Download Earth-a new look for an old material

EARTH-A NEW LOOK FOR AN OLD MATERIAL
2011
VLAD BURLACU
2 Earth-a new look at an old material
Abstract:
The development of earth as a building material is linked to previous structures
constructed centuries ago with rudimentary methods. The methods of building with earth
are developing each year in parallel with people concerns about environment issue. Earth
as a building material plays a major role in our surrounding environment, but people
preconceptions distort it after World War 2. In our days some people still trying to go
back living in harmony with nature and environment, making researches to improve the
quality of this ancient building material, educating people and guide them towards a
higher living standard. Improving the thermal mass, strength of the material and
minimize the maintenance of earth structures will increase also the confidence and
acceptance of this old material. In this way maybe the negative rumors will be gone and
people aim for a sustainable material.
3 Earth-a new look at an old material
Acknowledgements:
This report couldn’t be written without the help and guidance of Heidi Sørensen Merrild
On this path I would like to say thank you very much for her support. Also I would like to
thank also to my family to be nearby me when I was very stress, encouraging me all
time.
4 Earth-a new look at an old material
Table of Contents
Introduction: ..........................................................................................................5
Problem statement: ................................................................................................6
History of building with earth: ..................................................................................7
Methods used building with earth: .......................................................................... 11
Adobe: .............................................................................................................. 11
Cob: ................................................................................................................. 12
Compressed earth bricks: .................................................................................... 13
Rammed Earth:.................................................................................................. 14
Earth bags: ....................................................................................................... 15
Why building with earth is not so popular: ............................................................... 16
Structural Design: .............................................................................................. 17
Energy efficiency:............................................................................................... 19
Measures to improve the characteristics of earth: ..................................................... 23
Shrinkage: ........................................................................................................ 23
Water erosion: ................................................................................................... 24
Improving thermal insulation: ................................................................................ 29
Insulating render: .............................................................................................. 29
Hemp lime......................................................................................................... 29
Cork insulation ................................................................................................... 30
Cellulose insulation ............................................................................................. 30
Sawdust, wood shavings and chips ....................................................................... 31
Conclusion: .......................................................................................................... 32
List of figures ....................................................................................................... 33
Reference list ....................................................................................................... 35
5 Earth-a new look at an old material
Introduction:
Since the industrial revolution, fossil fuels have made possible most of the
construction in developed countries, meaning that they have been able to overcome the
limitations of human labor. This has been at enormous cost in terms of pollution and
carbon emissions, massive overconsumption of resources and an increase in
unemployment.
People in industrialized countries are rapidly realizing that the days of cheap energy and
gross wastefulness are numbered. The quest for low cost, healthy, non-polluting, low
energy building materials and techniques is gaining momentum, and earth is being
rediscovered as being superior to so-called modern materials such as concrete, glass and
steel.
Today, with the high and increasing cost of modern construction materials, most people
in developing countries cannot afford to use them. Therefore the use of earth, the most
ancient and ubiquitous of building materials and a do-it-yourself approach.
Earth- is an ancient building material that is still used in many different ways with
about half the world’s population still living in earth buildings. In architecture, material of
earth, this plays an important role and is the basis for any type of construction. The earth
as a material very closely linked to environmental and aesthetic self-esteem. In short,
earthen architecture is the use of land, an abundant natural material for the design and
construction of buildings.
6 Earth-a new look at an old material
Problem statement:
This report has been written as a compulsory assignment in the seven semester
Constructing Architect degree course. I began my report by reading two books from the
library about this interesting subject, “Building with Earth Design and Technology of a
Sustainable Architecture” by Gernot Minke and “Earth Architecture” by Roland Rael. Also
a huge amount of information I found very interesting on internet, differend websites and
organizations who are trying to promote this material as a sustainable construction
method. Finding this amount of information, documents and researches made up until
now I choose the following research questions:
 Why building with earth is not so popular from the structural design and energy
efficiency point of view?
 What measures are to improve the characteristics of earth as a building material?
 How to improve thermal insulation of earth buildings?
7 Earth-a new look at an old material
History of building with earth:
Earth construction techniques have been known for over 9000 years. It has been
used as a building material in all ancient cultures, not only for residential houses but for
religious buildings as well. As a representative from the African continent, is the religious
building discovered, the Temple of Ramses II at Abu Simbel, Egypt build 3200 years ago,
using mud bricks.
Figure 1. Temple of Ramses II at Abu Simbel, Egypt
Another discover which was made is a fortified city in the Draa valley in Marocco, which is
250 years old, build with local red clay.
Figure 2. Draa Valley-Marocco
Many large building earthworks around the world have withstood the test of time, the
representation of the great advantages of using the soil for construction and architectural
process. One such example is from Asia; the 4000-year-old Great Wall of China, was
8 Earth-a new look at an old material
originally built of rammed earth, only a later covering of stone and bricks gave it the
appearance of a stone wall.
Figure 3. Great Wall of China
In Middle East the biggest adobe building in the world is Citadel of Bam from Iran, over
2000 years old. The earthquake from December 2003 destroyed around 80 % of the city.
Figure 4. Citadel of Bam- Iran
Also still standing, with an impressive height of 38 meter, is Al Midhar Mosque
constructed with adobe and 1000 year-old earth built skyscrapers in Shibam, Yemen.
Figure 5.a) Al Midhar Mosque,
Yemen
Figure 5.b) Shibam, Yemen
9 Earth-a new look at an old material
The Romans used rammed earth to build throughout Europe - Italy, Spain,
Portugal, Germany, France and England.
In the medieval period, earth was used throughout Central Europe as infill in timberframed buildings, as well as to cover straw roofs to make them fire-resistant.
