Earthbag Building May be Thousands of Years Old

Bill McNulty believes the base stones on the Menkaure Pyramid were made with cast stone in bags
Bill McNulty believes the base stones on the Menkaure Pyramid were made with cast stone in bags

Major Breaking News. Tim, one of our readers, sent me some information the other day that explained how Bill McNulty has patented the process of making cast stone using natron salt (sodium carbonate) mixed with powdered granite, limestone, basalt, schist or sandstone mixed with water. This is a slightly different method than proposed by Professor Joseph Davidovits (see How the Pyramids Were Built). I finally got around to reading some of the literature that Tim sent. The following passage literally gave me goosebumps when I realized McNulty was describing how some ancient stonework may have been cast in bags much like earthbag building. (Note: Whether or not ancient stones were made by being cast in bags is still theoretical. The main point is McNulty’s stone making process does work. See comment below.)

“The lower courses of the Menkaure Pyramid were created by casting natron [sodium carbonate] and granite in flexible forms. These flexible forms were made from sturdy cotton or hemp cloth and give the lower courses of the Menkaure Pyramid their distinctive shape. After the flexible forms of hemp or cotton were filled with a natron and granite mixture water was added to turn the cementitious material into a solid block of granite. Cement can be purchased today in a similar form called “sling bags”… [Ed.: McNulty thinks wooden forms were used for the rest of the pyramid.]

Over ten thousand diorite balls have been found in Aswan at the site of an Ancient Egyptian granite quarry. Diorite pounding stones allowed workers to pulverize Aswan granite into a dust which was transported to the Giza Plateau on the Nile River. Aswan granite dust and chips were combined with natron and water to produce the granite blocks of the interior chamber walls of the Giza Pyramids, the granite casing stones of the Menkaure Pyramid and granite statues.”
Source: Giza Throne Theory, Bill McNulty, page 12,

From Bill McNulty’s patent application: Cementitious material
“A combination of compositions, products and methods of producing a new type of cement. The cementitious material is created by adding sodium carbonate (also known as soda ash, trona, natron, sodium carbonate decahydrate, sodium carbonate anhydrous, etc.) and one or more rocks or minerals selected from the following–granite, basalt, sandstone or schist. A new method and product are claimed by combining sodium carbonate and one or more rocks or minerals selected from the following–granite, basalt, sandstone or schist and water. The combination of sodium carbonate and one or more rocks or minerals selected from the granite, basalt, sandstone or schist group can be either layered or mixed in a dry or wet state. An exothermic reaction starts after the addition of water to the cementitious material. The composition of the cementitious material can vary between 10% sodium carbonate and 90% of one or more rocks or minerals selected from the granite, basalt, sandstone or schist group to 90% sodium carbonate and 10% of one or more rocks or minerals selected from the granite, basalt, sandstone or schist group. Organic or inorganic additives may be added to the mixture to enhance the composition and/or the final hardened product. The cementitious material or products can be used in a variety of applications not inclusive of forming bricks, interior architecture, table or counter tops, ornaments, repairing damaged cement products, casting, bioabsorbable devices, extruded products, sprayed products, filler, grout, mortar, gunnite, moulded products, composites, cast stonework, agglomerated stone, concrete, hardened products, electronics, packaging and other applications not mentioned above.”
Inventors: McNulty, Jr.; William J. (Provo, TC)
Appl. No.: 10/199,079
Filed: July 22, 2002
US Patents #6,264,740 and #6,913,645

Note: Tim just won himself a free copy of my upcoming earthbag book. Thank you Tim!

How to build cast stone earthbag walls:
So if you’ve read this far you’re probably excited about the possibility of building a cast stone earthbag home and wondering how to do it. I believe I’ve figured out a simple, cost effective solution; however, I haven’t tested the process yet. I recommend using natural fiber bags such as cotton, hemp or linen bags. These fabrics allow water to penetrate. Fill the bags with the necessary dry ingredients in the correct proportions (stone powder and/or crusher fines mixed with sodium carbonate). Stack one course of bags much like regular earthbags, but with dry ingredients. Sprinkle the bags with water until the contents are wet throughout. You’ll have to experiment to determine how much water is needed. Tamp the earthbags level. There will probably be a waiting period for the stone to set up and then you can repeat the same process for the rest of the wall.

