Archive for May, 2011

I consider yesterday’s blog post about making cast stone earthbags one of the most exciting developments in earthbag building. This newer, simpler geopolymer process sure seems like it will become popular. It sounds like a million dollar idea to me. I imagine millions of people would love to live in an all natural, affordable stone home that’s simple enough to build that anyone can do it. The building process is nearly identical to typical earthbag houses (which is rapidly gaining in popularity) except the fill material in the bags or tubes turns to actual stone. Yesterday I discussed how granite, basalt, sandstone or schist houses could be built. Bill McNulty, the inventor of the stone making process, has an additional patent that uses minerals from the calcium carbonate group, including aragonite, limestone, calcite, marble, dolomite, etc. to create an even wider range of stone homes. What’s not to like?!

Let’s briefly discuss some of the benefits.
– only two materials are required (stone dust and sodium carbonate) plus water
– materials are readily available at many quarries, sand and gravel yards, and cement batch plants as rock dust or crusher fines
– materials are low cost because they’re ‘reject fines’ (gravel is much more costly)
– bonding process begins immediately after adding water (no soaking materials in a pit and waiting two days for water to evaporate)
– good potential for thinner walls that use fewer materials and take up less space because cast stone is stronger than tamped earth
– easy to shape a keyway in the top of each course so earthbags lock together (increased perpendicular shear strength)
– barbed wire not required except in seismic areas, and for domes
– less tamping likely required
– good potential for natural fiber bags
– good potential for lower cost, lower strength bags since bag strength is less important
– bags can be tamped flat on the sides to greatly reduce plaster work
– bags can be cut away and recesses filled with the same material as the walls (geopolymer cement)
– walls can be sealed with wax to prevent build up of salt
– the process is going to be tested on powdered concrete rubble to provide housing in disaster areas such as Haiti (an earthbag team in Haiti has already been contacted)

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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, www.rosetjau.com

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.

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Integrating Shelter, Food, Water and Sense of Place

Integrating Shelter, Food, Water and Sense of Place

The $300 House design competition has about 300 affordable housing projects to study and learn from. I found Kevin Songer’s Integrated Shelter project, and even though it’s borderline genius, it’s way down the list. He entered the contest shortly before the deadline and so most people haven’t seen it. Quick summary and then I’ll let Kevin explain: 800 sq. ft. hoop house for $300. Folks, this thing costs 37 cents/sq. ft. How’s that grab ya? There are lots of clever details that can only be discovered by reading through his whole presentation. It’s one of the few designs in the contest I’d actually consider building. I absolutely love this design and hope to incorporate small versions with my designs.
**Be sure to watch his video. I couldn’t figure out how to upload it here.**

“Critically important to the Urban Core population, food is becoming more and more expensive. Producing maximum quality food in quantities capable of providing for a family can be successfully achieved when permaculture design principles are integrated in.

My final design for the $300 home is based on years of work in developing a low cost, lightweight and affordable living roof and wall system to feed the Urban Core, clean stormwater and restore biodiversity to the cities.

The end result is a place one can be proud of, 75 square meters overall in total, about 800 SF. The front living area is approximately 500 sf, the greenhouse/
shower area is 200 sf and the poultry house is 100sf.

The frame contains 4’ sections of 2” fencing pipe placed 12” in the ground with a small amount of concrete. 1” electrical conduit is placed in the top open end of the pipe and bent in an arch until the opposite end slides into the opposing anchor pipe. Once the arches are up, galvanized fencing is attached to the frame creating a skin covering.

The roof is covered with a heavy duty tarp that can be rolled up for ventilation. The living area, greenhouse and poultry house are separated by walls with a fencing skin also.

Rainwater is collected in a gutter that runs along a knee-wall and stored in an underground cistern. Water is pumped via hand pump to a solar shower bag that feeds the sink also. Drain water flows to irrigate the plants in the greenhouse and then water the poultry.

Living roofs and living permaculture walls line both sides of the home, creating privacy and delivering much needed food. The green roofs are soilless and based on an extreme lightweight design (see photos).”

Kevin Songer’s website
Kevin Songer’s blog
Twitter follow
World-wide green roof plant

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Our family goes about life doing what needs to be done and things generally work out okay. There are ongoing challenges, of course, but we just deal with things as they come. In other words, we have a good life based on a can-do attitude and successfully learning how to deal with things. Seems simple enough to me.

So I was somewhat taken back by all the negativity on the recent $300 House design competition. Most people there are caring, good people who want to find sustainable solutions to help the world. That type of attitude and those kinds of people are what attracted me to the competition. I’ve seen my share of bad behavior on Internet forums, but by entering the design competition I suddenly found myself in the middle of things (in the crossfire), and this has made me increasingly aware of bad attitudes in the larger world. You’d think a competition such as this would be the last place to attract naysayers and people with ill intent, but alas, they seem to be everywhere.

One common theme I kept hearing was people saying “this won’t work”, “it’s too hard”, “it’s too difficult”, and so on. Well, you know what? Everything worthwhile is challenging and takes time and effort – school, work, relationships, even day to day life. So I want to take this opportunity to share some thoughts that hopefully will help others.