In Europe the oldest example of mud brick walls was discovered in Heuneburg Fort,
Germany- 6th century BC. Earth building in France and Germany has a long tradition. In
the 18th century the construction of earthen architecture was very widespread through
the published work of Francois Cointeraux and David Gilly, which had a big influence on
the development of earth building. The oldest framework house with earthen interior in
the region of Berlin-Brandenburg, built in 1408 in the Brandenburger Bäckerstraße.
The oldest still existing rammed earth building was built 1795 in Meldorf, SchleswigHolstein. The owner wanted to show that rammed earth as a construction method is
much more fire resistant than traditionally built framework houses. The aspect of fire
resistance was one reason for the introduction of earthen architecture in the 18th century
in Germany. The highest rammed earth building of middle Europe is found in Weilburg,
Germany constructed in 1828. This rammed earth building has 5 floors and symbolizes
not only the durability of earthen architecture but also documents the possibility of
constructing higher than 2 floors when operated with the rammed earth building
technique.
Figure 6.Weilburg, Germany
10 Earth-a new look at an old material
In France, the rammed earth technique, called terre pisé, was widespread from the 15th
to the 19th centuries. Near the city of Lyon, there are several buildings that are more
than 300 years old and are still inhabited. In the Rhone River valley of France rammed
earth was the dominant form of construction for centuries with over 250,000 buildings
still in use. In France, about 15% of the populations are living in earth walled houses.
Figure 7.France, Reyrieux-Castle XVIII century
In North America between 1780 and 1850 thousands of earth buildings were made. With
the arrival of mass-produced brick and lumber and the popular perception that new is
better, rammed earth construction faded until its resurgence after World War 1, and
lasted until the early 1950’s. The industrial revolution’s influence in the construction
industry saw a decline in rammed earth building. Within a couple of generations the art of
building rammed earth had faded and was virtually unheard of; thankfully it has been
maintained in many parts of the world to keep this exceptional construction technique
alive. The tests that the US government in the 1930’s and the literature from that have
contributed to the revival of rammed earth. Today in both Canada and the US the
popularity of rammed earth is increasing due to environmental, economic and social
concerns.
Also the great architect Frank Lloyd Wright designed homes of rammed earth and wanted
to use this type of construction in his proposed Broad acre City project but his generation
wasn't ready for this kind of material.
Figure 8. Frank Lloyd Wright rammed earth house
11 Earth-a new look at an old material
But earth building is not used only in the Third World or the developing countries - in
some regions of Australia over 20% of the houses are built with walls of unfired earth.
Methods used building with earth:
Adobe:
Adobe is one of the oldest building materials in use. It is basically just soil that has been
moistened with water, sometimes with chopped straw or other fibers added for strength,
and then allowed to dry in the desired shape. Commonly adobe is shaped into uniform
blocks that can be stacked like bricks to form walls. The best adobe soil will have between
15% and 30% clay in it to bind the material together, with the rest being mostly sand or
larger aggregate. Too much clay will shrink and crack excessively; too little will allow
fragmentation. Sometimes adobe is stabilized with a small amount of cement or asphalt
emulsion added to keep it intact where it will be subject to excessive weather. Adobe
blocks can be formed either by pouring it into molds and allowing it to dry, or it can
pressed into blocks with a hydraulic or leverage press. Adobe can also be used for floors
that have resilience and beauty, colored with a thin slip of clay and polished with natural
oil.
Adobe buildings that have substantial eaves to protect the walls and foundations to keep
the adobe off the ground will require less maintenance than if the walls are left
unprotected. Some adobe buildings have been plastered with Portland cement on the
outside in an attempt to protect the adobe, but this practice has led to failures when
moisture finds a way through a crack in the cement and then can't readily evaporate.
When adobe is used as an exterior plaster it is either stabilized or replastered on a
regular basis.
Adobe is a good thermal mass material, holding heat and cool well, but they are known to
be particularly susceptible to earthquake damage. It does not insulate very well, so walls
made of adobe need some means of providing insulation to maintain comfort in the
building. Sometimes this is accomplished by creating a double wall, with an air space, or
some other insulation in between. Another approach is placing insulating materials on the
outside.
Figure 9. Romania, Danube Delta-Making adobe bricks
12 Earth-a new look at an old material
Cob:
Cob is a building material consisting of clay, sand, straw, water, and earth, similar to
adobe. These ingredients can be mixed together by hand, using tarps, or by machinery.
The mix is formed into cobs which are pressed together to form the walls of a building.
The walls of a cob house were generally about 60 centimeters thick, and windows were
correspondingly deep-set, giving the homes a characteristic internal appearance. The
thick walls provided excellent thermal mass which was easy to keep warm in winter and
cool in summer. Walls with a high thermal mass value act as a thermal buffer inside the
home. The material has a long life span even in rainy climates, provided a tall foundation
and large roof overhang are present.
Cob is fireproof, resistant to seismic activity, and inexpensive. It can be used to create
artistic, sculptural forms and has been revived in recent years by the natural building and
sustainability movements. A cob house can vary in freedom of design and shape.
The major difference between cob and adobe is that the cob has more straw mixed into it
than the adobe does. Another difference is that it tends to be less expensive, as it is not
as trendy in popularity as adobe so costs have not been driven up.
Figure 10.a) Group of people mixing cob with feet
Figure10. b) Cob house-freedom of design
13 Earth-a new look at an old material
Compressed earth bricks:
Compressed earth bricks (CBE) are building blocks formed from stabilized or un-stabilized
compressed earth. The compression ranges from several hundred kilos total, to several
tons. Because of the great gains in durability un-stabilized bricks are only used where
nothing is available to stabilize the bricks. In addition to stabilization, the earth the bricks
are to be made from is calibrated for durability, workability, and survivability.
When a brick is compressed it loses 30% of its volume. This is due to the mechanical
compression of the press driving out air pockets and aligning wet clay particles and
compacting the clay around the sand particles.