It’s also possible that stone powder, sodium carbonate and water can be pre-mixed and put in earthbags just like moist road base or moist soil. But this needs to be tested, because McNulty says the chemical reaction begins immediately after water is added.

Also note, stone powder and crusher fines are often available from quarries, sand and gravel yards, and concrete batch plants at very low cost. Most people want the more valuable aggregates for use in concrete, etc. Stone powder/crusher fines is a low value leftover material.

35 thoughts on “Earthbag Building May be Thousands of Years Old”

  1. Pingback: Bill McNulty’s 2nd Patent « Geopolymer House Blog
  2. Never mind, I just found it in his patent:

    8. A soled product comprising at least one aggregate selected from the group consisting of bedrock, traprock, quartz, quarzite, granite, marble, limestone, dolomite, sandstone, chyrsocolla, malachite, biotite and feldspar bonded with the cementitious product of claim 1.

  3. Im looking for McNulty’s reference to granite and cannot find it. I searched online too about the chemistry of granite and havent been able to find anyone who says it is calium carbonate. My ground has a lot of granite and I have some small granite rocks around, when I added vinegar to my ground I got a little bubbling, when I put a granite rock in a cup covered with vinegar I got no bubbling…… is this a typo?

  4. I’m starting to wonder what the difference is between soda ash and polypavement….they seem to have some similar traits.

    • From what i read polypavement is organic chemistry ( oil based ), some are acrylic based some vinyl acetate polymers, there exist probably other. If you want more information read the Material Safety Data Sheets of the product in question.

      Geopolymers are inorganic polymers

      While soda ash can be synthesized it is also mined and a large part, if not most of soda ash in the USA is mined.

      Klaus Leiss

  5. A lot of soda ash is used in the production of glass. Also, most soda ash is man-made using table salt and limestone, though that’s all I know…not sure how difficult it is to produce, or if it even makes sense.

      • I agree about how most of the details are lacking. It seems geopolymer scientists are focused on technical details and creating high dollar products, not distilling the information so average people can build practical things like houses. So the market for a book like this is wide open with zero competition at this point.

  6. Is there an alternative for barbed wire? The rebar looks nice! Maybe the Egyptians way would be best? Doing rammed earth so the blocks could be bigger and making them with the holes and pegs like a compressed earth block or just doing a ceb with the mixture and using basalt rebar and then coating the outside with wax? Even just using this to line foundation rubble trenches would be nice I think….

  7. In his articles McNulty states that cast stone leaches salt. He uses it as proof for his theory since the Egyptian monuments seem to be the only ones that leach salt. To avoid this the stones has to be coated on the outside. According to his theory the Egyptians used bees wax.

    Regarding the danger of steel reinforcement corrosion. There are coated reinforcement rods available for building in salt water zones.

    Klaus Leiss

  8. Anyone test this stuff yet? I was wondering how water proof it actually is? If it has a fair amount of water proofing and adhesion properties it could be used as a spray or trowel on coating over the earth bags. That would be great for domes and earth sheltered homes.

      • I dont know if it is water proof or not. My samples are all still curing. When they are done curing I will test. It seems the salt seals the grit and it is a slower drying process where it dries from the outside in. I can knock on my patties and they seam hard but the edges I left thin and they easily break. I did my samples more like mud patties rather then in a true poly bag and tamped like one would do for a building. The patties are about the size of my hand and maybe a couple inches thick in the center gradually thining to flat on the outsides (just like when we were kids). It’s interesting though that I have put some in a plastic shopping bag and sealed it, but then had crystals (I assume salt) actually form on the outside of the bag! I have read that it takes about 10 days to cure, Im only on day 1. I did mix 30% to 70% like was in one of the drawings in the pyramids where they say it is a description of the brick builders.

