CE
DA
CT
erra
CEB Dossier
VALE DAS LOBAS
Sobral Pichorro - Fornos de Algodres
MIGUEL ROCHA, arch.
CEDACTerra – Badajoz
March, 2017
CEB IMPLEMENTATION REPORT - Vale das Lobas 3
CONTENTS
INTRODUCTION 5
Scope
Earth construction
1. COMPRESSED EARTH BLOCKS - CEB 9
1.1. Definition
1.2. Historical background
1.3. CEB Production
2. ADVANTAGES OF CEB 15
3. SUSTAINABILITY AND ENVIRONMENTAL FRIENDLINESS 21
3.1. Green-building and human health
3.2. Cost and energy effectiveness
4. TECHNICAL DATA AND PERFORMANCES 23
4.1. Soil/raw material
4.2. CEBs characteristics
4.3. Earthquake resistance
5. CEB STANDARDS 27
5.1. International standards
5.2. Product datasheets
6. RESEARCH CENTERS AND EARTH BUILDING ENTITIES 33
ANNEXES 39
CEB IMPLEMENTATION REPORT - Vale das Lobas 5
INTRODUCTION
SCOPE
In the middles of 20th century a new building technique has been developed:
Compressed Earth Block, named as CEB. Since then, CEB building technique and
its technology was far improved and gained popularity in many countries
worldwide.
Towards a better understanding of CEB relevance, the quality and performances of
the product and the value and durability of buildings made with this material, this
document has been elaborated by CEDACTerra, to provide a global view on CEB
technology and some technical data, regarding the future development of Vale das
Lobas project. All the facts and technical information stated herein are grounded
on academic scientific research, recognized by building authorities and endorsed
by the good results of the practice of this type of construction, all over the world.
EARTH CONSTRUCTION
Earth as building material has been used worldwide since the dawn of humankind.
It is one of the oldest construction materials.
Building with earth means to build with a material that is under our feet and that we
step on every day: the soil. However, soil can only be used for construction
purposes when it offers a good internal cohesion that is mainly given by the
presence of clay, which acts as a natural binder.
One of the world’s oldest earthen building still standing is about 3.300 years old:
the Granaries of the Ramasseum, in Egypt, which has been built with sun-dried
bricks (adobes) by Ramses II, of the 19th dynasty, around 1.300 BC in a place
called Western Thebes. It can still be seen a few kilometres from the western shore
of the Nile, opposite Luxor.
CEDACTerra | Miguel Rocha, arch. 6
Tabo Monastery, in Spiti valley - Himachal Pradesh, in India, is another of the
world’s oldest earthen buildings. It was also built with adobes, it has withstood
Himalayan winters since 996 AD, and it is still in use.
Used as a building material for 10.000 years, nowadays nearly 20% of the world
population is still living or working in earth buildings. At the end of 20th century,
UNCHS Habitat evaluated that about 1.7 billion people of the world live in earthen
houses: about 50% of the population in developing countries, and at least 20% of
urban and suburban populations. In addition, UNESCO states that 17% of the
“world cultural heritage sites” are made of earth.
Fig. 1 – Earth architecture and construction in the world.
There are twelve principal well-known methods using earth as a building material.
Amongst these, eight are currently employed and constitute the major techniques.
Adobe: the earth, in a malleable state, often improved by addition of straw
or other fibres, is moulded into a brick form and dried in the sun. (11, 12,
13)
Rammed earth: the earth is massively dumped into formworks,
compacted by means of a rammer, layer by layer, and formwork by
formwork. (5)
Straw clay: the earth is spread out in water until a homogeneous thick
liquid state is attained. This muddy liquid is mixed with straw in order to
form a film on every wisp. The building material obtained conserves its
straw-like aspect. It is put into place by means of a formwork in order to
erect a monolithic wall which necessitates a primary support structure.
(16)
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Wattle and daub: clayey material, mixed with straw or other fibres, is
layered on top of wattles that fill in a timber structure. (14, 15)
Shaped earth: the earth, often improved by addition of straw or other
fibres, is shaped into a wall using the same technique as that used for
pottery, without tools. This ancient technique is still widely used. (4)
Extruded earth: the earth is extruded by a powerful machine similar to, or
derived from, the machines used for the manufacture of fired brick. (10)
Cob: the earth, often improved by addition of straw or other fibres, is
shaped into big balls, which are piled on top of one another and lightly
packed, by hand or tool, in order to erect shaped monolithic walls. In other
cases, the cob is incorporated into a timber framework or structure. (3)
Compressed earth: the earth is compressed, in block form, in a mould.
