Compressed Earth Blocks
From Swikipedia
Introduction
Compressed Earth Blocks, or CEBs, are construction blocks made with clay, sand, and a stabilizing ingredient such as lime or Portland cement. The earth mixture is poured into a hand-operated or motorized hydraulic press machine. Since they are machine-made, compressed earth blocks are uniform in size and shape.
The concept is not new and has been in existence for ages. Today CEB is the new ‘green’ way of building.
Brief Description
What are CEBs made up of?
CEBs are made of soil whose ideal composition is: 15% gravel, 50% sand, 15% silt, and 20% clay. The moisture content in the CEB should be 3-8%. Moisture levels lower will result in falling apart of the block and higher levels will result in a weak block. Sand is necessary to increase comprehensive strength. Straw is not required as it is mainly added to adobe for moisture reduction and since CEBs hold low moisture, adding straw will result in cracking.
Advantages:
Uniform building component sizes: Uniformly sized building components can result in less waste, faster construction and the possibility of using other pre-made components or modular manufactured building elements. Such modular elements as sheet metal roofing can be easily integrated into a CEB structure. The possibility of using such components can often improve the overall quality of the structure as well.
Use of locally-available materials: The use of natural, locally-available materials makes good housing available to more people, and keeps money in the local economy rather than spending it to import materials, fuel and replacement parts. The earth used is generally subsoil, leaving topsoil for agriculture. Building with local materials can employ local people, and is more sustainable in times of civil unrest or economic difficulties. People can often continue to build good shelters for themselves regardless of the political situation of the country.
Reduction of transportation: The reduction of transportation time, cost and attendant pollution can also make CEB more environmentally friendly than other materials. Most of the time, soil for CEB can be found on site or within a short distance. In most of the world's economies, the most cost-effective transportation is often that provided by people or animals.
Cost Effective & Environment Friendly: Compressed earth blocks are a more cost effective and environment friendly option for construction, due to use of locally available materials and non-renewable sources. It is highly affordable, especially in poor countries and cheap to transport.
Energy efficient and fire & mold resistant
Disadvantages:
Building officials usually fight it, as they do not know how to use it.
Limited use in developed countries
Slower to build with when compared to wood construction
Some architects don’t believe in the product
References:
http://www.networkearth.org/naturalbuilding/ceb.html
http://architecture.about.com/od/greenarchitecture/g/earthblock.htm
http://www.daenvis.org/daesat/compressed.htm
http://www.ewb-international.org/pdf/presentation-3-23-09.pdf