  9. Owen, thanks for your sites – I think I’ve gotten more useful information from these than anything else I’ve read regarding earthbags. I’m still saving money for land/building materials and have yet to play with earthbags, but could the mesh bags work with a geopolymer dry mix and then wet them down? Or would the holes be too big for the dry mix? I’m thinking the raschel might be cheaper to get than linen or burlap.

  10. Im going to play with this stuff, and see what all I can do. But to be perfectly honest, for me it is disappointing as of yet.

    I made a few small mud patties to experiment with. A couple I used pool salt for. Even though they are setting up pretty good, they are leaching salt and one of them I put in a plastic shopping bag (which formed salt crystals on the outside of the bag). I live in a seismic area and most surely would have to use steel reinforcing but would be concerned the salt would corrode the steel rapidly….. even stacked inside bags on a wall for curing.

    Because I have codes where I live, I can only go so far with this. I did think about a driveway or stepping stones, etc. Again my main concern at this point is salt leaching into plants or the air around the metal vehicles.

  11. I got some for experimenting with today. It was a 6lb bottle called PH Up but it cost $9.95 us dollars. It is the only thing I have found at my local grocery store or Home Depot that is 100% sodium carbonate. Everything else the labels said had additives or “improvements”…. Hopefully this can really be bought for cheaper. I did read that baking soda is sodium BIcarbonate and that heated to 140*F it releases carbon dioxide and becomes sodium carbonate. Maybe a few seconds in a microwave would do it? Im not a chemist by any means but it is worth experimenting with because it is wayyyy cheaper then the PH Up stuff…… unless another good source can be found.

  12. I absolutely LOVE this! I want to experiment with it as well. But in my research it seems that sodium carbonate is commonly known as Soda Ash which is sold for swimming pools. Today after work Im going to go price it.

  13. Very cool to know that this might work with granite. Our homestead land is located in an area rich in granite and with many quarries and processing facilities, so granite powder should be relatively easy to obtain locally – much moreso than limestone.

    That said, I have to sort of chuckle at the patent application. Can anyone really claim to be the “inventor” of a 4000 year old technique they’ve rediscovered?


    • I believe most gravel used in concrete is granite. There may be exceptions, but I know it’s very common. Granite is preferred due to it’s hardness and high compressive strength.

      This is very good news for me as well. We spent 8 hours on the highway the other day looking for a limestone quarry without success. But granite gravel fines are pretty much everywhere. Just need to find the best price. So then I’d only need sodium carbonate, I should be able to find that in a major city.

      That does sound funny trying to patent something that was probably used thousands of years ago. I’ll have to let the lawyers sort it out.

  14. Just like Professor Davidouvits provided lots of tantalizing evidence of how the ancients probably used geopolymer, this story by Bill McNulty provides very convincing evidence of cast basalt.

    Evidence of cast basalt: (see photo in the PDF)
    “The basalt platform located near the Northeast corner of the Khufu Pyramid was probably cast with a wet cementitious material… The wet casting method would also explain why the bottom side of the platform fits perfectly to the underlying limestone base. It’s not possible to carve basalt to conform to the limestone base.”
    Source: Open Letter to Dr. Mark Lehner from Bill McNulty, Version 1.8, page 5, December 2010

  15. While I’m convinced McNulty’s stone casting process works as claimed, whether or not ancient stonework was made by casting stone in bags is still just a theory. If bags were used, I can’t explain the uneven shapes unless the stone was dressed while still relatively soft, and the workers were careful not to leave tool marks. The main point, however, is McNulty has figured out how to create more kinds of cast stone much more quickly, using fewer materials and a simpler process than Professor Davidouvits.

    Last week: I’ve been thinking a lot lately about geopolymer and so when I was looking at photos of bulging stonework at Machu Picchu, I considered the possibility they may have been cast in bags. But I ruled it out at the time because Professor Davidouvits said his process didn’t work with granite. No one has ever been able to figure out how this stonework was done, and now McNulty’s process could be the answer. Again, you’d have to assume some dressing of the stone shortly after casting. See bottom photo.


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