COMPRESSED EARTH BLOCKS - LIVING BUILDING MATERIAL

Earth blocks are unfired, uniform building blocks, compressed from clay-retaining earth, suitable for use for load-bearing and non-load bearing walls, heat-accumulating walls, heat walls and Finnovens. An earth building forms as it were a third skin around the user and has a warm and restful ambiance.

Health
Earth regulates the climate in the house naturally. The compressed earth blocks are not fired so that the unique moisture-regulating and heat-accumulating properties are preserved. The wall absorbs moisture in wet weather and gives it back when the air is dry.
The bulk of the compressed earth blocks means that an earth wall can storeheat well and give it off again so that temperature fluctuations are fewer.
Earth emits no hazardous gasses or substances into the interior atmosphere and in addition neutralises cigarette smoke for example.

The constant relative humidity of approx. 50% in an earth interior climate prevents fungus forming. That is why an earth house is a "breath of fresh air" especially for people with problems with their airways.

The production process
The compressed earth blocks are produced by a mobile compressing machine, which is capable of producing blocks for larger projects on site as long as the building ground is of good quality. The fertile top soil is temporarily moved aside, the clay-retaining underlayer is dried by the sun and wind and then pulverised. It is then moistened and mixed with sand depending on the proportion of clay in the earth. The compressing machine now makes uniform earth blocks from this mixture which will be ready to be used after a few weeks of drying.

Sustainability and the environment
In many places in the earth (clay, silt, sand) is present in its natural form 20 to 30cm under the fertile top layer and can sometimes be extracted locally. Earth can also be dug out of the building excavations or can be a by-product of road and waterway projects.

The properties of earth do not change during the production of the compressed earth blocks, so that it can be used again without limit as long as earth is used as the mortar and any plastering is done with earth and/or painted with a natural breathing paint. The compressed earth blocks need not be  processed before being returned to the ecological system.

 

 

Energy
Producing compressed earth blocks requires about 1% of the energy needed to produce a building brick. Only 1 litre of diesel is needed to produce 145 earth blocks, making it an energy-saving production process with minimum CO2 emissions.
Less energy will be needed for heating due to the almost constant relative humidity of approx 50% in an earth house in comparison to a more traditionally built house where the relative humidity can reach 80% or more. Energy is saved because a solid earth wall can store heat and solar energy and emit it in the form of radiated heat when the temperature drops.
A large accumulation capacity can be created (if necessary by using the outer gable insulation) with a compressed earth block wall, so that the house is warm in the winter and cool in the summer.

 

 

 

Summary
Compressed earth block (earth, silt, sand), usually present in the natural form.
Earth lime block (earth, silt, sand) with the addition of 5% lime. Water-proof block with very low CO2 load.  About half the CO2 that is released during the production of the lime is eventually re-absorbed by the lime in the compressed earth block.




Shape, dimensions, weight
Shape.  Rectangular (cloister format)
Dimensions. 295mm x 140mm x 90mm.     
Weight: 7.5kg per block. 2200kg per m³.

Appearance
Surface structure. Smooth.
Colour. Red, brown, yellow (depending on the earth type).

Mechanical properties (depending on the earth type)
Compression strength 4-6MPa
Compression strength of earth lime block 6-18MPa
Product strength per suspension point 2 to 5kN, depending on attachment method.

Combustibility
Not inflammable.

Gasses, liquids, solid matters
Diffusion. Diffusion resistance factor: m=<10.
Moisture absorption. Maximum 5 to 7% of the dry weight.
Resistance. Compressed earth blocks are not resistant to running water and rising damp. The compressed earth block stabilised with lime is water-resistant.


Thermal properties
Conductivity. Heat conductivity coefficient: λ=1.13W/(K.m).
Heat resistance. Heat resistance with wall thickness of 40cm: R=0.354w/m².K .
Specific heat. Specific heat: Cw=2000KJ/m³k.
A thermal damping of 10% applies for a 40cm thick solid earth wall with a delay of approx. 10 hours.
Specific heat capacity. C=1.0kJ/kgK.

Acoustic properties
Sound insulation. Sound insulation for a 40cm thick wall is 56dB.

Electricity, magnetism and radiation
Earth cannot be charged with static electricity, neutralises earth and cosmic radiation, mobile and DECT radiation, is not influenced by static magnetic fields and is insensitive to electromagnetic fields.


The Netherlands Institute for Construction Biology and Ecology (NIBE) considers compressed earth blocks to be a good product choice from an environmental and health point of view.

Energy
Energy-saving due to accumulation and moisture-regulation. 30% less energy was achieved in a project in Denmark in combination with solar energy.

Applicability, design
Applicability. New build and renovation. Load-bearing and non load-bearing walls. Accumulating walls. Heat walls. Finnovens.
Design. Bricklaying with earth mortar.

Joint thickness 10-15mm.
½ brick wall 33 blocks/m².
1 brick wall 70 blocks/m².

The blocks must be loaded under pressure because of the physical properties . Pulling and bending forces should be avoided.
Distribute point loads over a large surface area. Permissible compression strength(s) depends on the type of earth.
Protect walls near foundations from rising damp with a water-proof layer.
Water-proof and water-resistant, but damp open, exterior finish. Do not use a vapour retarding layer.

Processing, maintenance
Transport. On Euro pallets (average 120 blocks per pallet).
Storage. Level surface, dry area. Stacked two-high.

 

 

 

Processing
Use earth mortar: dry compressed earth blocks, moistened earth mortar. Always in dry conditions. Laying earth lime blocks: moistened earth lime blocks, moistened earth mortar with lime added. Finishing. Clean brickwork. Finish with earth plaster or another natural breathing material if required.
Processability. Easy to cut, drill and mill.

 

Maintenance
Maintenance. None.
Repairs. Repair mechanical damage with earth

Prices and delivery
On request.

References
Private, social housing and commercial buildings in Denmark, Portugal, Spain, Czech Republic, Macedonia, Sierra Leone, Uganda, Mali, Tanzania. Addresses available on request.


Aesthetic aspects
The cloister format of the blocks, the natural ambiance and the light fall can give a building work additional value.

 

Hjortshøj – Oskam C.E.B.M. Denmark - 1995 Social housing (20 appartments) unstabilised ceb's.

     
Mousing and Skjern-Museum – Oskam C.E.B.M. Denmark'- unstabilised ceb's
     

     

Terracrua Portugal www.terracrua.com

      

 

Habitat Tierra – Spain

  

Schellerpark – Zwolle (The Netherlands)