a workable product for me.

      • Owen that are encouraging news. If it is stable in water you have at least an cheap foundation material besides ruble filled bags for projects where cost or availability of the soda ash is an problem. Another possibility i see are pavers and
        roofing materials. A water resistant plaster would be nice, but i dont know if the mixture is ductile enough or bonds well enough to be used as plaster.

        In the PhD thesis of Xu (Geopolymerisation of aluminosilicate minerals) available at the University of Melbourne ( it is stated that all aluminosilicate minerals seem to work with the Davidouvits recipe (mixture of a sodium/potassium hydroxide solution and an sodium/potassium silicate solution).

        At least with the Davidouvits recipe fly-ash is an possible admixture. Since fly-ash in many parts of the world is still a waste product you may able to get it cheap. In many parts of the world rice husk ash could also be used. From what i have read the burning temperature would have to be controlled for the latter ( about 700°C max. )

        Another factor in the quality of the result seems to be the temperature. Maybe you could try drying under a black foil if you have a sunny climate at the moment.

        Morton Pool Salt is pure NaCl, I have not read about it in the context of geopolymers. If you get a hard building block with it, you will have to keep it dry, since it is normally water soluble.

        Klaus Leiss

        • Thanks for pointing out the error about sodium chloride. That’s just salt! I went back and edited my previous comment for clarification.

          Gravel bags will most likely always be cheaper and faster than geopolymer. And gravel bags provide a moisture break to prevent water from wicking into the wall. But maybe advancements in this field will usher in total geopolymer solutions. That would be the strongest.

          Geopolymer would make top notch pavers with the right mix. This could be a good way to make interlocking bricks. Seems much simpler than extracting geopolymer CEBs from a press.

          I have a lot to learn about geopolymer, but at this point it’s hard to see it being used as plaster except to fill small areas like recesses between bags. Plaster needs to be smooth and creamy for workability.

          And a big Thank You for reminding me about fly ash. Duh. This is one of the most abundant materials here.

          I hope to avoid products that have to be cured in a special hot area, except for special products like bricks or pavers with high value. That would mean extra time and effort. Much easier to build directly on the wall and you’re finished.

      • The pool salt was just an experiment, as it should be more available in more places and is cheaper. As I said earlier, earth building usually has to be kept high and dry anyway so I thought this would work in the poly bags….. now however I am not so sure because of the formation of crystals on the plastic shopping bag and because it is taking the shopping bag so long to dry out compared to the patties that have already dried out.

  12. My sample in the shopping bag is still soft and spongy, kinda like playdough. However, the samples I left to dry out in the open are very hard now. All of the samples, even the ones made with pool salt will support my weight on them… even the smallest rock size samples and the pieces that broke off from me testing them earlier. I mixed the sodium dry with the dirt and then added water. I did not control the water and by cement terms I would have added way too much. It was a soup consistency and then I scouped out the saturated dirt/sodium mix from the bottom of the bucket before forming the mud patties. I want to wait a few more days and then try to break them with a hammer or something, as well as soak them in water to see what they do. Right now though, I would say it is looking promising!

  13. I look forward to your limestone blocks! They are beautiful in the video and Im sure would make a fine home for anyone. Stone is cool when it is hot outside and warm when it is cold outside.

    As another twist of coming full circle, on your post about the pumice and scoria I have learned that pumice contains mgo (magnesium oxide) and the lime you spoke about contains a lot of magnesium oxide as well. This is the main ingredient in magnesium cement, maybe if some Espsom Salts were added to pumice and lime it would be one heck of a bomb shelter lol

    • I made four small samples a few hours ago using 30% sodium carbonate. My main reaction is the health risks. I used hot water from a kitchen water heater. The mixture hissed as I added spoonfuls of water. The mixture heated up really fast and the plastic container started melting. It burned a hole in my thick leather work glove. Residue seemed to get on everything — the spoon, the rim of the bowl. Some got on my hands and it was hard to get off. Just a tiny bit of sodium carbonate powder floated in the air and now my lungs feel a little strange. It’s really strong stuff. I think it would strip paint and strip grease and burned food off restaurant grills.