The compression can be made with hand-operated presses, which have been used for
many decades, and still today, some people make the blocks by beating soil into a
wooden mold with a stick.
Also modern equipment, with hydraulics driven by diesel, gas or electric motors, may be
used in urban areas or for large multi-house sites.
"Rammed earth" is a similar process, in which case a structure is made as one continuous
mass of compressed earth.
Figure 11. a) Hydraulic press
Figure 11. b) Hand operated press
14 Earth-a new look at an old material
Rammed Earth:
A temporary frame is first built, usually out of wood or plywood, to act as a mold for the
desired shape and dimensions of each wall section. The frames must be sturdy and well
braced, and the two opposing wall faces clamped together, to prevent bulging or
deformation from the high compression forces involved.
Rammed earth is a method of building walls whereby a mixture of earth is compacted in
layers between forms. Each layer of earth is approximately 15-25 cm deep. As each form
is filled, another form is placed above it, and the process begins again. This is continued
until the desired wall height is achieved. Forms can be stripped off as soon as the form
above is begun, as the compressed earth wall is self-supporting immediately. Most
rammed earth builders use pneumatic rammers to compact the earth within the forms or
hand operating ramming pole.
The soil mix needs to be carefully balanced between clay, sand and aggregate. The clay
and moisture content of rammed earth is relatively low compared to that used for mud
brick or other earth building methods.
A wider range of soils are suitable when a small amount of cement is added to the mix.
The result, known as ‘stabilized rammed earth’, is a strong masonry product which
provides excellent thermal mass.
Walls take some time to dry out completely, and may take up to two years to completely
cure. Compression strength increases with increased curing time, and exposed walls
should be sealed to prevent water damage.
Figure 12. a) Step by step rammed earth wall
Figure 12. b) Hand operating ramming pole
15 Earth-a new look at an old material
Earth bags:
Using soil-filled sacks (earth bags) for construction has been recently revived as an
important natural building technique. Most commonly the bags used are made of
polypropylene or burlap.
If we look back to the history we can observe the military use sandbags to create such
barriers, which would stand up against the weather and the threat of force by oncoming
armies. Also in the earlier days they were used in case of floods.
Everything from volcanic rock to adobe soil can be used to fill the bags and create
natural, earth-based building blocks, usually available on site. The fill material can be
used either wet or dry, but moistened material creates a more stable structure. An
efficient system is to create your sack foundation and/or walls using soil from site
excavation.
To improve rigidity between each row of bags barbed wire is often placed between the
courses. Twine is also sometimes wrapped around the bags to tie one course to the next,
serving to hold the in-progress structure together and add strength. The structure is
typically finished with plaster, stucco or adobe both to shed water and to prevent any
degradation from solar radiation. This construction technique can be used for emergency
shelters, temporary or permanent housing, barns or most conceivable small-to-mediumsized structures.
The walls can be curved to provide improved lateral stability, forming round rooms and
domed ceilings like an igloo or domes. Buildings with straight walls longer than 5 m in
length need either intersecting walls or bracing buttresses added. International standards
exist for bracing wall size and spacing for earth construction in different types of seismic
risk areas.
Figure 13. a) Earth bags with barbed wire
Figure 13. b) Ghana, Ashanti Region art villagepersonal project
16 Earth-a new look at an old material
Why building with earth is not so popular:
"Facts do not cease to exist because they are ignored." — Aldous Huxley
Earth has proven to be one of the world's best building materials because it is historically
the longest used by man, nature's product, universally available, a heavy solar mass, a
natural barrier to cold winds and forces of nature (Including tornadoes, earthquakes, and
hurricanes.), insects and rodents, not rationed, not monopolized by anyone, a superior
building material, fire proof, and sound proof. Earth has been a basic building material
since the dawn of man. Architecture in earth, whether it is relatively unknown, scorned,
or praised and admired, continues to live on.
But the ignorance and prejudice against earth is still widespread. Many people cannot
conceive the notion that as natural building materials, such as earth is necessary. A lot of
money, time, and research have been invested in earth construction. During the latter
1920's until the late 1940's.Millions of governments monies were spent on the research of
earth construction. The U.S.A, the United Nations, the governments of England,
Germany, France, Israel, Australia, New Zealand, Belgium, Poland and Russia have all
conducted studies which found earth to be a good building material and recommend its
use for housing.
The results of that test were positive. The reports noted that earth structures, which
would last indefinitely, could be built for as little as two-thirds the cost of standard frame
houses. The earthen homes were shown to be considerably less expensive to heat and
cool. This information has generally been ignored.
Interest for earth to be used as a construction material goes down after World War II,
when building materials became abundant and very cheap. Earth is viewed as
substandard and in fact suffers a prejudice. People couldn't accept to live in a "dirt house"
as in medieval times. It may have been the construction industry, which depends so
heavily on material-intensive methods that helped deprive earth of its rightful position in
building. Furthermore, the public's then increasing want for miracle synthetics certainly
had something to do with the lack of acceptance of earth technique.
Acceptance of earth is not simple and is not easy. The lack of knowledge of earth building
techniques is exceeded only by the opposition of some who do know a little about it.
Earth builders have faced the unspoken skepticism and open criticism of engineers,
builders, government officials and the public.
Introducing soil as a "new" building material on the market will meet the cons of the
engineers, contractors and architects which will reject the material first of all because
they are not familiar with this old "unconventional" material. They are also the first
people in the construction industry who can take grand's for this. But with workshops and
education the people can be guide it towards the earth, as a building material.
17 Earth-a new look at an old material
If we are comparing earth with standard building materials we can find some
disadvantages which are:


Earth is not a standardized building material depending on the site where the earth
is dug out, it will be composed of differing amounts and types of clay, silt, sand and
aggregates. This characteristic may differ from site to site.
