CEB Composition & Sourcing Materials

I have purchased a Compressed Earth Block (CEB) press after a lot of research. This summer I will be building a barn with CEB's as a proof of concept, so that maybe I can build a house out of it in the coming years. I am going to put several sensors inside/outside to test how it performs, and also how well it holds up to the weather elements. I live in southwest Virginia, a few minutes from the Blue Ridge Parkway. My family will be setting up a small little farm on 5.5 acres and this barn represents the first step in that process. I don't have to worry about building codes since the barn will be 900 sq/ft and classified in county documents as farm use.

Leading up to my build for this summer I'm starting to source materials; Subsoil, Lime, Cement. The table below gives an idea of where my research has led me in terms of percentages for the CEB material. I know there are mixed opinions on what the correct percentages of each item should be, but this is what I'm settling with unless I hear a good case otherwise (the % table is below). All values listed below are 20% more of what I need to make the blocks & mortar, I'm figuring waste so I don't come up short on any given product. I'm using 2 different stabilizers that work extremely well together only because I want to reduce my usage of cement without eliminating it completely. Moisture content will be roughly 10% when I'm mixing and pressing the blocks. What I'm here to ask about is Lime, Concrete & Subsoil (Clay/Sand/Silt/Fine Gravel).

Subsoil: I can't use the subsoil on my property, way too much clay and large rocks/boulders to contend with, excavation would be costly. The neighbor landscaped/graded his lawn and ended up spending a fortune, I'm not going that route. With that said, I need to purchase Subsoil from around where I'm at, as locally as possible. What type of company would I contact to get a quote? I'm looking to buy roughly 29 cubic yards (Clay + Sand + Fine Gravel), more is fine if it needs rounded off for a truck load. What type of questions do I ask so I make sure I get what I want, i.e. no topsoil, no organic material....etc.

Lime: This area is probably my least understood material in the process. Some use Agricultural Lime (hydrated lime is readily available), others Reject Lime (whatever that is). I've searched each term and very little is talked about in reference to CEB's, at least as to what type of lime they use. I know of a local quarry about an hour away from me but before I call what do I ask for?

Concrete: Still in powder (dry) form when delivered. Do I buy it by the bag or get my ready mix supplier to deliver some? What composition do I ask for? Should I ask for specific ingredients? Volcanic Ash, etc... It's only about 2 cubic yards I need.

Concrete & Lime onsite Storage: My concern, it will get wet from rain potentially (probably) before I use all of it. Even a canopy wouldn't do, we can have good thunderstorms at times where the rain comes in from the sides. So am I going to have to use a tarp in those conditions directly on it? And wind, I don't want it to fly away. I also don't want ground moisture being drawn upward into the piles and then when I get to the bottom I have an impossible mess to deal with. Once again, maybe a tarp to put each product on and a tarp to cover it with stakes at each corner and only uncover when I need to draw from the pile. Better plan anyone?

............................................cubic yards
Clay...................... 20.0%...(6.517045791)
Sand..................... 68.0%...(22.15795569)
Fine Gravel............ 2.0%.....(0.6517045791)
Lime...................... 4.0%....(1.303409158)
Portland Cement .... 6.0%.....(1.955113737)

............................100.0%

All these problems didn't occur to me until I started to build everything in my head and on paper. Now that I have a CEB Press I need to get things in action. I'd like to have my bill of materials by the end of this month so I don't run into any situation where it might take a while to get a product sourced or located.

Thank you for your help.

Ryan

Hi Ryan,

That's a big question, so if I don't remember every part just ask again.

Subsoil- Excavation companies that dig out for foundations etc. usually have extra fill available at a small price, but this is not going to be graded, so you will still have to process the material. There's a lot to this part, depending on the soil and what the stratification test shows. The modifiers added to the soil will vary according to soil type, so we need the soil tests before final acquisition of materials.
Lime- Hydrated lime is best and can be purchased inexpensively.
Concrete- Concrete is a cementitious mixture typically utilizing Portland Cement as the "glue" for the aggregate. You just want the Portland Cement, in powder form with nothing else added.
On-Site Storage- I typically buy these goods on a pallet, either in 50-80lb paper bags or 1 or 2,000 lb super bags. I save the plastic covers from the pallets of wood pellets that I heat my house with in order to cover these kinds of things. The other materials are typically stored on the ground loosely covered, but hydration ratios must be adapted to the amount of water absorbed by the sand and clay. A bulking test can tell you quickly about how much moisture is present, or just know your mix.

You have probably already heard about these guys, but in case you haven't; earth-auroville.com

This should get you started, Bill

Dear Ryan,

Did you end up building your house?  I am soon going to build a CEB house in the same region, and would love to hear how yours went.

I know your post was from ten years ago, but I thought it was worth a shot in the dark! Thank you!

Molly,

I can share my experience. Just ask questions.

Thank you very much for offering!

Here are some of the questions I have:

Did you use stabilized or unstabilized blocks?
Did you dry stack interlocking blocks or use mortar with non-interlocking blocks?
Did you have an alternative support structure (we are planning for post and beam), and if so, how did you connect the blocks to your structure?
How tall is your stem wall and how deep is your eave to protect the walls?
What kinds of equipment did you use for the sifting, mixing, and block production?

Thank you again!

Did you use stabilized or unstabilized blocks?
With the correct soil mixture which often occurs naturally, no stabilisation is needed.