In the past, the earth was compressed in the mould by means of a small
pestle, or by tamping a very heavy lid forcefully on the mould. Nowadays,
a wide variety of presses is used. (6, 7)
Fig. 2 – Earth construction methods.
In Portugal the main earth construction techniques traditionally used are wattle &
daub (14), adobe (12) and rammed earth (5).
CEB IMPLEMENTATION REPORT - Vale das Lobas 9
1. COMPRESSED EARTH BLOCKS - CEB
1.1. DEFINITION
Compressed earth block is a new development in modern times, as it combines
the ancestral techniques of adobes (sun dried earth brick) and rammed earth.
Instead of being moulded by hand, or with rammers, in a wooden frame, the blocks
are formed by compressing raw earth, slightly moistened, in a mechanical steel
press. This compression makes it possible to subtract the air in the block in order
to waterproof it and to increase its resistance. Compared to adobe and other hand
moulded blocks, the CEB is very regular in size and shape, and much denser. It
has better resistance to compressive stress and to water.
1.2. HISTORICAL BACKGROUND
The first attempts for compressed earth blocks were made in the early days of the
19th century in France. The architect François Cointeraux 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: it was the “new pisé”. Besides, he develops the
"Crécise", a brick press derived from a wine press. With this earth materials he
built the town of La Roche-Sur-Yon on the orders of the Minister of the interior of
Napoleon I from 1804 to 1808.
Fig. 3 – Compressed earth blocks, manually rammed. François Cointeraux, 1803, France.
CEDACTerra | Miguel Rocha, arch. 10
The first steel manual press was the "Cinvaram", which was the result of a research
programme conducted in the 1950’s by the engineer Raul Ramirez from the
Colombian Inter-American Housing Center (CINVA). This press could get regular
blocks in shape and size, denser, stronger and more water resistant than the
adobe.
Fig. 4 – Original CINVA Ram press.
Since then, many more types of machines have been designed and many
laboratories got specialised and skilled to identify the soils for buildings. Many
countries in Africa as well as South America, India and South Asia have been using
this technique. Europe and USA also show a lot of interest for this technology.
Africa has seen the widest development and implementation of CEB since the
1960's. Nearly every African country has examples of CEB building, from- social
housing to luxurious apartments and government buildings.
CEB IMPLEMENTATION REPORT - Vale das Lobas 11
In India one of the first institutions to research and develop this technology was the
Central Building Research Institute (CBRI) at Roorkee, which has been conducting
research since the 1970's. The Indian Institute of Science of Bangalore (IISc) has
also done a lot of research on this subject. The Auroviile Earth Institute (AVEI) has
done extensive applied research and development on CEB and various stabilised
earth techniques which are being disseminated and used worldwide.
South Asia also shows a lot of development and use of CEB. In Thailand the initial
research was undertaken by the Thailand Institute of Scientific and Technological
Research (TISTR) at Bangkok in the 1960s. They used the Cinvaram press and
developed interlocking blocks.
Sri Lanka also uses more and more this technology and the Sri Lankan Standard
Institution is on the way to publish their standard on the production and use of CEB.
New Zealand and Australia have also standards related to earth techniques which
include compressed stabilised earth blocks.
In USA the State of New Mexico has published standards including CEB and other
earth techniques. Several other states are also using CEB and other stabilised earth
techniques. Contractors are building with CEB in Colorado, Texas and New Mexico
and the demand is increasing in other US states.
Europe also sees more and more development with earth techniques. There are
networks in Germany, France and Switzerland. In France, CRAterre-ENSAG
promotes CEB, all kinds of earth techniques and is the Centre of excellence of the
UNESCO Chair "Earthen Architecture, Constructive Cultures and Sustainable
development".
During the first decade of the 21st century CEB technology, has risen throughout
the world as a material with sustainable properties, low environmental impact and
great eco-design capacity. There has been a growth in projects and research on
this material related to the increase in the number of associations, institutions,
universities and events around this sector. The current projects have been able to
modernize the traditional techniques of earth construction, in order to adapt them
CEDACTerra | Miguel Rocha, arch. 12
to design and constructive needs, being widely recognized for their quality, and
CEB is a great example of it.
1.3. CEB PRODUCTION
CEBs are produced with a mixture of non-vegetable soil composed of gravel, sand,
and fine elements (silt and clay). Depending on its natural characteristics, a binder
aggregate (cement or lime in most cases) can be added to the soil to improve its
characteristics. Brick presses are then used to compress that earth mixture:
manual or motorized, with mechanical, hydraulic or pneumatic transmission. The
soil, raw or stabilized, is slightly moistened, poured into the press and then highly
compressed.