Earth mixtures shrink when is dry
Due to evaporation of the water used to prepare the mixture (moisture is required to
activate its binding strength and to achieve workability), shrinkage cracks will occur. The
linear shrinkage ratio is usually between 3% and 12% with wet mixtures (such as those
used for mortar and mud bricks), and between 0.4% and 2% with drier mixtures.
Shrinkage can be minimized by reducing the clay and the water content, by optimizing
the grain size distribution, and by using additives.

Earth is not water-resistant
Earth must be sheltered against rain and frost, especially in its wet state. Earth walls
can be protected by roof overhangs, damp-proof courses, and appropriate surface
coatings.
In recent years, sustainable construction projects have increased all over the world but in
many countries, not only the developing countries, have difficulties in obtaining finance or
insurance for projects involving the use of not a standardized building material or
systems. This is another reason why, again many people avoid living in earth sheltering.
The use of earth as a building material is more used in the developing countries because
is an affordable material which in many countries is still a resource. Cheap and
sustainable earth is getting a good reputation each year also in western countries first of
all because people concerns about the environment.
In the last chapter we talk about the cons against earth as a building material, let’s
continue with the advantages and pro opinions.
Structural Design:
Load bearing earth buildings have developed over years in the absence of structural
design standards or codes. For geometric wall proportions developed through the
experience of trial and error have proven sufficient to enable earth building to achieve at
least 10 stories high. The majority of earthen buildings are low rise, single or two storey,
and consequently the stresses experienced by the thick earth walls are generally well
within the modest capabilities of the material.
In Germany DIN 18954 Standards relating to earth building were developed following
World War II, though were subsequently withdrawn in 1970. In Australia the first edition
of Bulletin 5, a national reference document for earth building, was published by CSIRO in
1952 (Middleton, 1992).
After Bam Citadel, from Iran was hit by 6,6 earthquake in 2003, destroying almost 70
percent of the city, international awareness increased. Despite of that earth architecture
didn’t have a bad reputation being dangerous. Many researches are continuing at
18 Earth-a new look at an old material
Pontificia Universidad Catolica del Peru, University of Kassel from Germany and
University of Technology from Sydney, Australia and they achieve the milestone to build
earthquake resistant earth structure.
In case of seismic activity forces are transmitted in the corner of the building or the
openings producing cracks and failure of the building.
When we are talking about structural design against earthquakes, some of the facts
should be avoided as it follows:
 trying to avoid the sloppy sites
 the plan of the earth building should be compact and symmetrical
 the segments of the building should have the same foundation level
 foundation should be reinforced
 building elements should be well fixed with each other, the joints being able to
resist the shear forces produced by the quake
 load-bearing masonry walls should have minimum thicknesses of 30 cm
 building corners, joints between and door openings have to be stiffened by vertical
posts of by timber or reinforced concrete, which are structurally fixed in the
foundation
 walls have to be finished on top by a ring beam and also trying to avoid extra lintels
above windows and doors
 roofs should be constructed as light as possible
 openings in the load bearing walls should be proportioned
According to Gernot Minke in his book “Building with earth”, binding force (tensile
resistance of loam in a plastic state) depends not only on clay content, but also on the
type of clay minerals present. As it is also dependent on the water content, the binding
force of different loams can only be compared if either water content or plasticity is equal.
Also the author run a compressive strength tests of dry earth elements and give to
examples: earth block and rammed earth wall which differ in general from 5 to 50
kg/cm. Again this depends not only on the quantity and type of clay, but also on the
grain size distribution of silt, sand as well as on the method of preparation and
compaction.
Earth used in building has good strength in compression, but less strength in tension.
When earth is used as a load bearing material, forces must pass down within the
thickness of the structure to the ground, down to foundation. For this reason monolithic
load bearing walls tend to be thick. However, it is possible to construct slender walls,
arches and vaults in earth if care is taken to support these structures while they are
drying out. Minimum recommended thicknesses earth walls vary depending according
with building design codes, country, climate and seismic activity.
Figure 14.Minimum thickness of wall
19 Earth-a new look at an old material
Energy efficiency:
People usually spend about 90% of their time in enclosed spaces, so indoor climate is a
crucial factor in well-being.
Increasingly, people when building homes demand energy- and cost-effective buildings
that emphasize a healthy, balanced indoor climate.
Earth has an excellent thermal mass which can give a comfortable interior temperature
without using mechanical cooling or heating, but local climatic conditions have a very
important influence on design of successful low energy earth structure.
In his book “The Rammed Earth House”, David Easton summaries the very basic
principles of good architectural design as a response to the local climate, as follows:

in hot humid climates, provisions for wide porches and large screened windows with
cross ventilation should be made;

in hot dry climates, thick walls, small windows and night-time ventilation should be
utilized in order to reduce cooling loads by using the thermal mass of the walls to
counteract daytime heat gains;
in climates where the demand for winter heating exceeds that for summer cooling
and the winter days are typically clear and sunny, large south-facing windows (in
the northern hemisphere) and thermal mass floors should be used to reduce
heating loads; and
in regions where winters are long, cold and grey the best approach is to build small
well-insulated buildings with low ceilings and a minimum of exterior wall surface
exposed to the weather.


Vaults and domes earth buildings constructed around the world have demonstrate some
advantages in hot and dry climates, especially in areas with a wide range of diurnal
temperatures. The greater heights at the centre of a space, where light, warm air gathers
and can be easily discharged through openings, vaulted spaces provide better natural
climatic control than standard rectangular buildings. They have smaller surface areas
than cubic rooms of the same volume, and therefore less heat gain. In cold and moderate
climates as well, vaults and domes have several advantages. As the surface area is
smaller for the same volume, heat loss is lower, so heating energy is reduced. In all
developing countries, vaults and domes are usually cheaper in comparison with flat or
slightly inclined roofs. Researchers have shown that rooms with vaults and domes have a
pleasing and calming effect on inhabitants in contrast to rooms with flat ceilings.
