“The following study was done to test the feasibility of interlocking soil/cement compressed blocks in residential construction in North America. The study collected data on compressive strength of the blocks as well as observations on how they can be used.
Soil/cement Block (also known as Compressed Earth Blocks or CEBs):
A soil/cement block is a compressed block made from a mixture of subsoil, cement, and water. Many different types of earth blocks have been used throughout the world for centuries. The soil/cement earth block has several advantages over traditional earth blocks.
Traditional earth blocks can be made from clay, mud, and farm residue (straw, rice husks, hemp, etc). Many of these blocks can be swept away by heavy rains or flood. The soil/cement earth blocks have a small percentage of cement mixed in with the subsoil to stabilize it. The sand and silt in the soil reacts with the cement when it is mixed and compressed. After the block is compressed, it requires only air and water curing.
Soil/Cement Blocks also offer advantages in construction time due to the block having a male and female interlocking system. The blocks interlock without the use of mortar in between each layer (The exception is the first layer which has to be mortared and leveled on the foundation footers). The simplicity of the system also allows untrained labor to be used, reducing construction costs. The shape of the block also has hollow openings that allow the use of steel reinforcement and the placement of grout.
There are many different types of machines and presses that can be used to make these blocks. Some presses require the use of human power and others involve electrical hydraulic compression. For this study, a hydraulic press was used. This allowed one person to operate the machine. Consistent compression could also be achieved because of the electrical motor. The machine was made by Shandong Shengya Machinery Company in China. The machine used about 2.2 kw of electricity during production. On assembly line production this press can do about 2.5 blocks per minute on average. I am sure with trained labor a press operator can exceed 3 blocks per minute.
Economics of block production:
The machine that we used can produce about 1200 blocks in an 8 hour shift. The block measured 150x300x100cm. Since the study’s goal was not originally designed to provide economic figures, I only made rough estimates during the study. If 3 laborers were hired at 12 dollars an hour, the labor cost per block would be less than .25 cents per block. Subsoil and cement rates can vary throughout the country. The ranges can go from 12- 35 dollars a ton for soil depending on the delivery charge. Even with these price ranges, a block can still be produced for under .55 cents including labor.”
The full report will hopefully be available soon.
You can reach Naveed at naveed3485 [AT] yahoo.com
Owen: Are you getting stronger, more uniform results with a hydraulic press?
Naveed: We noticed during the manual press there is inconsistency but because of the new hydraulic machines they are less prone to this. There is a company called roadpackers international that is selling a clay stabilization liquid that allows the block to be stabilized without cement or extremely small amounts. I will try to do some tests with this as well because cost will be even cheaper. Usually the high clay content would mean you have to add sand and more cement but Roadpackers liquid stabilizer works best with high clay soils and does not need the added cement or sand. My friends in Missouri are set to build Aug. 13. I will have pictures for you when everything is complete.
16 thoughts on “Report on Compressed Earth Blocks”
Great info, thanks to all
Hello from southern mexico,
I recently acquired an Earth Blox ceb machine. The blocks turn out beautiful, but they arent as strong as I had hoped. I’m feeling like the curing process is the problem.
Any tips on proper curing? We’re adding 6 to 8% portland cement to the mixture.
Thanks for your comments.
Two ideas: Did you add fiber such as straw? Also, research the proper drying process of adobe bricks (sun dried mud bricks). You want to dry your bricks/blocks gradually from the inside out while stored in the shade. Rapid drying in the sun for example creates weaker bricks. Also, use clean water and ‘strong soil’ (weak soil is a common problem because it lacks bonding strength).
Thanks for your comments! So quick…
Im trying to avoid using straw and other organics, since this is a mechanized hydraulic press (made by Vermeer). I’m thinking that the drying process is where our problem is. I also think i may have to add some soil with more clay in it to the mixture.
I’m still in the experimenting & learning stage, so any advise or suggestions are welcomed.
Thanks again for your help!
Read up on cohesive/strong soils and keep doing tests. There’s a big difference in soil types. Engineers prefer special mixes such as road base. This is the material used under roads.
Soil cement blocks have to be moist to somewhat wet for around 30 days while the hydration process occours otherwise you will end up with weak cracking block..the curing process for seb should be as follows..after pressing the stabilized earth let them cure under a damp burlap tarp or equivalent for 10 to 20 hours and then soak the stack twice a day to avoid premature drying for a week..after a week wet them once a day for the rest of the month and then let them dry before use..I use,15 to 20% portland cement in my mix along with a polymer ad mixture for added tensile strength on beams..this method has greatly improved the quality of block I can produce
At our office, we design and build residential and commercial buildings with Compressed Earth Blocks in the Central Texas region with time-tested techniques that meet code and performance requirements.
Our partners provide the machinery and specialized construction teams for this underutilized and exceptional building technique.
CEBs outperform adobe and concrete masonry at a price nearly matching wood framing, with easily available material and a ridiculously high on-site production rate.
Feel free to contact us at Frontier Architects for design and collaboration opportunities.
CEBs are one of my favorite building methods for all the reasons that you mention. That’s why we do regular blog posts about this type of construction. In some areas of the world there are hundreds of thousands of CEB buildings. And note the recent development of geopolymer blocks by Watershed Materials that are made with natural clay and minerals. They meet code and are twice as strong as cement blocks.
The adobe code developed in New Mexico is accepted in many locations. We are using that code in Florida, until I can get the Florida Building Commission to accept SCEB’s in their own right.
I have an automatic interlocking compressed earth block machine and have done testing with enzymes. They have failed miserably when used alone. However, when added to the soil/cement mixture just prior to compression, it adds to the stabilization.
Can I build up to two levels with these blocks?, if yes, what is the best pattern bond I can use
Yes, this is very common. The standard pattern is a regular running bond. Also many builders create different size columns. They can be integrated into the wall or build separately.
How about geopolymer stabilization? Is there a cheap, available geopolymer “recipe”?
That’s possible, although it’s time consuming to figure it all out. My Geopolymer House blog has lots of info on geopolymer, including recipes. Use the built in search engine using keywords recipe or formula.
I like this approach to construction blocks, both their inter-locking feature and their composition. Concrete is no longer inexpensive and a reasonable substitute is needed to hold down building costs. Will it ever be able to clear the hurdles of building regulations in America? I hope it does.
I think this type could get permitted in the US. Check out the New Mexico earth building code and contact earth building architects in the area.