$300 Geopolymer CEB House
Compressed earth blocks (CEBs) are typically made with soil and cement. I propose making CEBs out of geopolymer, as pioneered by Professor Joseph Davidovits. The resulting blocks would be actual stone and so the finished homes would be extraordinary.


Compressed earth blocks (CEBs) are widely popular around the world due to their low cost and suitability for do-it-yourself manufacturing and construction, particularly in developing countries where labor is cheap. Typical CEBs are made of soil mixed with about 10% cement and then compressed in a machine-driven or hand operated press.

This video shows the basic block making process:
Making Compressed Earth Blocks

The primary innovation for this design competition uses geopolymer to make CEBs. Geopolymer was rediscovered by Professor Joseph Davidovits and other researchers at the Geopolymer Institute.  The basic process involves combining loose limestone, kaolin clay, sodium carbonate, lime and water � all low cost, commonly available materials. The binders (sodium carbonate and lime) can be purchased off the shelf. Scientists also have shown how all the necessary materials can be obtained from fly ash, slag from iron ore processing, and mining tailings to produce geopolymer cement from 100% waste materials. Note: geopolymer can be used with other types of soil and minerals besides limestone. Laterite soil for example, which is very common in the southern hemisphere, is another possibility.

Here�s an excellent video that shows how to make geopolymer blocks. Just imagine taking this same mix and compressing it in a CEB press to make blocks.
How the Pyramids Were Built

Advantages of CEBs:
- proven technology used in dozens of countries for decades
- CEBs are already popular, which means there would be little to no resistance to adoption of this technology
- fire, flood, seismic and wind resistant, and not susceptible to insect damage
- CEB equipment is affordable even in developing countries (example: a housing group can purchase the equipment, build hundreds of houses and then continue making and selling blocks for many years)
- low cost building materials (many shapes and sizes of blocks are possible)
- creates cottage based industries that keeps money in the community
- uses all natural, environmentally friendly materials
- easy to learn skills (somewhat like putting together Legos)
- enables homes to be built gradually as time and resources allow
- CEB presses last decades with very little maintenance

Advantages of interlocking hollow core CEBs:
- blocks readily align due to matching male/female parts
- provides spaces for rebar and grout reinforcing so houses can meet safety requirements for hurricane regions, seismic zones, etc.
- no mortar required between courses
- lighter weight, uses fewer resources, faster drying

Advantages of geopolymer:
- blocks would turn to actual stone, which means they would be even stronger, more fire resistant, waterproof, etc.
- geopolymer walls 'breath' or allow moisture to pass through, thus providing excellent indoor comfort and humidity control
- mix design can be adjusted to utilize many types of soils and minerals

The proposed house design would be very similar to my $300 Earthbag House � What the World Needs Now.  It would be easy to rework the drawings and replace the earthbags with CEBs.

This blog post provides pricing information and more details on CEB block making equipment.