As a result becomes necessary to store solar heating gain by passive means, soil can
balance indoor climate in the areas with diurnal temperatures differences.
Another important fact when we are talking about energy is the solar orientation of the
building which contributes to comfort of the house. Buildings should be designed in order
to trap the heat of winter sun, also providing much needed shading during the summer
months. According to Standard Australia (2002) the building’s longitudinal axis should be
aligned east-west and the north face (south face in the northern hemisphere) should be
20 Earth-a new look at an old material
most heavily glazed (equivalent of 15% 20% of the floor area) to allow the warmth of the
winter sun to enter the building , this applies only for this continent.
The benefits of appropriate orientation of the structure with respect to the direction of the
sunlight can result in reduced energy bills by as much as 80% (David Easton- “The
Rammed Earth House”). The environment created by natural heating is healthier than
artificial systems.
Figure 15.Thermal conductivity
Despite of facts against earth architecture I will like to emphasize a few of the most
important earth architecture “jewelries” in my opinion, which can give a lot of knowledge
about these structures.
21 Earth-a new look at an old material
Ecohotel “Friend House” is located on 3 hectares plot in forest resort zone aside of
Orel river bank, 30 km far from Dnepropetrovsk, Ukraine. It is a single-floor group of
buildings with open yards, parking, terraces, garden and park zones (covered area 1750
square meters). During process of sitting, an ideological analysis of the region was used,
taking into account Earth energy -information field conception. It is space, reflected in
details, surrounded by wildlife.
In this project were used exclusively ecological harmless materials: clay, reed and wood.
Construction’s carcasses designed from wood and shell stone. Cob work cocoons of room
are united by the roof plate. Intercommunicating with an environment – with forest, river,
the eco-cover of the buildings is in harmony with natural landscape.
Figure 16 a). Dnepropetrovsk, Ukraine Hotel
Figure 16 b). Dnepropetrovsk, Ukraine Hotel
Another earth house is this adorable little cob cabin mimics the style often seen in
England but is actually located in Mayne Island, Canada. It features the smooth
surfaces, curved walls and archways so typical of cob architecture. Some modern
elements are included as well, such as the prefabricated windows.
Figure 17. Earth house-Mayne Island, Canada
22 Earth-a new look at an old material
By far the most impressive construction in my opinion is Earth House Estate
Lättenstrasse from Dietikon, Switzerland design by the Swiss architect Peter Vetsch.
This settlement finds itself in contrast to the surrounding of traditional single houses. The
earth- covered houses are grouped centered around a small artificial lake with the
entrance well hidden and integrated at the side of the settlement. The isolation consists
of recycled glass, an absolute environment friendly product. The water protection is
added directly on the sprayed concrete. On top of the isolation is a protective layer with
natural earth, which can be used to grow grass or plants on the rooftop.
Figure 18. Earth House Estate Lättenstrasse- Dietikon, Switzerland
23 Earth-a new look at an old material
Measures to improve the characteristics of earth:
Although measures to improve the durability of earth as a building material, as well as
building techniques with earth with very low level of risk of failure, have been well
documented, it is always worthwhile to study traditional building practices in a particular
area.
Problems with earth buildings can generally be avoided by regular maintenance noting
any parts of the building which have become weakened or eroded and immediately
repairing them before any more serious problems develop. As all building materials earth
is exposed to bad weather condition, but researchers solve it according with the specific
problem.
Shrinkage:
Figure 19. Wall shrinkage
Earth building materials containing clay, swell on contact with water and shrink on drying.
In both cases failure might occur. Type, amount, soil grading and moisture content
changes this facts. Shrinkage during drying depends on water content, on the kind and
amount of clay minerals present, and on the grain size distribution of the aggregates.
This phenomenon can be avoided by addition of sand (1 or 2 mm) or larger aggregates in
the mix. In the ceramic industry, fluid thinning mediums are used to obtain higher
liquidity, thereby allowing less water to be used (in order to reduce shrinkage).
The shrinkage can be reduced also by the addition of fibers such as animal or human
hair, fibers from coconuts, palm fiber, sisal, agave or bamboo, trees and cut straw. This is
attributable to the fact that relative clay content is reduced and a certain amount of water
is absorbed into the pores of the fibers. Because the fiber increases the binding force of
the mixture, moreover, the appearance of cracks is reduced. Fibers are used to improve
the thermal performance and bending and tensile strength of soil.
24 Earth-a new look at an old material
Another method to avoid shrinking of earth building component is to slow down the
drying time by covering somewhere where we can avoid the direct sun arrays, turned
upright.
Water erosion:
Figure 20. Water erosion-Biskra, Algeria
The performance of natural wall earth under driving rain cannot be readily predicted.
Despite of the tests made by different researchers there is little correlative data between
laboratory tests and field erosion. Building element erosion is different by various facts,
such as exposure, shelter and maintenance. Most common laboratory test made is the
dripping test and spray test which have been develop to determine the relative erosion
resistance of earth building elements.
The threat of water seepage occurs around areas where the waterproofing layers have
been penetrated. Vents and ducts emerging from the roof can cause specific problems
due to the possibility of movement. To avoid this difficulty, vents can be placed on other
sides of the building (besides the roof), or separate segments of pipes can be installed.
The threat of water seepage, condensation, and poor indoor air quality can all be
overcome with proper waterproofing and ventilation.
The most common operation to protect the wall against erosion is to apply a water
resistant coat of paint, which most of the times is not enough. Often cracks appear on the
surface of the wall, and then rain water penetrates the element causing swelling and
erosion.