Fig. 5 – A standard compressed earth block.
Machinery for compressed earth blocks has evolved a lot and nowadays it is
possible to find manual presses as well as motorised ones, mobile units and
completely integrated plants and CEBs can be produced in many different shapes
and sizes.
CEB IMPLEMENTATION REPORT - Vale das Lobas 13
Fig. 6 – CEB can be produced in many different shapes and sizes.
Compressed earth blocks can be produced in small scale village workshops as
well as in medium or large scale urban plants. They are of regular shape and size,
making the production of fine masonry easy. The CEB can be used in prestigious
buildings as well as social building programmes.
Given their cost, the vast majority of brick presses are manual. However, the quality
of the raw clay blocks produced with a manual press is not as satisfactory as with
a hydraulic press because the pressure exerted on the earth mixture is stronger.
But above all, the dimensional regularity of the bricks is very clear, which makes
the setting in work simple and reliable.
Fig. 7 – Hydraulic press producing CEB.
CEDACTerra | Miguel Rocha, arch. 14
Between traditional and low grade techniques and imported modern materials, the
CEB provides an alternative and its production may constitute a first step in setting
up a national industry in the building materials sector, using national labour and
local resources. Combining engine and hydraulic presses offer blocks that are quite
competitive with common ceramic bricks.
The compressed earth blocks are an environmentally friendly material that allows
to build up to two/three floors, depending on the quality of the compression and
the soil used. CEBs can be used in almost all the countries of the globe: except for
very rare exceptions, the material of the subsoil is mechanically and chemically
capable of being compressed.
Fig. 8 – CEB three storey building, in Auroville.
CEB IMPLEMENTATION REPORT - Vale das Lobas 15
2. ADVANTAGES OF CEB
Compressed earth blocks have great advantages: they are in most cases cheaper
and they are always more eco-friendly than concrete blocks or kiln-fired bricks.
A local material
Ideally, the production is made on the site itself or in nearby areas. Thus,
it will save transportation, fuel, time and money.
An adapted material
Being produced locally it will be easily adapted to the various needs of the
people: technical, social, cultural habits.
A transferable technology
It is a simple technology requiring semi skills easy to get. Simple villagers
will be able to learn how to do it in few weeks. Efficient training centre will
transfer the technology easily in a week time.
A bio-degradable material
With minimum maintenance, well-designed CEB houses can withstand
heavy rains, snowfall or frost without being damaged. The strength and
durability has been proven since more than half a century. But let us
consider a fallen down or demolished CEB building and vegetation grown
over the debris: bio-chemicals contained in the humus of the topsoil will
destroy the soil cement mix in 10-20 years. And CEB will come back to
Mother Earth. No other building material can do that!
Improving traditional techniques
Where there is a demand of improving traditional building materials made
of raw earth, CEB may provide an answer because the production
methods are technically accessible to the local labour, and because laying
CEB requires only elementary mason skills.
CEDACTerra | Miguel Rocha, arch. 16
Building programs
Setting up large scale building programs or building in urban areas means
using standard designs for the houses. Standardized building materials of
known size and tested quality such as CEB are used for construction. And
if the houses have been designed using a modular system consistent with
the CEB size and shape, much time and money can be saved.
Fig. 9 – Apartments complex, built with CEB, in Colombia.
Building techniques
The CEB is a very practical building material suitable for a beam-and-post
system as well as for a load bearing wall system. It is easy to make arches
over openings to save on concrete or wooden lintels. When the blocks are
laid properly and the outside of the walls is not too exposed, the wall does
not need any rendering. The CEB is economical not just in itself but also
because it makes the application of eco-building techniques and design
possible.
CEB IMPLEMENTATION REPORT - Vale das Lobas 17
On the building site
The standardized shape and size of the CEB make storage, handling and
bricklaying easy. Saving time means saving money. The CEB facilitates
savings on the general management of a construction site.
Fig. 10 – CEB standardized shape make storage easy and is compatible with modern construction
means.
Reducing imports
In regions and countries where building materials like cement have to be
imported and transported over long distances or under difficult conditions,
the local production of CEB by semiskilled people is often an economically
attractive alternative.
Management of local resources
Produced locally, each quarry can be planned to be used as water
catchments, wastewater treatment, reservoirs, landscaping, etc. It is
crucial to be aware of this point: very profitable if well managed...
disastrous if unplanned!
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Market opportunities
Financially, the profit to be earned from local CEB production depends on
the local situation and context: the cost of the raw material, labour,
stabilizer, equipment buying/renting, etc. A feasibility study has to be
carried out to establish an accurate profitability of a CEB production unit
in every particular case. But in most cases, CEB buildings are cheaper
than buildings made of sand cement blocks.
