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ALTERNATIVE BUILDING MATERIALS AND TECHNOLOGIES (Elective)

(Theory)

Course Code: 10CVA553 CIE Marks: 100

Hrs/Week: L:T:P : 3:0:0 SEE Marks: 100

Credits: 03 SEE Duration: 3 Hrs

Course Learning Objectives:

To study process that is environmentally responsible and resource-efficient throughout abuilding's life-cycle.

To study innovative solutions using state-of-the-art technologies and building materials. To study how to minimize environmental impact, facilities should use materials that have

been recycled and can generate a surplus of energy.

To study the behavior of structural masonry. To study the cost effective alternative building technology and design. To induce sustainable and inclusive technology.

UnitI 06 Hrs

Introduction: Energy in building materials, Environmental issues concerned to

building materials, Global warming and construction industry, Environmentalfriendly and cost effective building technologies, Requirements for building ofdifferent climatic regions, Traditional building methods and vernacular architecture .

UnitII 08 Hrs

Alternative Building Materials: Characteristics of building blocks for walls,Stones and Laterite blocks, Bricks and hollow clay blocks, Concrete blocks,Stabilized blocks: mud blocks, steam cured blocks, Fal-G Blocks.

UnitIII 08 Hrs

Alternative Building Technologies

Alternative Technology for wall construction, Types, Construction method,Masonry mortars, Types, Preparation, Properties, Ferro cement and ferroconcretebuilding, components, Materials and specifications, Properties, Constructionmethods, Applications, Alternative roofing systems-Concepts, Filler slabs,Composite beam panel roofs, Masonry vaults and domes.

UnitIV 08 Hrs

Structural Masonry: Compressive strength of masonry elements, Factors affectingcompressive strength, Strength of units, prisms / wallettes and walls, Effect of brickwork bond on strength, Bond strength of masonry: Flexure and shear, Elasticproperties of masonry materials and masonry

UnitV 06 Hrs

Cost Effective Building Design: Cost concepts in buildings, Cost savingtechniques in planning, design and construction Cost analysis: Case studies usingalternatives.


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Course outcomes:

After going through this course the student will be able to:

Student should be able to understand the environmental impact of conventionalbuilding materials and need for alternative materials . Students should be ableunderstand the need for sustainable and inclusive technology.

Should be able to design cost effective building planning, design andconstruction. Should be able to understand the behavior of structural masonrywhen subjected to various loadings on it.

Reference Books

1. K.S.Jagadish ,B.V.Venkataramareddy and K.S.Nanjunda Rao ., Alternative buildingMaterials and Technologies New Age International Publishers. 2009;ISBN 978-81-224-2037-1, Unit I-V

2. K.S .Jagadish, Building Alternatives for housing. Lecture notes on Alternative Building,

Dept of Civil Engg, Indian Institute of Science ,1997, Unit I-V

3. A.W.Hendry, Structural Masonry Macmillan Press, London, ISBN 9780333733097,Unit I-V

4. Sven Sahlin, Structural Masonry, Prentice Hall Inc., Englewood Cliffs, New Jersey,

ISBN 9780138539375, Unit I-V

5. IS: 1905; 1997 Indian standard Specification For Code Of Practice for Structural Use OfUnreinforced Masonry.

Scheme of Continuous Internal Evaluation:

CIE consists of Three Tests each for 45 marks (15 marks for Quiz + 30 marks for descriptive)out of which best of two will be considered. In addition there will be one seminar on newtopics / model presentation etc. for 10 marks.

Scheme of Semester End Examination:

The question paper consists of Part A and Part B. Part A will be for 20 marks covering thecomplete syllabus and is compulsory. Part B will be for 80 marks and shall consist of fivequestions (descriptive, analytical, problems or/and design) carrying 16 marks each. All fivefrom Part B will have internal choice and one of the two have to be answered compulsorily.