Did you dry stack interlocking blocks or use mortar with non-interlocking blocks?
Mortar made from the same material as the bricks. No additives.

Did you have an alternative support structure (we are planning for post and beam), and if so, how did you connect the blocks to your structure?
Post and Beam is smart, it gives you a roof to work under. Barbed wire or mesh laid in the courses can be attached to the posts.
Consider steel posts,  since they are lighter to handle, dont rot and easy to work with.

How tall is your stem wall and how deep is your eave to protect the walls?
Fired bricks are best used as the first layer above the floor height.
Eave width local knowledge is best, but direct rain needs to be kept off the walls.

.What kinds of equipment did you use for the sifting, mixing,
often nothing

and block production?
Adobe are made with wetter mixtures and moulds
Compressed Earth Bricks are made with moist material and compressed in a Dalrac Mudbrick Press, a Compressed Earth block maker
Arum from India are not the best unit to purchase, a Cinva ram.

Did you use stabilized or unstabilized blocks?
I have used cement stabillized. The vendor was supposed to use 10% cement, but obviously he used less, because the blocks if left unprotected will get eroded within few years. The test blocks that I made with 10% cement survived 10 years left to elements (on the ground) almost unchanged. If using unstabillized blocks they have to be protected very well.

Did you dry stack interlocking blocks or use mortar with non-interlocking blocks?
All blocks are laid on mortar bed (2.8 coarse sand, 1 part clay, 0.28 portland cement) so the course height was 4". The blocks had varying thickness from 3" to 3.5", so even if I wanted to dry stack I could not. Besides that the blocks have ladder mesh and rebars over arches.
The coarse sand had particles up to 1/4" size which worked perfectly, because the max aggregate size should be half of the joint size.
I sourced some local clay and bought a truckload.

Did you have an alternative support structure (we are planning for post and beam), and if so, how did you connect the blocks to your structure?
All walls are structural masonry: exterior 24" and interior 16". Reinfoced with vertical 0.5" rebars (and grouted) on the interior and exterior side of the wall and with ladder mesh on each 3rd course. Connecting anything to CEB blocks is challenging, because they do not want to hold normal masonry anchors. For windows and door frames I used all-thread rods with drilled and threaded holes, so I could set them in resin in the wall and screw the frames to them. If I built again I would pour concrete in place of blocks, in places where I planned to attach anything serious. Some people use wood pieces in such spots ("gringo blocks"), but I would prefer concrete, grouted concrete block, solid bricks or a stone ashlar.
If I had to connect to a wooden structure I would first screw in the anchors (L or J shaped) and bolt them with nuts and large washers to the posts and beams and then in these spots where the anchors protrude I would pour concrete in the place of blocks. The same concept, but in reverse is used in my roof structure: stainless anchors (fi 5/8") were set in concrete bond beam first and then top plates and rafters attached and bolted down.

How tall is your stem wall and how deep is your eave to protect the walls?
I live in a warm place, so the footings are 12" deep and 6" above the ground, so total 18". My eves (brick cornice plus roof tiles) are protruding 10". Quite sufficient in my climate. I have not observed any erosion on the walls and the outside is still not plastered.
If you live in a colder place you have to adjust the footing depth to the required minimum. Foundation is something that can not be changed, so please research it.

What kinds of equipment did you use for the sifting, mixing, and block production?
Originally I purchased a hydraulic press. Sifting was a major problem. The soil was brick hard and I had no means to pulverize it, so I purchased a small rock crusher, but in the meantime my blocks were not passing the lab tests for water absorption, so I abandoned the concept of making blocks. If I ever wanted to do it again I would source the materials separately: sand, clay, some cement, mix it and compress it. Sifting my soil was not an option, because I would end with 90% soil "nuggets" and 10% of sifted material. The small rock crusher would not handle the amount needed anyway - but I find it extremely handy in pulverizing solidified clay, bricks, old plaster, etc.


Additional advice:
-Get a simple rebar bender that can bend rebars up to 5/8". It will cover 99% of your bending needs.
-Get a quality block saw made by MK or Imer. It will give you extreme flexibility when building from masonry. Good saw plus angle grinder will allow you to cut any shape if needed.
-Feel free to mix blocks with bricks for some architectural detailing, arches, shelves, cornices; you can lay the bricks on blocks using cement based mortar or pure lime mortar.
-If you plan to use masonry heater, please place the chimney in a central spot and consider having a separate chimney to heat the bathroom. Plan the foundation for the heater.
-Try to locate all water related rooms in one corner of the house to contain plumbing in one area.
-Get a wall chaser with a vacuum outlet. Chasing CEB is very easy and very dusty.

John and Cristobal,  superb info for us all.  A related question please,  about using local soils for this....
My journeys in the Sierra Nevada have been skiing and hiking over hard granite, is that like your area also Cristobal?   Some igneous  I know around hot springs and Mt Shasta region, but trying to see your place in my mind's eye

Rico,

I'm in lower elevation foothills: oak savanna, steep hills, no snow, some granite outcrops.

Rico, I live in an area where naturally occurring mixtures of clay and sand occur widely.
Often just removal with a bobcat, watering and covering the pile to prevent drying out is all that is needed.
Sifting, mixing and adding of any cement or lime is not necessary.
Christos idea of a reo bar bender is clever, I have never used one.

Lime can be used instead of portland cement as a stabiliser.
From memory you use about 5% lime