Flexible production scale
CEB production equipment exists for the small scale as well as industrial
scale units, thus, CEB can be used in a wide variety of contexts. Equipment
for CEB are available from manual to motorized tools ranging from village
to semi-industrial or industrial scale. The selection of the equipment is
crucial, but once done properly it will be easy to select the most adapted
equipment to each context to produce for the required scale.
Limiting deforestation and energy resources
In regions where building involves materials produced using firewood or
fossil fuels, the CEB contributes to limiting deforestation and the use of
polluting fuels. Fire is not needed to produce CEB. Thus it will save the
forests and other natural resources, which are being depleted in the world,
due to short view developments and mismanagement of resources.
Fig. 11 – CEB houses, in the forest.
CEB IMPLEMENTATION REPORT - Vale das Lobas 19
Social acceptance
In its early stages, the CEB was associated with social housing or village
housing i.e. habitat for the low income population or the poor. Since that
time, it has been convincingly demonstrated that the CEB can adapt itself
to various needs and also be introduced in buildings such as houses for
the better-off. Compared to traditional materials, the CEB is a vast
improvement.
Cost efficiency
Produced locally, with a natural resource with semiskilled labour, almost
without transport, it will be definitely cost effective! More or less according
to each case and one’s knowledge!
Energy efficiency and Eco friendliness
Requiring only a little stabilizer (thus little fuel for it) the energy
consumption in a m3
of CEB can be from 5 to 15 times less than a m3
of
fired bricks. The pollution emission will also be 2.4 to 7.8 times less than
fired bricks.
A job creation opportunity
This technology allows unskilled and unemployed people to learn a skill,
therefore get a job and rise in the social values.
Fig. 12 – CEB houses in a residential complex, in Brazil.
CEB IMPLEMENTATION REPORT - Vale das Lobas 21
3. SUSTAINABILITY AND
ENVIRONMENTAL FRIENDLINESS
3.1. GREEN BUILDING AND HUMAN HEALTH
Earth is one of the most popular materials amongst Europe’s bio-ecological
constructors because of its physical attributes and ability to regulate moisture,
temperature and the quality of the air inside the houses. CEB technology offers a
cost effective, environmentally sound masonry system.
Like any construction with raw clay, CEB is a good thermal insulator, but is
especially endowed with a great inertia in the exchange of heat. In a building made
with these earth blocks there are several factors that enhance the feeling of living
in harmony with the environment:
- CEBs regulates the humidity of the atmosphere (hygrometry) and thus
avoids the appearance of mould and dust;
- its inertia provides a diffuse and beneficent heat in the winter and a
sensation of freshness in the summer;
- its colours are warm and lively;
- its density offers a high absorbing power which attenuates the
reverberation of sounds and installs a calm and soothing atmosphere;
- they absorb odours and dust;
- they are non-allergenic, because CEBs are made with natural elements
and avoid inflammation of the mucous membranes, asthma...
- they attenuate the electromagnetic fields.
3.2. COST AND ENERGY EFFECTIVENESS
Compressed earth blocks are a cost and energy effective material. As no fire is
required for its production, most of the times CEB are cheaper than fired bricks and
concrete blocks. Yet, costs breakup are always adapted according to each local
context.
CEDACTerra | Miguel Rocha, arch. 22
Energy effectiveness, among other aspects, comes from:
earth is a local material and the soil should preferably extracted from the
site itself or not transported too far away.
earth construction is a labour-intensive technology and is an easily
adaptable and transferable technology.
it is much less energy consuming than fired bricks (5 or 15 times less).
it is much less polluting than fired bricks (2.4 or 7.8 times less).
A study from Development Alternatives (New Delhi - 1998) gives per m2
of finished
wall:
WALL MATERIAL ENERGY CONSUMPTION POLLUTION EMISSION (CO2)
Compressed Earth Blocks (CEB) 110 MJ / m2 16 Kg / m
2
Kiln Fired Brick (KFB) 539 MJ / m2 39 Kg / m
2
Country Fired Brick (CFB) 1657 MJ / m2 126 Kg / m
2
Plain Concrete Blocks (PCB) 235 MJ / m2 26 Kg / m
2
Notes:
- Kiln Fired Bricks are also called Kiln Burnt Bricks or Wire Cut Bricks
- CSEB consume per m2 5 or 15 times less energy than fired bricks and 2,1 times less energy than plain concrete blocks.
- CSEB pollute per m2 2,4 or 7,8 times less than fired bricks and 1,6 times less than concrete blocks.