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INTRODUCTION

Although the Indian economy uses both commercial and non-commercial energy sources, the

share of these fuels in the primary energy supply has declined from over 70% in the early 50's to

a little over 30% as of today. The traditional fuels are gradually getting replaced by the

commercial fuels such as coal, lignite, petroleum products, natural gas and electricity Theominous outcry for energy crisis in various sectors like agriculture, transportation, land use and

built environment are widely recognized during the past couple of decades as a threat for the

future generation.

Building Industry is one of the fastest growing and a major energy consuming sector in India.

Needless to say, the buildings too form a link in the energy-spatial structure relationship. Apart

from the structural and functional efficiencies, building infrastructure also needs to emphasize on

the energy conservation issues. The energy in buildings may be looked from two different

perspectives. Firstly the energy that goes into the construction of the building using a variety of

materials. Secondly the energy that is required to create a comfortable environment within the

building during its lifetime. Quite a few studies regarding the energy consumed during the

maintenance of the building (heating, cooling and lighting) have been published. However the

assessment of the embodied energy in buildings is still in its nascent stage in India and requires

serious research.

Need for Energy Efficient BuildingsThe International Energy Report (IER) 1987 points out

Investment in energy conservation at a margin provides a better return than investment in

energy supply. The concept of green buildings is still at an emerging stage in India. The concept

of sustainable buildings and use of environmentally friendly construction materials like stones,

timber, thatch, mud etc have been practiced since ancient times. But the perception of people

about strong and durable buildings have changed with the advent and lavish use of the present

modern materials like steel, cement, aluminium, glass etc. A large amount of fuel energy gets

consumed.in producing such materials. These materials being industrial products further need to

be transported to large distances before getting consumed in the buildings thus making them

energy intensive. An estimate of the energy consumed in buildings using different permutations

of materials and techniques will facilitate their appropriate selection and reduce the embodied

energy consumption .

Some of the salient features to optimize the energy consumption in buildings are to:

1. Minimal disturbance to landscape and site conditions


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2. Use of renewable energy

3. Use of water recycling

4. Use of environmental friendly building materials

5. Effective controls for lighting and temperature for human comfort

Energy and Building Materials

Constructions consume a variety of building materials. Abundant raw materials are to be

transported from far off distances to the industry which requires further processing thus

consuming primary and commercial resources. The finished products from the industry further

need to be distributed to the local areas and construction sites which increase the pressure on the

commercial fuels like petrol/diesel etc.

The most common building materials used in construction activity today are cement, steel,

bricks, stones, glass, aluminium, timber, etc. The estimates of the energy consumed in the

manufacture/extraction of a few major building materials chosen from various sources have been

discussed below.

i) Cement

The principal methods for the manufacture of the Portland cement are

1) Wet process,

2) Dry process,

3) Semi dry process.

The dry process is preferred on account of very significant fuel economy. The dry process is

adopted in most of the cement industries. The heat energy required per Kg of the clinker in dry

process is

1.572.35 MJ/Kg while in wet process it is about 2.6 4.2 (MJ/Kg). The highest value of 4.2

MJ/Kg has

ii) Steel

The transportation of various raw materials like Iron ore lumps, sinters and pellets, coke and

fluxes such as limestone, dolomite and the various processes like Melting, Refining, Casting,

Rolling makes steel as an highly energy intensive material. The total energy in steel is estimated

to be 36MJ/Kg, including transportation.

iii) Bricks

The manual production of the bricks involves mainly four operations namely, Soil preparation,

Moulding, Drying and Firing. The main process in which energy is consumed is firing of bricks.


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The amount of total coal required is about 18 tonnes to 22 tonnes depending upon the weather

condition, quality of coal, etc. A tonne of coal gives about 12.3MJ to 13.3MJ depending upon

quality of the coal generally transported from far off distances. The energy required to produce

each brick inclusive of transportation comes to about 5MJ per brick.

iv) GlassRaw materials used in Manufacture of glass are 1) Glass sand 2) Soda ash 3) Salt cake 4) Lime

stone 5) Lead oxides, pearl ash, boric acid, etc. The various processes used are 1) Melting. 2)

Shaping or Forming 3) Annealing 4) Finishing The embodied energy of glass is some what high

due to melting process comes out

to be 15.9 MJ/ Kg.

