the basics of - vale das lobas€¦ · the product and the value and durability of buildings made...

CE

DA

CT

erra

CEB Dossier

VALE DAS LOBAS

Sobral Pichorro - Fornos de Algodres

MIGUEL ROCHA, arch.

CEDACTerra – Badajoz

March, 2017

CEDACTerra | Miguel Rocha, arch. 2

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


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.


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)


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).


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.


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.


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


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.


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.


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.


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.


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.


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!


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.


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.


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.


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


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.


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


15 to 30 kg/cm2

(Test after 3 days immersion)

30 to 40 kg/cm2

(Test after 24 hours immersion)

Dry bending strength


5 to 10 kg/cm2

10 to 20 kg/cm2

Dry shear strength


4 to 6 kg/cm2

4 to 6 kg/cm2

Water absorption


8 to 12 %


8 to 10 %


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 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.


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.


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


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.


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.


- BIOTERRE (Spain, Cataluña)

- TERRABLOC (Switzerland)


- SOLBLOC (Spain, Extremadura, Badajoz)


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.


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.


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 – 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.


Fig. 19 – CEB masonry.


Fig. 20 – Three different houses, built with CEB: Morocco, Colombia and USA.


ANNEXES


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

the basics of - vale das lobas€¦ · the product and the value and durability of buildings made...

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