Figure 21. Coat of paint on earth wall
25 Earth-a new look at an old material
Another method to prevent against rain water erosion a good solution is to mix the loam
with cement or bitumen as stabilizers. The stabilizers cover the clay minerals and prevent
water from reaching them and causing swelling.
Cement is used against rain water erosion when working with low amount of clay soil. If
the amount of clay in higher the quantity of cement added in the mix will be higher.
Because regular cement blocks are achieving the top strength after 28 days, the loamcement building elements should be protected against sun arrays, wind and time to time
sprayed with water, without hurrying the drying.
Portland cement is often used to reinforce earth blocks, but only a small amount should
be added to reinforce the brick. Too much cement makes the brick heavy and reduces
moisture movement.
High levels of cement stabilization improve the surface coating and reduce erosion while
increasing the cement has a considerable influence in improving the resistance of soils
vulnerable to frost attack.
Cement is typically used in proportions between 4% and 15%, with between 6% and
10% the most commonly specified.
Figure 22. Loam and cement
Another finish which is more expensive and more permanent is which can be used as a
low-maintenance finish, but doesn’t accommodate for the breathing of the walls as much
as mud plaster. Stucco contains and traps the moisture instead of releasing it at a later
time, which leads to problematic issues. When using stucco, it is necessary to using
netting in order accommodate for the settling and cracking of the stucco.
Figure 23. Stucco netting
26 Earth-a new look at an old material
The membrane layer is often used a thick flexible polyethylene sheeting called EPDM.
EPDM is the material usually used in water garden, pond and swimming pool construction.
This material also prevents roots from burrowing through the waterproofing. EPDM is very
heavy to work with, and can be chewed through by some common insects like fire ants. It
is also made from petrochemicals, making it less friendly to environment.
Figure 24 a). Stucco netting and EDPM
Figure 24 b). Final covering
Slaked lime is pulverized limestone that expands and gets hot when wetted. When
calcium oxide reacts with water, it liberates heat and cracks into a white powder. This
white powder is calcium hydroxide or slaked lime. The process is called slaking of lime.
Slaked lime mixes with high clayey soils and makes a stronger earth element mixed with
soil. It also decreases moisture movement and permeability.
Figure 25. Slaked lime
27 Earth-a new look at an old material
Lime plaster is a type of plaster which is composed of hydrated lime. Lime plaster is
almost similar to lime mortar but the difference is mainly based on their use other than
its composition. Mainly lime plaster is a mortar which uses pure lime and sand as a binder
and aggregate respectively. But sometimes lime plaster can also be referred to as
gypsum or cement plaster. Basically lime plaster is a mixture of sand and calcium
hydroxide. There will be change in chemical properties of lime plaster like reducing the
elasticity, vapor exchange capacity; durability is due to the addition of cement to the
lime.
Figure 26. Lime plaster
The use of bitumen for waterproofing and as an adhesive dates at least to the third
millennium BCE where it was used to line the baskets in which they gathered crops. In
Babylon, bitumen was used to stabilize mud bricks as early as the 5th century AD.
After is dissolved in water with an emulsifier such as naphtha a film is formed that glues
the particles of loam together, typically is painted as a waterproof render to protect the
wall driving rain. Bitumen is added in the form of an emulsion that is in suspension in
water or another liquid medium. The main effect of adding bitumen is to improve
cohesion and water resistance. However, if it is added in excess the compressive strength
can be reduced.
Figure 27. Bitumen painted wall
28 Earth-a new look at an old material
A number of products from animals have been used as additives and binders during
centuries to earthen buildings. Used properly manure and blood, can improve hardness
and water resistance. Manure from cows and horses are the most common and still in use
additive in earth plasters. After laboratory tests Gernot Minke in his book says “a sample
with 3.5% by weight of cow dung began showing signs of erosion only after four hours”.
In Africa fresh manure is spread to create a floor which is often sealed with ox blood. Also
in the coastal areas shells have been used when people build houses and in some cases
are burned to make lime. In Northern Europe shells are being used for insulation and
drainage below floors.
Other organic additives used derived from animals or plants are: eggs, milk, linseed, oils,
cactus juice, starch, tallow, wheat flour paste, tree sap, molasses.
Figure 28 a). Shells
Figure 28 b). Linseed
Figure 28 c). Starch
Figure 28 d). Tallow
Figure 28 e). Tree sap
Figure 28 f). Molasses
Specially formulated chemicals have been developed for soil stabilization. The best known
are silicates, sodium silicates, soluble in water, ethyl silicate, potassium and calcium
silicate. All known synthetic substances have a stabilizing effect on loam also act as vapor
barriers. Soil properties will dictate need and there are many examples across the world
of the effective use of unsterilized soil. Stabilizers also are very expensive. Before using
any kind of synthetic stabilizer is deemed necessary to run some laboratory tests.
29 Earth-a new look at an old material
Improving thermal insulation:
For earth buildings the most common concerns raised related to thermal insulation of the
walls. Usually for earth buildings insulation is on the exterior wall, not as the conventional
building on the inside. The reason for this is that it provides protection for the waterproof
membrane against freeze damage, another is that the earth shelter is able to better
retain its desired temperature. In this case it is to keep the heat generated, collected,
and absorbed inside the interior of the construction. This reduces the summer cooling
effect of the walls, but prevents the walls from cooling down. For example in his
published book Gernot Minke is saying, an 30 mm thick rammed earth wall without
lightweight aggregates has a U-value of 1.9 to 2.0 W/m2K. To go down up to 0.5 W/m2K,
necessary in many European countries, a thickness of 1.6 to 1.8 m would be required. In
this case some additional insulation is required. Some types of insulation are describe
below:
Insulating render:
Insulating render is cement based wall render incorporating insulation material, applied to
the exterior of earth wall homes to improve insulation. Unlike, internal wall insulation,
insulating render does not affect room size of the building, but is losing characteristic
appearance externally which usually people prefer to keep it as it is.