Embodied Energyis the sum of all the energy required to produce goods or services, considered

as if that energy was incorporated or 'embodied' in the product itself. The concept can be useful

in determining the effectiveness of energy-producing or energy-saving devices (does the device

produce or save more energy that it took to make it?, of buildings, and, because energy-inputs

usually entail greenhouse emissions, in deciding whether a product contributes to or

mitigatesglobal warming.

Embodied energy is an accounting method which aims to find the sum total of the energy

necessary for an entire product life-cycle. Determining what constitutes this life-cycle includes

assessing the relevance and extent of energy into raw material extraction, transport, manufacture,

assembly, installation, dis-assembly, deconstruction and/or decomposition as well as human and

secondary resources. Different methodologies produce different understandings of the scale and

scope of application and the type of energy embodied.

ENERGY EFFICIENT BUILDING MATERIALS AND TECHNOLOGIES

Considerable amount of energy is spent in the manufacturing processes and transportation of

various building materials. Conservation of energy becomes important in the context of limiting

of green house gases emission in to the atmosphere and reducing costs of materials. Some issues

pertaining to embodied energy in buildings particularly in the Indian context have been

examined. Analysis of energy consumption in the production of basic building materials and

different types of materials used for construction along with energy spent in transportation of

various building materials has been made. Energy in different types of alternative roofing

systems has been discussed and compared with the energy of conventional R. C. slab roof. Total
http://en.wikipedia.org/wiki/Global_warminghttp://en.wikipedia.org/wiki/Global_warming


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embodied energy of a multi-storeyed building, a load bearing brickwork building and a soil-

cement block building using alternative building materials has been compared. It has been shown

that total embodied energy of load bearing masonry buildings can be reduced by 50% when

energy efficient/alternative building materials are used.

Cost Effective Environment Friendly Construction Technologies

Housing, next to food and clothing is the most important need of a human being. The house

reflects his/her socio-economic status in society. For most families, housing is perhaps a major

goal of family saving effort. So it must be durable, as it is an outcome of a long drawn process of

savings and aspirations.

Housing is a bundle of goods and services. It is not the product of uni-sectoral efforts. Housing

production includes a multitude of tasks like land acquisition, development, laying infrastructure,site planning and architectural design on pre-conceived concepts of affordable densities, to

provide for shelter, social and physical infrastructure, project finance and finally construction

and delivery of the same.

It is within this context that a need was felt to look at ways of optimizing shelter cost. The usual

practice involved in this area till the recent past has been to:

1. Reduce area of the house to the minimum possible level2. Reduce the finishing specification of flooring, external and internal walls, fittings etc.In last two to three decades, cost effective appropriate technologies have cross the borders of

laboratory and research organizations and have reached real construction sites. Many

experimental and demonstrative projects have been constructed across the country proving the

strength and feasibility of these technologies.

A number of cost effective appropriate materials and technologies have been developed,

standardized and are being used in the field with success over the years. Many of them have even

proved themselves in the test of time. BIS has also included many of these technologies under

their umbrella and are working towards covering the remaining so that minimum standardization

is achieved and a standard specification for the same is evolved.


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Some of the Cost effective appropriate Technologies are described in the table below

BuildingComponent Alternative Systems

Foundations

Random rubble masonry in mud/cement mortar placed inexcavation over thick sand bed. Rubble pointing above groundlevel in stabilized cement mortar.

Use of lean cement concrete mix 1:8:16 for base with brickmasonry in 1:6 cement mortar footings.

Use of lean cement concrete mix as above for base and overburned bricks masonry in cement lime mortar (1:2:12) footings.