Here’s a true story about a man who built his own house with CEBs. You can decide if building with CEBs is “too much work”. (Same basic idea applies to building with earthbags, etc.) I know of a man who was diagnosed with cancer and told he had less than a year to live. He didn’t give up. He quit his job, moved to the countryside, bought a CEB press and built his own house by himself. He immersed himself in the rhythm of the work and quit worrying about things. He’s still alive about 12-15 years later and has built several other houses. (Not to belittle him, but he was weak and skinny from never having done physical work.) So if one guy with incurable cancer can do this, why can’t you?

So I’m saying building houses is a lot of work no matter how you do it. You need to develop a good can-do attitude. Learn as much as you can before starting and never give up. Build small, simple, pay with cash and add on later. If you can overcome the difficulties of building your own home for a few months or so then you’ll have a home for the rest of your life that’s paid for, while most everyone around you blows 1/3 of their working life to pay off a mortgage. (And many of those people will default and lose everything, but that’s another topic for another day.)

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We’ve been discussing Professor Joseph Davidovits cast stone research at the Geopolymer Institute in hopes of applying this concept to earthbag building. You have to admit the possibility of building a house with dirt cheap, natural materials that turn to actual stone and become fireproof, insect proof, bulletproof, etc. is intriguing. [Update: two people have emailed and said they are already building geopolymer earthbag homes.] Just one aspect alone – the desirability of a material that lasts for centuries – well justifies the time and effort to learn more about this subject. We know the basic science of geopolymers is sound. About two hundred labs around the world are working in this field and developing a wide range of products. My new Geopolymer House Blog has extensive information and daily updates.

Let’s think really big for a moment and try to imagine an ideal fill material for earthbags. We’ve already mentioned the desirability of using low cost, commonly available materials that turn to stone. Check. Now imagine using waste materials such as fly ash, slag from iron ore processing, and tailings from mining. Check. (Scientists are already doing this.) Imagine a material with little or no shrinkage when it dries. Check. Imagine a material that uses no Portland cement, because it’s rather expensive and a major cause of climate change. (You can eliminate one ton of greenhouse gas for every ton of material produced.) Check.

Imagine a material that…
– is carbon neutral and doesn’t need a large amount of energy to produce
– can be produced by batching processes similar to those used for Portland cement
– can be applied as shotcrete or by hand
– has rapid set binders
– is resistant to corrosive elements such as sea salt
– is not dissolved by acidic solutions
– has excellent frost resistance and withstands repeated freeze thaw cycles
Check, check, check…

Wouldn’t it be nice to create air spaces in geopolymer with air entrainment additives to increase it’s insulation value? Check. Let’s take it a step further and add scoria, pumice, perlite or possibly rice hulls to further reduce the weight and increase thermal properties. What I’m leading up to is a material similar to pumicecrete that’s made by binding these insulating materials with geopolymer cement. This hasn’t been done yet as far as I know and so the concept needs to be tested, but this general approach could lead to high performance, lightweight earthbag building. Photos show clean ½” scoria and a close-up view showing the porous structure that traps air and improves insulation value.

Small lava rock (scoria)

Small lava rock (scoria)

Close-up of scoria: note porous structure that traps air and increases R-value

Close-up of scoria: note porous structure that traps air and increases R-value

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I think it would be a great idea to start a list of suppliers who sell misprinted bags. Suppliers sometimes sell otherwise perfectly good bags at a discount when the printing quality is not acceptable. Most people use 18”x30” bags, so that would be the best size to locate. Please leave a comment below with the supplier names, websites and prices for misprinted bags that you come across. Also inquire about the minimum order. There may be a 1,000 bag minimum, so that would be good to know also.

Note: Our Resources page at EarthbagBuilding.com has a good list of bag companies who sell misprinted and new bags. My goal here is to expand that list.

I’ll start things off:
Fisher Bag Company Abigail called Fisher Bag Company a few days ago and was told they sell misprint 18×30 bags in bales of 1000 for $.30-.35 each.

Robin sent these companies:
Polytex Fiber Corp
Home page: http://www.polytex.com
Houston, TX
Contact: Denny Smith

Edward Kennedy & Co Ltd
52 Bracken Road Sandyford Ind Est Dublin 18 Co. Dublin
Home page: http://www.edwardkennedy.ie

Company Name: Agripack & Bulk Bag Mnfr
Street Address: Blesbuck ln
City: Reitz
Province/State: Freestate
Country/Region: South Africa
Zip: 9810
Telephone: 27-072-4226627

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WestcliffeDan, one of our readers, left a comment suggesting a “Survivor” style reality show that drops the winners with minimal tools and basic supplies somewhere and have them implement their designs. I instantly lit up and laughed, and think the idea is worth pursuing. It could be used to prototype the winning designs from the $300 House design competition. Or maybe prototype them in Alabama first and then send out building teams once the details were worked out. Any ideas? What seems like a joke could actually make for a good show people would enjoy and learn from. For instance, it would be great fun to watch the University of Stanford students work their way through the nitty gritty issues of building in a developing country. Perhaps the housing team could have a videographer join them and document the process. Profits from the resulting film would help offset their travel expenses.

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