Compressed earth block

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A compressed earth block (CEB), also known as a pressed earth block or a compressed soil block, is a building material made primarily from an appropriate mix of fairly dry inorganic subsoil, non-expansive clay, sand, and aggregate. Forming compressed earth blocks requires dampening, mechanically pressing at high pressure, and then drying the resulting material. If the blocks are stabilized with a chemical binder such as Portland cement they are called compressed stabilized earth block (CSEB) or stabilized earth block (SEB). Typically, around 3,000 psi (21 MPa) of pressure is applied in compression, and the original material volume is reduced by about half.

Creating CEBs differs from rammed earth in that the latter uses a larger formwork into which earth is poured and manually tamped down, creating larger forms such as a whole wall or more at one time, rather than building blocks. CEBs differ from mud bricks in that the latter are not compressed, but solidify through chemical changes that take place as they air dry. The compression strength of properly made CEB usually exceeds that of typical mud brick. Building standards have been developed for CEB.

CEBs are assembled onto walls using standard bricklaying and masonry techniques. The mortar may be a simple slurry made of the same soil/clay mix without aggregate, spread or brushed very thinly between the blocks for bonding, or cement mortar may also be used for high strength, or when construction during freeze-thaw cycles causes stability issues. Hydraform blocks are shaped to be interlocking.