Arch foundations in place of spread foundations

Walls

Brick work in 1:6 cement mortar using bricks from black cottonand inferior soil stabilized with fly-ash.

Rat-trap bond brick work in 1:2:12 cement lime mortar/1:1.5:3cement sand mortar.

Hollow concrete block masonry in cement mortar. Compressed mud blocks masonry in mud mortar. Stabilized mud blocks masonry (4% cement or lime) in stabilized

mud mortar. Sand lime brick walls in 1:6 cement mortar. FAL-G sand block with 1:6 cement mortar.

Roofs

Domes and vaults in brick or stabilized mud block withappropriate mortar.

Upgraded thatch roof on appropriate frame work. Pre-cast RCC L panel Precast RCC cored units in M15 concrete. Precast RCC channel units in M15 concrete Precast Waffle units in M15 concrete Burnt clay tube roofing in vault form.

Roof/ intermediate

slab

Filler slabs Partly precast RCC planks and joist in M15 concrete. Partly precast RCC joist and brick panels Partly precast RCC in hollow concrete blocks Thin RCC ribbed slabs Ferrocement channels Brick funicular shell on edge beam Bamboo reinforced concrete


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Brick funicular shells with RCC edge beams Brick jack arched over RCC joist Precast RCC cored units in M15 concrete. Precast RCC channel units in M15 concrete

Spanning elements

for openings

Brick arches : Flat, semi circular and segmented Precast thin lintel and lintel cum chajja Brick arch with sand stone chajja Ferro cement chajjas

Door cum window

frames

Precast RCC frames with wood insert Resin bonded saw dust frame Polyvinyl chloride frame Fiber reinforced plastic frame

Door panels

Plantation timber styles with particle board inserts. Medium density fiber board doors. Cement bonded particle board Plantation timber style with rice husk board inserts Red mud polymer panel doors. Ferrocement doors Polyvinyl chloride doors panels.

Generic Characteristics

Building blocks have generic characteristics as follows:

A building block is a package of functionality defined to meet the business needs acrossan organization.

A building block has published interfaces to access the functionality. A building block may interoperate with other, inter-dependent, building blocks. A good building block has the following characteristics:


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o It considers implementation and usage, and evolves to exploit technology andstandards.

o It may be assembled from other building blocks.o It may be a subassembly of other building blocks.o

Ideally a building block is re-usable and replaceable, and well. specified. A building block may have multiple implementations but with different inter-dependent

building blocks.

A building block is therefore simply a package of functionality defined to meet business needs.

The way in which functionality, products, and custom developments are assembled into building

blocks will vary widely between individual architectures. Every organization must decide for

itself what arrangement of building blocks works best for it. A good choice of building blocks

can lead to improvements in legacy system integration, interoperability, and flexibility in the

creation of new systems and applications.

Systems are built up from collections of building blocks, so most building blocks have to

interoperate with other building blocks. Wherever that is true, it is important that the interfaces to

a building block are published and reasonably stable.

Building blocks can be defined at various levels of detail, depending on what stage of

architecture development has been reached.

For instance, at an early stage, a building block can simply consist of a grouping of functionality

such as a customer database and some retrieval tools. Building blocks at this functional level of

definition are described in TOGAF as Architecture Building Blocks (ABBs). Later on, real

products or specific custom developments replace these simple definitions of functionality, and

the building blocks are then described as Solution Building Blocks (SBBs).

More detail on each of these aspects of building blocks is given below.