      I tested unwashed sand, washed sand and two different kinds of granite fines. I cast the stone in 5″ long pieces of PVC pipe after wiping clear shoe polish on the inside surface. I lightly tamped the mixture with a steel rod to settle the ingredients. The samples are sitting on an earthbag slider (so it doesn’t destroy our table), and wrapped in plastic bags to slow drying.

      And to add to your comments about stone homes in hot and cold climates. What you say is true up to a point in mild climates. In cold climates the stone would need insulation on the outside. In hot climates you’d want to shade the walls.

  14. I will continue to read up on the Davidouvits method and Terrazyme and PolyPavement as well. I was kinda turned off Davidouvits method when I started reading “fly ash” everywhere and that was why I ventured off from his ways. But in his video I didnt notice any use of fly ash, but making that stone he did would probably cost me around $40 or more for the limestone and lime.

    • I’m starting to come full circle back to Davidouvits method because there’s far more documentation and you only need about 5% binders. Fly ash isn’t needed, that’s just one of many possibilities. The recipe in the video looks like a winner to me even though there’s a waiting period for the water to evaporate. I’d rather make two big pits and rotate back and forth than pay a ton of money for binders. The most important thing in my opinion is keep the cost low so it’s affordable to millions. I don’t want this to be some sort of high dollar specialty product for the rich. Again, if the Egyptians were able to do it with simple, locally available materials then I see no reason we can’t figure it out, especially with all the documentation out there.

      • In the document ltgs.pdf they mention that the CORDI-Géopolymère institute has decided to reveal this technology and to explain how to manufacture it for FREE. From context it sounds they mean FREE in the sense of no license paid. They state that the process is not for the layman. Let me cite them “The person who wishes to manufacture LTGS bricks needs chemical and material science backgrounds because it requires some equipments and to develop – invent the right formula for each lateritic soil.” I do not know if you can get more information from them without paying them. They may be right with their statement about LTGS bricks and getting optimum conditions, but most persons at this forum would probably be happy if they get a more stable material or at least something that does not wash away under adverse conditions like a flood. I also think that they underestimate what a layman can achieve with a decent crib sheet. It may require an laboratory analysis of the earth or a sequence of tests with different recipes to get a good enough result but it should be doable if the main ingredients of the process are known. And if it does not work for the earth at your site, what have you lost aside from some dollars for chemicals and some time.

        Klaus Leiss

        • I was just reading about using laterite for making geopolymer. This seems like the most difficult option and may very well require lab tests. I was going to post a summary and basically just gave up. There are too many unknowns.

          The best system I’ve found so far is the one Davidouvits shows in his video. It only uses about 5% binders.

          I think McNulty’s process lacks documentation, requires excessive percentage of binders and has health risks (burns, inhalation of powder, splash.)

      • The only source that contained recipes that one could start with was
        curtin-flyash-GP-concrete-report.pdf. Although it discusses fly-ash based geopolymers it also contains the following.

        “On the nature of the source material, it was stated that the calcined source materials, such as fly ash, slag, calcined kaolin, demonstrated a higher final compressive strength when compared to those made using non-calcined materials, for instance kaolin clay, mine tailings, and naturally occurring minerals (Barbosa et al. 2000). However, Xu and van Deventer (2002) found that using a combination of calcined (e.g. fly ash) and non-calcined material (e.g. kaolinite or kaolin clay and albite) resulted in significant improvement in compressive strength and reduction in reaction time.”

        I think the recipe that they use is good enough to make a start. A point that i read in some of the geopolymer patents is that the medium ( clay etc. ) should be dry. I assume that is to get precise formulas that work. Damp earth may require a stronger solution since it will be diluted by water in the earth.

        Maybe it would be better to start with an artificial aggregate made from sand and clay powder from an art shop and transition to the real thing when the basic mechanisms are known. Probably best is to start with clay alone since if I understand the information right sand is not part of the reaction. So after you get a stone from clay you could add sand to the recipe until it does get to brittle.

        When you have the recipe you can test the earth with the sedimentation test used for CEB making to test if your earth contains enough clay. But will still have to try a series of test samples with different slightly different recipes since other minerals besides clay and sand in the earth may throw the process off.

        Klaus Leiss

        • I looked at the Davidouvits book in Google books last night. It’s 99% advanced chemistry and of little use to average builders. But there are a few gems. He said the kaolin component was the most important.