Hemp lime, made from hemp or hemp mixed with either recycled cotton fibers or wood
fibers, bound with a polyester binder and treated for fire resistance. Hemp insulation is
used in breathing wall construction, ventilated pitched roofs and in ceilings and floors.
Hemp can be also mixed with loam and applied on the wall.
Figure 29. Hemp Lime insulation
30 Earth-a new look at an old material
Cork insulation, is obtained from the cork oak a forest tree with the particular feature of
allowing itself to be stripped of the outer casing which it then regenerates. The bark is
stripped first when the tree is 20 to 30 years old, after stripping take place every 9 to 10
years. Cork insulation is used in flat roofs and insulated render systems as earth walls.
Cork loam can be used to form light weight bricks. The cellular structure makes cork light
in weight, resistant to the penetration of moisture, and an ideal thermal and sound
insulation material, but very easy to brake. The disadvantage is that this material is
relatively expensive.
Figure 30. Cork insulation
Cellulose insulation consists almost completely of recycled newspapers. Some
manufacturers will also add a small amount of shredded cardboard. To make it stick
together with more efficiency, most will also add a binding, non-toxic chemical mixture,
to keep the cellulose insulation from bursting into flames; it is also treated with fire
retardants.
Cellulose insulation is usually spray on the walls, but is almost always applied in a dry
form.
Figure 31 a). Cellulose insulation sprayed on wall
Figure 31 b). Cellulose insulation
31 Earth-a new look at an old material
Sawdust, wood shavings and chips can also be used as lightweight aggregates to
increase the thermal insulation capacities of loam. The disadvantages using this materials
in mix with loam is the risk of fungus growth and rotting.
Also the waste from saw mils can be soaked in water before being pressed and dried
without additional bonding agents. Wood fiber board insulation is typically used in
breathing wall construction as well as in roofs. This are called wet-formed wood fiber
insulation board.
Figure 32. Wood fiber insulation board
32 Earth-a new look at an old material
Conclusion:
The durability and versatility of earth constructions is demonstrated by traditional earth
buildings from all over the world. If we are talking about unpopularity of this structures
first idea is getting in my mind is the lack of knowledge especially of the people who are
working in this branch as architects, engineers and contractors. They should gain the
knowledge first of all and share to the potential clients according with their demands.
Another preconception is coming from the regular people which they could improve the
quality of living having such a harmonious house, but instead the ignorance is gained
after World War II. They couldn’t accept to live in medieval condition when the
abundance of construction materials rich the top denying it the value.
The facts as weather erosion and construction damage which require regular maintenance
are real according with the climate and quality of work. But as all the problems are also
ways to solve this. There are no technical reasons why earth materials should not be used
in contemporary architecture.
Structural design guidance for earth walls largely follow procedures developed for load
bearing masonry.
Taking in consideration the structural design in case of earthquake some recommendation
to improved seismic performance of earth construction are summarized below:
 Structure tied together
 Horizontal and vertical reinforcement
 Light well connected roof
 Good quality construction
 Regular and symmetrical shape
 Flat, firm dry site
The thermal insulations of the earth shelters can be increased to achieve the lowest Uvalue. Usually this involves using the thickest insulation possible, although higher
performance thin foils are available at a price. In making your selection choose insulation
derived from organic sources first (sheep wool, hemp fiber see above examples);
alternatively use insulation derived from naturally occurring minerals (glass, mineral
wool) or as a last resort insulation derived from fossil fuels (but ideally those that use
Zero-ODP blowing agents). Earth walls, floors, or earthen plasters also balance humidity
levels, possibly help filter impurities from air, and are generally of low toxicity. These
latter attributes are lost if the clay is neutralized by stabilizers, or given unsuitable
coatings, which do not allow it to breathe.
In my experience as a Constructing Architect I had the opportunity to work for and
outline proposal which required the use of earth as a main building material. The
disappointment came because I couldn’t physically work and build this project. This fact
didn’t put me down, but determine to continue the research (writing this report) and gain
more knowledge hopefully for further projects.