Architecture Building Blocks

Architecture Building Blocks (ABBs) relate to the Architecture Continuum (The Architecture

Continuum), and are defined or selected as a result of the application of the ADM.
http://pubs.opengroup.org/architecture/togaf8-doc/arch/chap18.html#tag_19_01http://pubs.opengroup.org/architecture/togaf8-doc/arch/chap18.html#tag_19_01http://pubs.opengroup.org/architecture/togaf8-doc/arch/chap18.html#tag_19_01http://pubs.opengroup.org/architecture/togaf8-doc/arch/chap18.html#tag_19_01


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Characteristics

ABBs:

Define what functionality will be implemented Capture business and technical requirements Are technology aware Direct and guide the development of SBBs

Specification Content

ABB specifications include the following as a minimum:

Fundamental functionality and attributes: semantic, unambiguous, including securitycapability and manageability

Interfaces: chosen set, supplied (APIs, data formats, protocols, hardware interfaces,standards)

Dependent building blocks with required functionality and named user interfaces Map to business/organizational entities and policies

Solution Building Blocks

Solution Building Blocks (SBBs) relate to the Solutions Continuum (The Solutions Continuum),

and may be either procured or developed.

Characteristics

SBBs:

Define what products and components will implement the functionality Define the implementation Fulfil business requirements Are product or vendor-aware

Specification Content

SBB specifications include the following as a minimum:
http://pubs.opengroup.org/architecture/togaf8-doc/arch/chap18.html#tag_19_02http://pubs.opengroup.org/architecture/togaf8-doc/arch/chap18.html#tag_19_02http://pubs.opengroup.org/architecture/togaf8-doc/arch/chap18.html#tag_19_02http://pubs.opengroup.org/architecture/togaf8-doc/arch/chap18.html#tag_19_02


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Specific functionality and attributes Interfaces; the implemented set Required SBBs used with required functionality and names of the interfaces used Mapping from the SBBs to the IT topology and operational policies

Specifications of attributes shared across the environment (not to be confused withfunctionality) such as security, manageability, localizability, scalability

Performance, configurability Design drivers and constraints, including the physical architecture Relationships between SBBs and ABBs

Building Blocks and the ADM

Basic Principles

This section focuses on the use of building blocks in the ADM. General considerations and

characteristics of building blocks are described inIntroduction to Building Blocks .

Building Blocks in Architecture Design

An architecture is a set of building blocks depicted in an architectural model, and a specification

of how those building blocks are connected to meet the overall requirements of an information

system.The various building blocks in an architecture specify the services required in an

enterprise-specific system.

There are some general principles underlying the use of building blocks in the design of specific

architectures:

An architecture need only contain building blocks to implement those services that itrequires.

Building blocks may implement one, more than one, or only part of a service identified inthe architecture framework.

Building blocks should conform to standards relevant to the services they implement.
http://pubs.opengroup.org/architecture/togaf8-doc/arch/chap32.html#tag_33_02http://pubs.opengroup.org/architecture/togaf8-doc/arch/chap32.html#tag_33_02


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LATERITES

Laterites aresoil types rich iniron andaluminium,formed in hot and wet tropical areas. Nearly

all laterites are rusty-red because ofiron oxides. They develop by intensive and long-

astingweathering of the underlyingparent rock.Tropical weathering (laterization) is a prolonged

process of chemical weathering which produces a wide variety in the thickness, grade, chemistry

and ore mineralogy of the resulting soils. The majority of the land areas with laterites was or is

between the tropics ofCancer andCapricorn.

Historically, laterite was cut into brick-like shapes and used in monument building. After 1000

CE construction atAngkor Wat and other southeast Asian sites changed to rectangular temple

enclosures made of laterite, brick and stone. Since the mid-1970s trial sections ofbituminous-

surfaced low-volume roads have used laterite in place of stone as a base course. Thick laterite

layers are porous and slightly permeable, so the layers can function asaquifers in rural areas.

Locally available laterites are used in an acid solution, followed by precipitation to

removephosphorus and heavy metals at sewage treatment facilities.

Laterites are a source of aluminiumore; the ore exists largely inclay minerals and

thehydroxides,gibbsite,boehmite,anddiaspore,which resembles the composition ofbauxite.In

Northern Ireland they once provided a major source of iron and aluminium ores. Laterite ores

also were the early major source ofnickel.

Definition and physical description

Laterite inSnTy,Hanoi,Vietnam.