  15. I think Im going to start experimenting with magnesia next… this salt thing has lead me into all different types of directions lately. I found this page which gives 3 recipes for magnesium cement Last night I mixed an equal amount of soda ash with Epsom Salts (magnesium sulfate) and then water. I let it drain in a paper coffee filter over a glass. The water in the glass is clear but the coffee filter is rock hard as is places that I spilled the emulsion. It cleans up with water (so not water proof). The main paste wad/ball of it is still drying out.

    • Magnesium cement is expensive (not sure how it compares to sodium carbonate in your area). It’s difficult to get the right mix and it’s often not available.

      I suggest switching to Davidouvits method. There’s lots more documentation on it and tons of references to his work. There’s almost nothing on McNulty’s method, which may mean his system has flaws.

      Or use something like Terrazyme or PolyPavement soil stabilizer made from, I believe, fermented fruit.

      • Yes it is expensive…. I want to play around and see if I can make a poor man’s substitute for it. Epsom’s Salt and Milk of Magnesia is pretty cheap here in California. I would think these are products that could be found everywhere for cheap? Maybe with the addition of sodium.. It may completely fail too. As for the fermented fruit, I briefly read that you were getting ready to do a post about it and am anxiously awaiting. I did come across one lead about the fermented fruit, but didnt follow it yet. As for the chernobly, I will try to dig that link up again. But from my research, the geopolymer totally bonds (not just wraps around like cement does) with itself and many other things to create a really, really solid piece where matter even smaller then water and gas cannot pass through. They are using it to seal up nuclear waste and all kinds of stuff. It’s the ultimate bomb shelter and home.

        • I’m waiting for that person to send me the recipe… If they don’t write back, then someone needs to hunt down how to do it. Homemade PolyPavement could be the least expensive route. It’s not as bombproof as geopolymer, but if it’s 1/10th the cost then most people would prefer it.

  16. Salt is a very interesting thing. There are many references to it in the Bible and historic times. There are many formations throughout the world that were made naturally with salt. Ive read several places on the internet about it being used in underground storage of some dangerous chemicals. At this sight, apparently they even “drill with water” underground storage There are also rock crystals which are based on sodium…..

      • The greatest potential I think is for disaster shelter in the case of harmful gas releases. I read somewhere on the net last night about a structure that was near Chernobyl and built with geopolymer. After the melt down happened it had far less radioactivity in it then was measured at houses miles away……

  17. Tonight I checked the samples again. The ones left to dry in the open air seem to mostly be dry but they seem too brittle…. not like dried mud, but not like rock either. Maybe they just need to set out longer or it would have made a difference if I had tamped them? The one in the plastic shopping bag is still moist but setting up real well…..

    • I think tamping would increase strength. That’s how Davidouvits shows the pyramid building process in his video. Tamping would reduce air spaces and make it denser.

      Concrete cures best and becomes stronger if it’s kept damp. You don’t want the outside drying too fast or the moisture that’s inside can’t escape as easily. So… tamp it, dry it slow in the shade and keep it moist. This should hold true for geopolymer as well as concrete.

  18. Yes, reading around the net it looks like there are many different ways of making geoploymer. But most of them involve fly ash (which I cannot get). The one recipe that I am trying is strictly 30% soda ash (aka sodium carbonate) and 70% of my natural dirt (which is granite, feldspar, etc. in a gritty, sandy form). The percentages are aprox, as I just mixed it in a bucket by filling a hand shovel. I did another recipe as well where I used morton pool salt like at this link,or.r_gc.r_pw.&fp=70eb2fd034f89fb8&biw=1024&bih=630 instead of the soda ash. As of yet, there doesnt seem to be much difference between the soda ash or the pool salt

    • That may be to much soda ash since probably not all parts of the dirt are part of the reaction process. But only experimentation will show if that is good or bad.

      Further reading on Davidouvits site brought me to the document ltgs.pdf it covers low temperature geopolymeric setting bricks. Although they only mention the name for their chemical solution, it is probably a mixture of a sodium hydroxide solution and an sodium silicate solution from the chemical formulas. They mention also the french patent ( 80 20386 ) from 1980 that covers this process and that the process is now free. They also mention that the process has to be adjusted for each soil ( probably only if you want to get optimal results ). They also mention that an elevated curing temperature produces a better product. But from an video of Davidouvits it seems that covering the bricks or the wall with black foil gets a high enough temperature in a sunny climate.

