Pretty soon we will demonstrate that we can press 3000 bricks with the CEB prototype two. We have been thinking about our village design. For some time now I was considering earth-sheltered ecotecture, such as this beauty found at undergroundhousing.com:
The only question is, can CEB bricks be utilized in below-grade applications? While as strong as schist or granite when fully cured, the CEB blocks turn into a mudslide when wet. Can we hope to achieve proper water proofing when underground, or do we keep all CEB building above grade? Has anyone heard of CEB brick being used underground? This would be excellent in cold climates, including our own – where earth sheltering could afford zero energy homes. This assumed large earth-moving requirements, but is not a problem in the presence of appropriate, mechanized tools like LifeTrac.
Have you investigated mixing a mortar additive into the bricks to address this problem? I believe that is the key ingredient these guys http://www.ecosustainablevillage.com/compressed_earth_brick_homes.htm are using. They are also using an interlocking pattern to do away with the need to apply mortar. I think I even saw roof and floor tiles in the mix.
This is exactly what we need to be thinking about. In addition to mixing mortar into the bricks, perhaps there might be a way to cheaply improve the quality of the mortar to make it even stronger.
I know that concrete is often mixed with slag, an industrial waste product, to make it stronger. Perhaps something similar could be done.
i hear lime is great for CEB stabilization.
Wouldnt a good thick layer of plastic, outer layers of some mosture resilient plaster, and a french drain do the trick?
I’ve been looking into various CEB stabilization methods and an enzymatic additive is probably the most cost efficient way that I’ve found so far. You mix it with the water used to form the CEB’s and it makes the block water resistant without having to worry about how much cement or lime to add. It’s usually used in road bases to keep the dust to a minimum. The product itself is expensive (around $120 for a gallon) but it goes a long way. I believe a gallon treats about 1000 gallons of water. And since CEB’s don’t need much water, it makes good sense.
However when I asked the manufacturer if this would be a good product to make CEB’s stable enough for below grade work, they told me they didn’t recommend it.
Here are some manufacturers:
http://www.itstoyou.com/internationalenzymes/perma-zyme/index.html
http://www.soiltac.com/
I believe I saw a note about 10 years ago about mixing in asphalt to waterproof earth or concrete slurries (used to prevent water wicking upwards thru it) in use on floors. That might work for waterproofing, although the compression approach doesn’t really fit with adding either a mortar or other additive…if I understand the process. Just my 2 cents.
Lenita, we don’t use water with compressed earth bricks, just compression of dry earth. How would such stabilizers apply to our technique?
A couple of things:
1. I have been thinking about how “waste” plant material from certain species might be good candidates for being pressed into board material, possibly with cellulose extracts as a bonding agent, and with certain candidate material bonded to the outside (maybe even living material?) that will weather/water proof exposed material
2. I wonder if CEB might be able to produce more bricks simply by multiplying the hoppers, rams, etc in one unit? I guess that is obvious, but it just popped into my head while reading this. I suppose there are factors like the speed and work it takes to shovel dirt in (wonder if this might also be more automated). Just thinking out loud here
Sam, I’ve been thinking along the same lines lately. Start pressing in 4×8 sheets, but presses could be any shape, really. They could be nailed, screwed, painted. With the right bonding agent, they could also work as automotive panels, to keep rain off of the tractor and operator, etc.
Please start docuementing procedures for biomass panels on the wiki. I understand that the commercially available Isoboard does board pressing, while also using heat.
Ok, I will document on the wiki as I research/develop.
Also, I still want to talk to you about creating some kind of packaging system for projects. Maybe that is not a priority, but it could help spread the work of fabrication and development. I also have a method I am developing for composing and packaging howtos, that can import OSE wiki pages, pages from other wikis, etc. These how-to’s can be part of a distributed repository/package system.
Also, let us now CAE Linux is working out for you and Jeremy (I know you are a bit busy to blog everything all the time of course)
Moisture barrier and CEBs have to be separate components of this design. A plastic membrane may be the simplest way to get this done (OK we don’t like plastic, alright). Another option is a ferrocement component.
4 layers (+ functions):
– earth (insulate)
– ferrocement or plastic (barrier)
– more earth (more insulate)
– CEBs (weight bearing)
I have been considering CEBs in arched rooms with half-dome ends underground. Another form for rooms would be the groined vault formed by two intersecting arches. These structures would be buried after additional waterproofing and drainage installation. As a civil engineer I work with soil cement and roller-compacted concrete, or RCC. The mix design philosophy for RCC is ideal for high-strength CEBs that won’t fall apart when wet. My RCC dams are in a river and are holding well. Soil cement is on the upstream facing of another dam at a reservoir. Cement stabilized soil mixes should be ideal for an underground CEB structure application.
>CEB blocks turn into a mudslide when wet.
The Auroville Earth Institute, arguably the world’s best authority on CEBs, mixes in 5-10% cement. The CEBs are fine in the monsoon of Tamil Nadu.
link: http://www.earth-auroville.com
Let’s see, 5-10% cement by weight would mean 3000 lbs per 300 square foot space, or about 40 bags of 80 lb. That would be about $150 in cement, or 50 cents per square foot of space. Decent, if we could then go to earth-sheltered housing.
Auroville is where I recognized the crossover between durable soil cement or RCC designs and cement stabilised earth blocks (CSEBs) for underground housing. The mixes are basically the same: 15% gravel, 50% sand, 15% silt, and 20% clay with about 5% cement. Some soil modification may be required based on site conditions and wet-testing strength over time would be required. This besides drainage considerations.
