Design Strategies IMPULSE - Sustainable Facades Vol 2

Figure 1. Criteria of a biodegradable material
Production technique
Raw earth, straw, and water are combined to form
the adobe bricks that make up the structure of the
adobe home. These bricks are then dried in the
sun after being pressed into molds. The Adobe
construction style is ideal for owner-builders since
no expensive tools or equipment are required, and
the skills needed can be quickly gained at a training
session and through hands-on experiences.
Design guidelines
• Orientation and room arrangement: To make
use of the thermal mass of earth walls, adequate
direct sunshine should be allowed to penetrate
an earth structure, especially in winter.
Compressed earth bricks may or may not be
stabilized. However, they are usually stabilized by
cement or lime. As a result, they are now known as
Compressed Stabilized Earth Blocks (CSEB)
Equipment
Today, there are manual presses that are light or
heavy, as well as motorized presses that provide
compression energy via an engine. There are also
mobile machines that combine a crusher and a
mixer in the same equipment. The Impact 2001A
CEB machine from the business AECT Earth block
is seen in Figure 8. This automated machine makes
300 CEBs every hour.
Figure 3. Biodegradable material
• Large eaves are required to protect from
weather damage.
Figure 2. List and category of
discussed materials
• In cold climates, at least the south walls are
insulated. Wool insulation with cladding might
be an excellent alternative since wool is a natural
insulation material with low embodied energy
and hygroscopic properties like earth [8].
Strength:
• In earthquake-prone areas, the structural
design may necessitate vertical and horizontal
reinforcing of earth walls.
• The drying of Unfired earth products requires
less energy input in comparison to fired earth
brick [4].
• Extremely low embodied energy (0.011-0.051
MJ/kg)
• Fire resistance is high (Euroclass fire testing rate
A1-B2)
• Products mixed with straw and other fibrous
materials, usually have lots of thermal mass.
• A CEB wall of 150mm thickness can be resistant
to airborne sound [5].
• Capable to construct self-supporting walls if
their compressive strength is more than 2 MPa.
Weakness:
• Should not be exposed to water for a long
period.
• CEBs may need extra exterior wall insulation for
U-value, despite their high thermal mass in cold
climates [6].
• Stabilizers can affect the final product’s
biodegradability and recyclability, but they are
needed for water resistance and compressive
strength.
• It is advisable to avoid using Adobe Brick for
constructing houses with more than one story [7].
Available products of Unfired Earth are Adobe, CEB,
and 3D-printed walls.
2.1 Adobe bricks
Figure 4. Unfired earth (CEB)
Adobe brick building is an ancient technique
common in the Americas and the Middle East.
In nations with high demand, adobe bricks
are manufactured mechanically at industrial
brickyards, or they can be made on-site by
renting a brick-making machine. According to the
manufacturers, the usual size of an adobe brick
can be 40*20*10 cm
Soil selection
The soil must include between 15% and 30% clay
to provide a suitable binding to the dough. When
using soil with more than 30% clay, adobe brick
will shrink (during sun-drying) and crack, whereas
soil with less than 15% clay will disintegrate.
Furthermore, it is advised that the soil be used
from a depth of 50 cm, eliminating the presence of
organic components such as rotting leaves, plant,
and animal remnants, or roots that may interfere
with the quality of the brick.
• Earth constructions require stable sites. The
site should not flood and, preferably, should not
be exposed to strong rains.
2.2 Compressed Earth Block (CEB)
CEBs began in 19th-century Europe with handmade
blocks. The fi rst steel press in Colombia
improved upon adobe by creating denser, stronger,
and more water-resistant bricks. This technique
has since spread to Africa, South America, India,
and South Asia with the development of advanced
machinery and soil expertise.
Soil selection
Not every soil is ideal for earth construction,
particularly CEB. Topsoil and organic soils are not
permitted. The soil condition and project needs
will influence the choice of a stabilizer. Cement
will be preferred for sandy soils and achieving a
higher strength rapidly. Lime will be utilized for
particularly clayey soil; however, it will take longer
to solidify and provide sturdy blocks.
Production technique
The raw or stabilized soil for a compressed
earth block is slightly moistened before being
poured into a steel press and compacted with
either a manual or automated press. CEB may
be compacted into a variety of forms and sizes.
Figure 5. Typical reinforced adobe wall construction
Figure 6. Adobe Bricks
Figure 7. CEB
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Design Strategies IMPULSE – Sustainable Façades 04.2024 Design Strategies IMPULSE – Sustainable Façades 04.2024
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