      Klaus Leiss

      • I forgot to mention that according to McNulty’s patent soda ash seems only to work with minerals from the calcium carbonate group ( aragonite, limestone, calcite, marble, dolomite ). I don’t know if common soil contains enough of this minerals for this process to work but I doubt it. So it should probably be added.

        Klaus Leiss

      • It would be great to read some reviews of Davidouvits’ book. Is it something average people can use or is it all advanced chemistry talk? Obviously we need more than the bits and pieces scattered on the Internet.

      • Thank you! I will try less soda ash in my next batch and I will tamp it out in a poly bag to see what happens! Im pretty excited about the possibility of homemade cement and have stocked up in the last couple days with garden lime, diametous (sp?) earth, a calcium hardness increaser, natural iron and zinc fertilizer and a few other things. It would be great to be able to mix something with regular dirt and come up with a curable type cement on the cheap and easy rather then from a company working where money is not so much of an object but time is. If the Egyptians did use cement (which the evidence is pretty compelling), they did it out of normal everyday things. One thing I dont have access to is a mining company with limestone…. though pumice is mined not too far away. Even sugar may be a possibility. I think the Egyptians had copper too, and very HOT summers. It is entirely possible the water was heated in copper to mix with the cement, maybe to the point of boiling. That would certainly make sodium or sugar disolve before adding in ground limestone (or hopefully other kinds of minerals/dirt).

        I posted a link I found last night about making magnesium cements. This has been around since before portland cement. But never caught on because, the original recipes were not waterproof and then portland was discovered and cheaper to make. They have now perfected the magnesium cement to be water proof, gas proof, etc. (a very solid bond) It seems to me that since earth building is seldom waterproof anyway and in earthbag building the mixture is protected from water….. that even the poor man’s magnesium cement which isnt waterproof, would be good for people to protect them from all the nasties in the air now and to come as well as to make their homes a bomb shelter. I might be way off on this, but from the last few days of research this is what I am coming up with. Using the sodium was just one of many ways to make a hard bonded crete at low temperatures with natural materials.

        • I’m inclined to follow standard recipes at first and then see what happens. It could take dozens or hundreds of random experiments to hit upon something that finally works. I’ve finally obtained some materials to start testing later today.

          Making magnesium cement is a possibility I hadn’t thought of. I’ll go back to the link and see what’s involved. I know magnesium cement is very good, but the price usually makes it unaffordable. Using truckloads of it to mix with earthbags definitely isn’t affordable.

          I’ll be posting a new recipe soon.

  19. Slowly reading through the material at Davidouvits site I found a document that talks about “LOW-CALCIUM FLY ASH-BASED
    GEOPOLYMER CONCRETE” ( curtin-flyash-GP-concrete-report.pdf ). While the article mainly talks about fly ash, it is also mentioned that kaolin clay works with process but the result is weaker. So depending on the earth at your site it may also work in earth bags. In this article they did not use sodium carbonate, but instead an mixture of a sodium hydroxide solution and an sodium silicate solution ( water glass ). They also mention that at room temperature the curing starts after 24 hours.

    Klaus Leiss

  20. I thought it would be cheaper too. Of course if you can get good strength with a 20% sodium carbonate mix, then a ton would go a long way. 1/5 is not that much. I would also imagine that if a bulkier insulating material was also placed into the mix, the material would go further.

  21. In the document Lehnerv18.pdf on his website he suggest that at Giza a mixture of
    20-30% Natron and 70-80% limestone dust and chips were used. This is a bit more precise than in his patent and should allow first experiments.

    Klaus Leiss

  22. In more research I have found that the trademark “Conch-crete” was abandoned by Mr. McNulty…… so I presume he either passed away or had ideas for the product but then later did not follow thru for whatever reason…

    • That’s good to know, thanks. We need to learn a lot more. The Davidouvits process is much more widely publicized. Maybe McNulty’s process works to a degree but has major flaws…

    • Great! I was able to get a few useful bits of info. It would be great to have detailed manuals, test results, etc. I used to look for things like this at the US Military Academy online libraries. Not sure if these things are available to the public any longer.

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