—-
Roller compacted concrete refers to the placement method of a zero slump concrete. The mix consists of aggregate, a clayey portion of soil, a portion of cement, and enough moisture to hydrate the cement. The mix is placed with end loaders and spread out. A vibratory roller compactor then makes passes over the concrete until the optimum density is reached. I designed three small channel dams using this method starting in 1993 and it is used frequently in dam rehabilitation.
Both RCC and soil cement are used for pavements, too. They are very durable and can support heavy loads. The mix is very similar to what would be used for rammed earth and this is where I started thinking of using it for earth sheltered structures. I prefer the CEBs because the form work necessary to rammed earth is not required. There is a wealth of information you may be aware of at http://www.earth-auroville.com/. The CEBs they use have at lease 5% cement added and the mix recommended is similar to RCC or soil cement.
The Portland Cement Association (PCA) has design guidelines for soil cement and RCC available. You can also find the main difference between concrete masonry units (CMUs) and CEBs here: http://www.cement.org/masonry/block.asp. The PCA if focused mainly on producing concrete, but our interest is in using cement modified soil in a compressed, stable form and made onsite. More information from the PCA may be found at http://www.cement.org/pavements/pv_sc_cms.asp, and a discussion on RCC is at http://www.cement.org/pavements/pv_rcc.asp. Most of the information is on pavement design but I see a huge potential in using the pavement design approach to earth construction, especially pertaining to your question on the forum about using CEBs underground. Take a look through the PCA Bookstore’s Water Resources section at http://www.cement.org/bookstore/results_category.asp?store=main&featured=true&id=13. Much of the literature is free to download. If you like I could suggest a few.
But much of the same design philosophy for using an RCC or soil cement type mix can be found at http://www.earth-auroville.com/. The best, shortest info piece on mixes comes from Auroville. They advocate a cement stabilised earth block, or CSEB. Their website is where I got the attached PDFs. Your question on the mix to stabilize CEBs is going to vary by location and soil type. What might be suitable for one location might not work for another. Ideally, the soil on site would be just right for making a CSEB but that is seldom the case. Soil identification is the key and may require offsite testing at a soils lab to determine contents. This and the cement would be an additional cost but one well worth it. The mix proportions as in the attached docs are 15% gravel, 50% sand, 15% silt, and 20% clay. A good cement proportion to use is 5%. I prefer cement to lime for underground housing for the concerns you stated, plus the extra curing time required for lime-stabilised blocks.
The key to keeping an underground house dry, besides waterproofing, is going to be what is placed on the outside to drain the water away. That is a major design consideration. We don’t want the structure soaking in the ground.
I hope I’ve addressed your question adequately. If not, or if I’m offbase, let me know.
Files:
http://openfarmtech.org/1767_alt.pdf
http://openfarmtech.org/cseb.pdf
http://openfarmtech.org/Earth-raw-material.pdf
Check also this:
http://www.off-grid.net/2009/03/09/soilcrete/
About the “waste biomass/plastic” boards,
please check the work of Elsa ZaldÃvar and Pedro Padrósin Paraguay, where they “mix the leftover piecesof a vegetable sponge (called loofah) and recycledplastic to form strong, lightweight panels that
can easily be assembled into simple structures,including houses”.http://www.youtube.com/watch?v=P2PhNaLFtDAI found this from the book “Inspiring Individuals,
Ten People Making a Better World” (The 13th Rolex Awardsfor Enterprise, 2008, ISBN 978-2-9700541-8-4).http://rolexawards.com/en/press-room/photo-downloads-2008-laureates-elsa-zaldivar.jsp
(Sorry, I screwed the formatting and the URL’s in
the previous comment. Please delete it, and use this one instead.):
About the “waste biomass/plastic†boards,
check the work of Elsa ZaldÃvar and Pedro Padrós
in Paraguauy, where they
Youtube-video:
http://www.youtube.com/watch?v=P2PhNaLFtDA
I found this from the book “Inspiring Individuals,
Ten People Making a Better World” (The 13th Rolex Awards
for Enterprise, 2008, ISBN 978-2-9700541-8-4).
http://rolexawards.com/en/press-room/photo-downloads-2008-laureates-elsa-zaldivar.jsp
Thanks for the links Antti and Louie, we’ll check them out some more.
quoting Marcin: “Lenita, we don’t use water with compressed earth bricks, just compression of dry earth. How would such stabilizers apply to our technique?”
Many of the compressed block makers I’ve run across use a *very* small amount of water to mix with their soil. The enzymatic additive is added to this water and it bonds to the soil making it all but impervious to water penetration. It’s effective enough to often be used in the bottoms of lake beds to prevent water loss. I assumed your technique was similar to theirs. I don’t know how effective it would be since you add no water. But since it’s safe to say that there is a minute amount of water in the soil you use, it may be possible to add a very small amount of stabilizer dependent on the percentage of moisture present in the soil. It could be an even more cost efficient solution than cement which we know has its detractors because of how it’s manufactured. Just an idea.
Louie-
Yours is an old post, but if you’re out there, I need to talk with you: http://www.localogy.org/contact
What you posted was very logical. However, think on this, what if you
added a little information? I am not suggesting
your information isn’t solid, however what if you added a title
that grabbed a person’s attention? I mean Solar Village
Underground | Open Source Ecology is a little plain. You could glance at
Yahoo’s front page and watch how they write article headlines to get viewers to click.
You might try adding a video or a related pic or two to get people
interested about everything’ve written. Just my opinion, it could make your posts a little bit more interesting.
How has this project been going? Did you make any breakthroughs and how has the CEB brick worked?