SUMMARY
MONETARY COST ENVIRONMENTAL COST STRENGTH
CSEB and rammed earth always cost
less than fired bricks
CSEB and rammed earth are more
eco-friendly than fired bricks
CSEB and rammed earth are:
A finished m3 of CSEB wall is:
15.4 % cheaper than country fired bricks
43.5 % cheaper than wire cut bricks
Pollution emission:
2 times less than wire cut bricks
4 times less than country fired bricks
1.4 times stronger than country
fired bricks
A finished m3 of rammed earth wall is:
23.8% cheaper than CSEB wall
35.5 % cheaper than country fired bricks
57.0 % cheaper than wire cut bricks
Energy consumption:
2 times less than wire cut bricks
4 times less than country fired bricks
0.5 times weaker than wire cut
bricks
CEB IMPLEMENTATION REPORT - Vale das Lobas 23
4. TECHNICAL DATA AND
PERFORMANCES
4.1. CEB’S RAW MATERIAL
In the early stages of the development of the CEB technique, the attention of
researchers was focussed mainly on the strength of the blocks and the design of
presses. However, experience has shown the importance of other production
parameters such as selection and preparation of the soil.
As soil is the raw material for CEB production, it is easy to understand the
importance of deeply knowing its characteristics and suitability for construction
purposes. Top soil, which normally contains humus, is not used for CEB. It shall
be scraped aside and reused latter on for agriculture purposes and landscaping.
Sub-soil is where we can find the suitable soil for compressed earth blocks.
Nevertheless, finding the right soil is not so easy. But it is possible to use many
soils and to modify them, starting from its correct identification and then improving
or stabilising them.
Fig. 13 – Soil: the raw material for CEB production.
If improvements were traditionally made in an empirical way, nowadays soils can
be identified by laboratory analyses and tests in order to know exactly which class
of soil we have in each place and the right type of improvement or stabilization
method for it, if needed.
CEDACTerra | Miguel Rocha, arch. 24
4.2. CEB TECHNICAL DATA
TECHNICAL SPECIFICATIONS CEB
without stabilization
CEB
with stabilization
Dry compressive strength
(After 28 days curing)
30 to 60 kg/cm2
50 to 70 kg/cm2
Wet compressive strength
(After 28 days curing)
15 to 30 kg/cm2
(Test after 3 days immersion)
30 to 40 kg/cm2
(Test after 24 hours immersion)
Dry bending strength
(After 28 days curing)
5 to 10 kg/cm2
10 to 20 kg/cm2
Dry shear strength
(After 28 days curing)
4 to 6 kg/cm2
4 to 6 kg/cm2
Water absorption
(After 28 days curing)
8 to 12 %
(Test after 3 days immersion)
8 to 10 %
(Test after 3 days immersion)
Apparent bulk density (dry) 1700 to 2000 kg/m3
1900 to 2200 kg/m3
Thermal conductivity coefficient 0,87 W / m ºC 0,81 to 0,93 W / m ºC
Thermal lag (45 cm wall) 8 to 10 hours 10 to 12 hours
Warmth-resistance (45 cm wall) 0,35 K/W
Warmth-accumulation capacity 2000 KJ/m3
kl
Damp diffusion < 10
Acoustic insulation (45 cm wall) 56 dB
Energy consumption
Compare this value with Fired Bricks and Plain
Concrete Blocks (See 3.2)
110 MJ / m2
Pollution emission (CO2)
Compare this value with Fired Bricks and Plain
Concrete Blocks (See 3.2)
16 Kg / m2
Compared with other modern construction materials, the CEB can easily surpass
all standards for 2-3-storey buildings with load bearing walls. In fact, the history of
construction brings to us diverse examples of multi-storey buildings constructed
only with earth, which persisted for hundreds of years. Such is the case of the
town of Shibam, in Yemen, with 7.000 people, where the 16th century adobe
buildings rise up to ten storey, and they are still in use.
CEB IMPLEMENTATION REPORT - Vale das Lobas 25
CEB thermal performance is excellent and durability can be very good if the specific
building principles are respected. The energy involved in producing a CEB is very
low. In conclusion, CEB is a construction material with a very good building
performance.
Fig. 14 – CEB four storey building, in Auroville.
4.3. EARTHQUAKE RESISTANCE
The CEB technology has been demonstrated as an option for Disaster resistant
housing in UN-Habitat (Istanbul-Turkey), which was constructed by Auroville Earth
Unit. CEB technology was accepted by the government as a technology for
Disaster Resistance, in response to the Gujarat Earthquake (India- 2001).