Francis Buchanan-Hamilton first described and named a laterite formation in southernIndiain

1807.He named it laterite from the Latin word later, which means a brick; this rock can easily be

cut into brick-shaped blocks for building.The word laterite has been used for

variablycemented,sesquioxide-richsoil horizons.A sesquioxide is anoxide with three atoms of
http://en.wikipedia.org/wiki/Soilhttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Aluminiumhttp://en.wikipedia.org/wiki/Iron_oxidehttp://en.wikipedia.org/wiki/Weatheringhttp://en.wikipedia.org/wiki/Parent_rockhttp://en.wikipedia.org/wiki/Tropic_of_Cancerhttp://en.wikipedia.org/wiki/Tropic_of_Capricornhttp://en.wikipedia.org/wiki/Angkor_Wathttp://en.wikipedia.org/wiki/Bitumenhttp://en.wikipedia.org/wiki/Aquiferhttp://en.wikipedia.org/wiki/Sewage_treatment#Phosphorus_removalhttp://en.wikipedia.org/wiki/Orehttp://en.wikipedia.org/wiki/Clay_mineralhttp://en.wikipedia.org/wiki/Hydroxidehttp://en.wikipedia.org/wiki/Gibbsitehttp://en.wikipedia.org/wiki/Boehmitehttp://en.wikipedia.org/wiki/Diasporehttp://en.wikipedia.org/wiki/Bauxitehttp://en.wikipedia.org/wiki/Nickelhttp://en.wikipedia.org/wiki/S%C6%A1n_T%C3%A2yhttp://en.wikipedia.org/wiki/S%C6%A1n_T%C3%A2yhttp://en.wikipedia.org/wiki/S%C6%A1n_T%C3%A2yhttp://en.wikipedia.org/wiki/Hanoihttp://en.wikipedia.org/wiki/Vietnamhttp://en.wikipedia.org/wiki/Francis_Buchanan-Hamiltonhttp://en.wikipedia.org/wiki/Indiahttp://en.wikipedia.org/wiki/Cementation_(geology)http://en.wikipedia.org/wiki/Sesquioxidehttp://en.wikipedia.org/wiki/Soil_horizonhttp://en.wikipedia.org/wiki/Oxidehttp://en.wikipedia.org/wiki/File:Da_ong_Laterite.JPGhttp://en.wikipedia.org/wiki/Oxidehttp://en.wikipedia.org/wiki/Soil_horizonhttp://en.wikipedia.org/wiki/Sesquioxidehttp://en.wikipedia.org/wiki/Cementation_(geology)http://en.wikipedia.org/wiki/Indiahttp://en.wikipedia.org/wiki/Francis_Buchanan-Hamiltonhttp://en.wikipedia.org/wiki/Vietnamhttp://en.wikipedia.org/wiki/Hanoihttp://en.wikipedia.org/wiki/S%C6%A1n_T%C3%A2yhttp://en.wikipedia.org/wiki/Nickelhttp://en.wikipedia.org/wiki/Bauxitehttp://en.wikipedia.org/wiki/Diasporehttp://en.wikipedia.org/wiki/Boehmitehttp://en.wikipedia.org/wiki/Gibbsitehttp://en.wikipedia.org/wiki/Hydroxidehttp://en.wikipedia.org/wiki/Clay_mineralhttp://en.wikipedia.org/wiki/Orehttp://en.wikipedia.org/wiki/Sewage_treatment#Phosphorus_removalhttp://en.wikipedia.org/wiki/Aquiferhttp://en.wikipedia.org/wiki/Bitumenhttp://en.wikipedia.org/wiki/Angkor_Wathttp://en.wikipedia.org/wiki/Tropic_of_Capricornhttp://en.wikipedia.org/wiki/Tropic_of_Cancerhttp://en.wikipedia.org/wiki/Parent_rockhttp://en.wikipedia.org/wiki/Weatheringhttp://en.wikipedia.org/wiki/Iron_oxidehttp://en.wikipedia.org/wiki/Aluminiumhttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Soil


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oxygen and two metal atoms. It has also been used for any reddish soil at or near the Earth's

surface.

