Compressed Stabilized Earth Blocks (CSEB):
Compressed Stabilized Earth Blocks (CSEB), commonly called, Pressed Earth Blocks, are construction material made using damp soil under high amounts of pressure to form blocks. They are composed of dry inorganic subsoil, non-expansive clay, aggregates and Portland cement. CSEBs are an environmentally friendly alternative to clay bricks that most of the residential construction in India today uses.
The first attempts for compressed earth blocks were tried in the early days of the 19th century in Europe. The architect François Cointereaux precast small blocks of rammed earth and he used hand rammers to compress the humid soil into a small wooden mould held with the feet.
The soil, raw or stabilized, for a compressed earth block is slightly moistened, poured into a steel press (with or without stabiliser) and then compressed either with a manual or motorized press. CEB can be compressed in many different shapes and sizes. For example, the Auram press 3000 proposes 18 types of moulds for producing about 70 different blocks.
These compressed earth blocks can be stabilised if needed and are stabilised with cement or lime thus giving them the name compressed stabilised earth blocks (CSEB). This input of soil stabilization allowed people to build higher with thinner walls, which have a much better compressive strength and water resistance. With cement stabilization, the blocks must be cured for four weeks after manufacturing. After this, they can dry freely and be used like common bricks with a soil cement stabilized mortar.
However Not every soil is suitable for earth construction and CSEB in particular. But with some knowledge and experience many soils can be used for producing CSEB. Topsoil and organic soils must not be used. Identifying the properties of a soil is essential to perform, at the end, good quality products. Some simple sensitive analysis can be performed after a short training. Cement stabilisation will be better for sandy soils. Lime stabilisation will be better suited for clayey soils. The selection of a stabilizer will depend upon the soil quality and the project requirements. While cement is preferable for sandy soils and to achieve quickly a higher strength, lime is used for very clayey soil, but takes longer time to harden and to give strong blocks. The following are the types of blocks
Plain square blocks
This block is used for building plain load bearing walls of 24 cm thick. It can be used up to 4 floors high. It presents the advantage of saving mortar and allowing a fast block laying.
Plain rectangular blocks
This block is used as a single block width for light load bearing structures, or as a double block width for heavy load bearing structures.
It presents the advantage of saving mortar and allowing a fast block laying.
This block is used for building composite columns (Reinforced cement concrete in the middle hole).