There are interlocking CEB that can be manufactured with hand-operated
machines. The blocks are designed to include the structural details for earthquake
resistance in the masonry thereby making the structure a reinforced masonry.
CEB IMPLEMENTATION REPORT - Vale das Lobas 27
5. CEB STANDARDS
5.1. INTERNATIONAL NORMS AND STANDARDS
In many countries, all over the world, research and further development has been
done in the field of earth building norms, standards and technical manuals to
facilitate the introduction of CEB technique to the formal building sector.
The international panorama of the regulation for building with raw earth is already
very varied (around 100 documents) and there are regulations of very diverse
nature. Here’s a non-exhaustive list of international earth construction norms:
- Brazil NBR 8491, 8492
- Colombia NTC 5324
- USA NMAC, 14.7.4 / ASTM E2392 M-10
- India IS 2110, IS 1725
- Kenia KS 02-1070
- Nigeria NIS 369
- New Zealand NZS 4297, 4298, 4299
- Peru NPT 331.201, 331.202, 331.203 / NTE E 0.80
- Regional Africa ARS 670-683
- Sri Lanka SLS 1382-1, 1382-2, 1383-3
- Tunisia NT 21.33, 21.35
-Turkey TS 537, TS 2514, TS 2515
- Zimbabwe SAZS 724
Fig. 15 – CEB building under construction and finished.
CEDACTerra | Miguel Rocha, arch. 28
In most cases this type of documents refers to one or two techniques. Regulations
and norms that cover earth construction as a whole are generally not used.
The New Zealand set of standards presents a model comparable to the current
approach to other building materials, characterized by the good definition of the
target techniques, the abundant development of all phases of the process for the
three main techniques, and by the detailed description of the proposed test
procedures. For better understanding, here some information about the New
Zealand Aseismic Performance-Based Standards, Earth Construction,
Research, and Opportunities:
New Zealand Building Legislation
The New Zealand Building Act 2004 (New Zealand 2004) established a framework
of building controls and construction that must comply with the mandatory New
Zealand Building Code. Approved documents provide methods of compliance with
the Building Code, and New Zealand Standards are one way to comply with the
code.
The first such approved document for nonengineered construction was NZS 3604,
Code of Practice for Light Timber Frame Buildings Not Requiring Specific Design
(Standards New Zealand 1978). Timber is used in over 90% of New Zealand house
construction, so this established the precedent for this type of document. Earth
building standards have needed to provide a comparable level of detail to satisfy
the territorial authorities and builders familiar with NZS 3604. The latest version,
NZS 3604: 1999 Timber Framed Buildings (Standards New Zealand 1999) now
has four hundred pages with numerous tables and well-drawn diagrams that allow
builders and architectural designers to design houses to resist earthquake and
wind loads.
New Zealand Earth Building Standards
Three comprehensive performance-based standards for earth-walled buildings
were published in 1998. Substantial documents were needed for design and con-
struction that used a performance-based approach to comply with the general
standards framework. These have been approved as a means of compliance with
the New Zealand Building Code. The standards were prepared by a joint technical
committee of engineers, architects, researchers, and builders and were developed
CEB IMPLEMENTATION REPORT - Vale das Lobas 29
over a period of seven years. These documents have made a significant
contribution to the increased acceptance of earth building in New Zealand.
Following, a non-exhaustive reference to European earth construction norms:
- France AFNOR XP P 13-901:2001 > Compressed earth blocks for walls
and partitions: definitions - Specifications - Test methods -
Delivery acceptance conditions.
- Germany Lehmbaud Regeim
- Italy LR Ab. N. 17/97
LR Ab 15th February 2001
LR 2/06 2nd August 2006
- Spain UNE 41410:2008 > Compressed earth blocks for walls and
partitions. Definitions, specifications and test methods.
- Switzerland SIA-Document D0111
SIA-Document D0112
SIA-Document D077
For the proximity with Portugal, and due to the fact that CEDACTerra is based in
Spain, it is to emphasize the Spanish norm UNE41410:2008 - Compressed earth
blocks for walls and partitions. Definitions, specifications and test methods.
At the end of 2008, the first Spanish standard for earth construction was
developed, and it is the first non-experimental European standard for compressed
earth blocks, issued by AENOR subcommittee AEN / CTN 41 SC 10 "Building with
Raw Earth".
Due to the fact that there is no stable production of this material (CEB) in Portugal,
there is still no established market and, consequently, there is no specific national
standardization. This is not a constraint because, as stated above, at international
level we have an immense amount of technical information and standards that
support our work. Meanwhile, we will refer mainly to Spanish standard.
CEDACTerra | Miguel Rocha, arch. 30
It should also be noted that at this moment in Portugal we are already taking solid
steps in this field, with a view to the standardization of this material as well.
