Approdocs Collection

From: Compressed Earth Blocks & Soil Moisture: A Useful Document describing preparation of mixes with various soil types (high clay / low clay content)

" When pressure is applied to soil, you are locking the larger particles together, but they won't stay locked without a binder -clay/silt are binders. This is why compression machines need more clay than traditional
sun dried Adobe and the soil is worked much drier. "

From: Ferncometal.com Library

" Q: Will using your block presses guarantee that my blocks will pass state or county structural integrity tests?

A: No! It’s neither the machine nor the amount of pressure applied that makes a strong block; it’s the recipe of your soil mix that determines the strength of your blocks.

Fernco produces the MP-612, a portable, manually-operated press that produces a 6" x 12" x 3-1/2" compressed earth block "

From: Compressed Earth Bricks The LCH Stabilised Earth Brick (SEB) Machine and related projects described:

A soil that contains 15%> percentage of clay, must be used, pure sand will not work. If inferior soil or clay is to be used, then a clayey material will have to be imported and properly mixed with the in-situ material

Mix the soil with the prescribed dosage of RoadPacker Clay Brick Stabiliser per m3 of material/soil.

>>> >> I'm not sure what 'RoadPacker ..' is, but most recipes have 4-10% portland cement in the mix. - ed. GW

From: Compressed Earth Block wikipedia page.

Code work was completed June 10, 2002 and melded into New Mexico's new section, R1100 Earthen Building Materials.

The CEB code is different from the adobe code in numerous respects. For instance, the CEB code allows slip mortars and permits blocks ejected from a press to go directly to the wall.

CEB Strength: Using the ASTM D1633-00 stabilization standard, a pressed and cured block must be submerged in water for four hours. It is then pulled from the water and immediately subjected to a compression test. The blocks must score at least a 300 pound-force per square inch (p.s.i) (2 MPa) minimum. This is a higher standard than for adobe, which must score an average of at least 300 p.s.i. (2 MPa)

It must be emphasized that the compressive strength minimums for code compliance are nothing like the true strength of CEB blocks. New Mexico only sought to assure that CEB would be at least as strong as adobe.

CEB can have a compressive strength as high as 2,000 pounds per square inch (13.7×106 Pa). Blocks with compressive strengths of 1,200 (8.27×106 Pa) to 1,400 p.s.i. (9.65×106 Pa) are common.

Rammed Earth building techniques should be reviewed as well due to the similarity in materials and production to Compressed Earth Bricks. ref: Rammed Earth Wikipedia Page

Rammed earth trombe wall built by the University of Utah's Design Build Bluff project

Because rammed earth structures use locally available materials, they typically have low embodied energy and generate very little waste. The soils used are typically subsoils low in clay, between 5% and 15% typically with the topsoil retained for agricultural use.

Manufacture of the cement adds to the global carbon dioxide burden at a rate of 1.25 tonnes per tonne of cement produced[8].