33 Earth-a new look at an old material
List of figures
Figure 1. Temple of Ramses II at Abu Simbel, Egypt ........................................................................... 7
Figure 2. Draa Valley-Marocco ......................................................................................................... 7
Figure 3. Great Wall of China ........................................................................................................... 8
Figure 4. Citadel of Bam- Iran ......................................................................................................... 8
Figure 5.b) Shibam, Yemen ............................................................................................................. 8
Figure 6.Weilburg, Germany ............................................................................................................ 9
Figure 7.France, Reyrieux-Castle XVIII century ................................................................................ 10
Figure 8. Frank Lloyd Wright rammed earth house ............................................................................ 10
Figure 9. Romania, Danube Delta-Making adobe bricks...................................................................... 11
Figure 10.a) Group of people mixing cob with feet ............................................................................ 12
Figure 11. b) Hand operated press ................................................................................................. 13
Figure 12. b) Hand operating ramming pole ..................................................................................... 14
Figure 13. b) Ghana, Ashanti Region art village-personal project ........................................................ 15
Figure 13. a) Earth bags with barbed wire ....................................................................................... 15
Figure 14.Minimum thickness of wall.............................................................................................. 16
Figure 15. Thermal conductivity......................................................................................................18
Figure 16. a). Dnepropetrovsk, Ukraine Hotel………………………………………………………………………………………………..19
Figure 16. b). Dnepropetrovsk, Ukraine Hotel………………………………………………………………………………………………..19
Figure 17. Earth house-Mayne Island, Canada……………………………………………………………………………………………….19
Figure 18. Earth House Estate Lättenstrasse- Dietikon, Switzerland…………………………………………………………….20
Figure 19. Wall shrinkage.............................................................................................................21
Figure 20. Water erosion-Biskra, Algeria……………………………………………………………………………………………………….22
Figure 21. Coat of paint on earth wall……………………………………………………………………………………………………………22
Figure 22. Loam and cement………………………………………………………………………………………………………………………….23
Figure 23. Stucco netting……………………………………………………………………………………………………………………………….23
Figure 24 a). Stucco netting and EDPM…………………………………………………………………………………………………………24
Figure 24 b). Final covering…………………………………………………………………………………………………………………………..24
Figure 25. Slaked lime…………………………………………………………………………………………………………………………………..24
Figure 26. Lime plaster………………………………………………………………………………………………………………………………….25
34 Earth-a new look at an old material
Figure 27. Bitumen painted wall…………………………………………………………………………………………………………………..25
Figure 28 a). Shells……………………………………………………………………………………………………………………………………….26
Figure 28 b). Linseed………………………………………………………………………………………………………………………………………26
Figure 28 c). Starch………………………………………………………………………………………………………………………………………..26
Figure 28 d). Tallow....................................................................................................................26
Figure 28 e). Tree sap……………………………………………………………………………………………………………………………………26
Figure 28 f). Molasses……………………………………………………………………………………………………………………………………26
Figure 29. Hemp Lime insulation………………………………………………………………………………………………………………….27
Figure 30. Cork insulation…………………………………………………………………………………………………………………………….28
Figure 31 a). Cellulose insulation sprayed on wall………………………………………………………………………………………28
Figure 31 b). Cellulose insulation………………………………………………………………………………………………………………..28
Figure 32. Wood fiber insulation board……………………………………………………………………………………………………….29
35 Earth-a new look at an old material
Reference list
http://www.scribd.com/doc/35204615/Earth-Building-Around-The-World
http://www.earthbagbuild.com/brief_history.htm
http://www.siteground128.com/~rammedea/index.php?option=com_content&task=view&id=50
http://madamekunterbunt.net/buildinggreen/downloads/files/HANDOUT_LECTURE2.pdf
http://www.scribd.com/doc/28577005/Building-With-Earth-Design-and-Technology-of-a-SustainableArchitecture-Gernot-Minke-Birkhauser
http://weblife.org/cob/
http://ceramica.wikia.com/wiki/CeraWiki:Imagen_del_d%C3%ADa/enero_de_2008
http://www.cobcottage.com/questions
http://en.wikipedia.org/wiki/Cob_%28material%29
http://www.cultureartist.org/cob.htm
http://www.appropedia.org/Compressed_earth_brick_press
http://www.openplanetideas.com/how-can-sony-technology-be-used-to-address-environmentalchallenges/concepting/back-to-basics/
http://abari.org/rammed-earth
http://greenupgrader.com/2156/rammed-earth-home-building-with-compressed-dirt/
http://en.wikipedia.org/wiki/Earthbag_construction
http://www.earthbagbuilding.com/articles/stepbystep.htm
http://ontheworktable.blogspot.com/2011/02/fw-how-to-build-earthbag-dome.html
http://www.umbugjug.com/wp-content/uploads/2010/02/green-building.jpg
http://staff.bath.ac.uk/abspw/rammedearth/review.pdf
A Review of Rammed Earth Construction for DTi Partners in Innovation Project ‘Developing Rammed Earth
for UK Housing’ May 2003 Prepared by:Vasilios Maniatidis & Peter Walker Natural Building Technology
Group Department of Architecture & Civil Engineering University of Bath Bath BA2 7AY
http://arab-training.com/vb/t14975.html
http://www.buildingwithawareness.com/Picturetour1.html
http://4.bp.blogspot.com/_qN781YJ7_mU/ScguSBn9sMI/AAAAAAAAAus/H-Zk50AbDGA/s1600h/HG+House,+Stucco+Brown+Coat+and+fireplace+scratch+coat+011.jpg
http://en.wikipedia.org/wiki/Earth_sheltering#Waterproofing
https://picasaweb.google.com/graham.bowkett/Glenhaven#5132783857088818818
http://www.tutorvista.com/content/chemistry/chemistry-ii/chemical-compounds/slaked-lime.php
36 Earth-a new look at an old material
http://en.wikipedia.org/wiki/Lime_plaster
http://www.naturalbuildingsite.net/plaster.html
http://epress.lib.uts.edu.au/dspace/bitstream/handle/2100/241/02Chap1toChap4.pdf?sequence=2
http://en.wikipedia.org/wiki/Bitumen#Uses
http://www.myttc.net/ http://books.google.com/books?id=054_i8KdcCAC&pg=PA99&lpg=PA99&dq=manure+used+in+earth+cons
truction&source=bl&ots=4VzMWlwsYF&sig=86DCQ0W-mVZ1HRD-x6hyvkNOyo&hl=en&ei=Qti_TZHlJIqSswbA3qnDBQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CBcQ
6AEwADgK#v=onepage&q=manure%20used%20in%20earth%20construction&f=false
http://jontybarrett.wordpress.com/vernacular/hemp-lime-construction/
http://www.greenspec.co.uk/insulation-plant-fibre.php#hemp
http://www.corkstore.eu/products/cork-in-building-industries/insulating-cork-sheets/
http://www.cork-insulation.com/
http://mdinsulation.com/insulation.htm
http://www.5rbi.ca/ http://www.moma.org/interactives/exhibitions/2010/smallscalebigchange/projects/meti_handmade_school http://www.ecomerchant.co.uk/content/steico‐therm‐wood‐fibre‐insulation‐board http://webecoist.com/2009/02/02/earthen-architecture-natural-dirt-mud-brick-buildings/
http://www.erdhaus.ch/main.php?fla=y&lang=en&cont=earthhouse