5.2. PRODUCT DATASHEETS
In relation to the properties required for CEB, the specifications refer to the
classification of products, dimensional, geometric, appearance, physical-chemical
or mechanical-hygrometric characteristics by means of required or recommended
values. These product standards that specify the requirements that must satisfy to
establish their suitability for use, are very common in the normative framework of
earth construction.
Fig. 16 – CEB building under construction.
The standards for CEB have a broader classification, greater geometric or
appearance characteristics than those referring to pieces of adobe. A very common
classification for CEB types is according to mechanical constraints, based on the
values of comprehension, case of Colombian, Spanish or African Regional
standards. They are usually solid blocks but are allowed crevices and perforations.
As an example, following is the reference of three CEB producers and respective
datasheets.
CEB IMPLEMENTATION REPORT - Vale das Lobas 31
- BIOTERRE (Spain, Cataluña)
- TERRABLOC (Switzerland)
CEB IMPLEMENTATION REPORT - Vale das Lobas 33
6. RESEARCH CENTERS AND
EARTH BUILDING ENTITIES
Since the beginning of the 80’s, great stress has been laid on research, academic
education and vocational training, in the field of production, architectural design
and building techniques, at every level. Technical data obtained on sites or from
researches have been put into practice. When properly managed, building
programs involving CEB have been a success worldwide.
Fig. 17 – Residential complex with attached CEB buildings.
The following entities are the two ones that develop the most significant knowledge
in earth construction, with worldwide projection.
- CRATerre-EAG – International Centre for Earth Construction (France).
Since 1979, CRAterre, the International Centre for Earthen architecture,
has worked towards the recognition of earth materials as a valid response
to the challenges linked to the protection of the environment, the
preservation of cultural diversity and the fight against poverty.
CEDACTerra | Miguel Rocha, arch. 34
In this perspective, CRAterre's three main objectives are centred on:
• Optimizing the use of local resources, human and natural
• Improving housing and living conditions
• Valorising and promoting cultural diversity.
With more than 35 years of involvement, CRAterre has assembled a
multidisciplinary team of researchers, professionals, lecturers and
trainers, working in collaboration with many partners, as a means to
establish creative links between research, on-the-field activities as well as
training, knowledge dissemination and sensitization activities.
- AVEI – Auroviile Earth Institute (India)
The Auroville Earth Institute (AVEI), previously known as the Auroville
Building Centre/Earth Unit, was founded by HUDCO, Government of India,
in 1989. The former building centre progressively evolved and took the
name of the Auroville Earth Institute in 2004.
AVEI is a non-profit organisation registered under the Foundation of
Auroville, which is an organisation of the Government of India.
In the intervening years, the Auroville Earth Institute has become one of
the world’s top centres for excellence in earthen architecture, working in
36 countries to promote and transfer knowledge in earth architecture. The
work of the Earth Institute has attempted to revive traditional skills and to
link ancestral and vernacular traditions of raw earth construction with the
modern technology of stabilised earth.
The activities of the institute include research and development of earthen
technologies, training and education, publication and dissemination, and
the following services offered within India and abroad: consultancy (with
priority given to NGO’s, governmental and international organisations),
architectural design and construction, heritage conservation, production
of materials, and quality control testing. Over the last 30 years, the
Auroville Earth Institute has become one of the world’s top centres for
excellence in earthen architecture, a leader in the research, development,
promotion and transfer of earth-based building technologies, mainly on
Compressed Stabilized Earth Blocks - CSEB.
CEB IMPLEMENTATION REPORT - Vale das Lobas 35
Fig. 18 – House built with CEB.
In Iberian Peninsula there are also some entities that are working in earth
construction area. In Spain there are several universities/ academic centres which
develop research and education on earth construction, including CEB. Between
them, in Spain:
- Universidad Politécnica de Madrid, E.T.S.I. - D.C.V.R., Madrid
- Universitat Politécnica de Catalunya, E.T.S.A.B, Barcelona
- Universidad de Valladolid, E.T.S.A.V. - Grupo Tierra, Valladolid
In Portugal, among others these are the main entities that develop some work in
the frame of earth construction:
- Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia,
Departamento de Engenharia Civil (contact: PhD Paulina Faria). Works on
academic education and research.
- Universidade do Minho, Departamento de Engenharia Civil. Works on academic
education, research and cooperation projects.
CEDACTerra | Miguel Rocha, arch. 36
- CEDACTerra – Centro para el Estudio y Desarrollo de la Arquitectura y
Construcción con Tierra (contact: arch. Miguel Rocha). Works on Consultancy,
Training, Design and Research.
Created in 2015 in Spain but with Iberian scope, CEDACTerra is a Centre for the
Study and Development of Earth Construction and Architecture.
It is run by arch. Miguel Rocha and ing. Rafael López, a team with more than 20
years of work experience in this area and in several countries.
The activity of the Centre goes around the techniques of raw earth construction
and its current use, whether in the field of bioclimatic architecture or conservation
and restoration of heritage buildings, offering its services to architects, civil
engineers and environmental technicians, as well as construction or real estate
development companies, development agents and public or private entities.
Its main objectives are:
- Put in value the use of raw earth in construction.
- Promote the use, development and modernization of traditional earth construction
techniques.
- Disseminate technical knowledge on the use of raw earth as a construction
material.
- Contribute to the development of more sustainable construction practices, based
on the use of raw earth.
Working in close collaboration with other appropriate technology organizations
(most of the above mentioned) and other eco-construction technicians and
experts, CEDACTerra provides technical and management expertise to all
organizations and individuals interested in the use of raw earth as building material.
CEDACTerra | Miguel Rocha, arch. 38
Fig. 20 – Three different houses, built with CEB: Morocco, Colombia and USA.
CEB IMPLEMENTATION REPORT - Vale das Lobas 41
ANNEX 1
COMPARISON OF BUILDING MATERIALS AT AUROVILLE (April 2009)
DETAILS WIRE CUT BRICKS COUNTRY FIRED
BRICKS
CEB 240 RAMMED EARTH
PR
OD
UC
T I
NFO
RM
ATIO
N
Brick size
(L, W, H, in cm)
22 x 10.5 x 7.2 22 x 10.5 x 6.5 24 x 24 x 9 (Wall cast in situ)
Volume of brick 1.66 Litres 1.50 Litres 5.18 Litres (Wall cast in situ)
Weight per unit 3.12 Kg = 1,876 Kg/m3 2.81 Kg = 1,871 Kg/m
3 10.00 Kg = 1,929 Kg/m
3 ~ 1,950 Kg/m
3
Stabilisation Fire Fire 5% 5%
Wastage of raw material 3 % 12 % 5 % 0 %
Units per m3
(raw material)
601 No 666 No. 193 No. No bricks
Pollution emission (CO2) 202.25 Kg / m3 441.12 Kg / m
3 110.11 Kg / m
3 16 Kg / m
3
Energy consumption 2,247.28 MJ / m3 4,501.25 MJ / m
3 1,112.36 MJ / m
3 110 MJ / m
2
Dry crushing strength 100 Kg / cm2 35 Kg / cm
2 50 Kg / cm
2 50 Kg / cm
2
Water absorption 9 to 11 % 10 to 14 % 9 to 12 % 8 to 11 %
WA
LLD
ETA
IL
Wall thickness 22 cm 22 cm 24 cm 24 cm
Mortar used 1 cement: 5 sand 1 cement: 5 sand 1 cement: 6 soil: 6 sand No mortar
Mortar Qty per m2 of wall 72.4 Litres 76 Litres 36.1 Litres No mortar
Units per m2 of wall
98
(with 1.5 cm mortar)
106
(with 1.5 cm mortar)
40
(with 1 cm mortar)
No bricks
Daily output per team 3.3 m2 = 320 bricks 4.6 m
2 = 490 bricks 3.8 m
2 = 150 blocks 8 m
2
CO
ST(R
s.)
Unit (Brick) on site 6.00 Rs./unit 2.80 Rs./unit 9.12 Rs./unit No bricks
Raw material per m3 * 3,716 per m
3 2,036 per m
3 1,847 per m
3 1,897 Per m
3
Mortar per m3 2,583 per m
3 2,583 per m
3 1,404 per m
3 No mortar
Finished wall per m3 4,893 per m
3 3,266 per m
3 2,763 per m
3 2,106 per m
3
Finished wall per m2 1,076 per m
2 719 per m
2 663 per m
2 505 per m
2
DA
TA
Sieved sand 525 per m3 Mason : 300 per day Labour male : 200 per day
Sieved soil 250 per m3 Helper : 200 per day Labour female : 130 per day
Cement (43 grades) 280 (50 Kg bag)
NO
TES
All costs are in Indian Rupees Value: Auroville, April 2009, 1 US $ = ~ 50 Rs.
* The cost of raw material include the wastage Wire cut bricks are also called kiln-fired or chamber bricks
All material costs includes the delivery on site Country fired bricks are also called village bricks
Block laying team = 1 mason, 1 helper, 1/2 labor male,
1/2 labor female