Laterite covers are thick in the stable areas of theWestern Ethiopian Shield,on cratons of the

South American Plate, and on theAustralian Shield.InMadhya Pradesh,India, the laterite which

caps the plateau is 30 m (100 ft) thick.Laterites can be either soft and easily broken into smaller

pieces, or firm and physically resistant.Basement rocks are buried under the thick weathered

layer and rarely exposed.Lateritic soils form the uppermost part of the laterite cover.

Formation

Laterite is often located under residual soils.

A represents soil; B represents laterite, a regolith; C represents saprolite, a less-weathered

regolith; D represents bedrock

Tropical weathering (laterization) is a prolonged process of chemical weathering which produces

a wide variety in the thickness, grade, chemistry and ore mineralogy of the resulting soils. The
http://en.wikipedia.org/wiki/Western_Ethiopian_Shieldhttp://en.wikipedia.org/wiki/Australian_Shieldhttp://en.wikipedia.org/wiki/Madhya_Pradeshhttp://en.wikipedia.org/wiki/Basement_(geology)http://en.wikipedia.org/wiki/File:Estructura-suelo.jpghttp://en.wikipedia.org/wiki/File:Laterite-saprolite_cross_section.PNGhttp://en.wikipedia.org/wiki/File:Estructura-suelo.jpghttp://en.wikipedia.org/wiki/File:Laterite-saprolite_cross_section.PNGhttp://en.wikipedia.org/wiki/Basement_(geology)http://en.wikipedia.org/wiki/Madhya_Pradeshhttp://en.wikipedia.org/wiki/Australian_Shieldhttp://en.wikipedia.org/wiki/Western_Ethiopian_Shield


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laterites occur in zones of the earth which experienced prolonged tropical weathering

ofultramafic rockscontaining the ferro-magnesian mineralsolivine,pyroxene,andamphibole.

Locations

Yves Tardy, from the French Institut National Polytechnique de Toulouse and the Centre

National de la RechercheScientifique, calculated that laterites cover about one-third of the

Earth's continental land area.Lateritic soils are thesubsoils of the equatorial forests, of

thesavannas of the humid tropical regions, and of theSaheliansteppes.They cover most of the

land area between the tropics of Cancer and Capricorn; areas not covered within these latitudes

include the extreme western portion of South America, the southwestern portion of Africa, the

desert regions of north-central Africa, the Arabian peninsula and the interior of Australia.

Some of the oldest and most highly deformed ultramafic rocks which underwent laterization are

found in the complexPrecambrianshields in Brazil and AustraliaSmaller highly

deformedAlpine-type intrusives have formed laterite profiles in Guatemala, Columbia, Central

Europe, India and Burma.Large thrust sheets ofMesozoic to Tertiary 251- to 65-million-year-

oldisland arcs andcontinental collision zones underwent laterization in New Caledonia, Cuba,

Indonesia and the Philippines.Laterites reflect past weathering conditions; laterites which are

found in present-day non-tropical areas are products of formergeological epochs,when that area

was near the equator. Present-day laterite occurring outside the humid tropics are considered to

be indicators of climatic change, continental drift or a combination of both.

Uses Building blocks
http://en.wikipedia.org/wiki/Ultramafic_rockhttp://en.wikipedia.org/wiki/Olivinehttp://en.wikipedia.org/wiki/Pyroxenehttp://en.wikipedia.org/wiki/Amphibolehttp://en.wikipedia.org/wiki/Subsoilhttp://en.wikipedia.org/wiki/Savannahttp://en.wikipedia.org/wiki/Sahelhttp://en.wikipedia.org/wiki/Steppeshttp://en.wikipedia.org/wiki/Precambrianhttp://en.wikipedia.org/wiki/Alpine_orogenyhttp://en.wikipedia.org/wiki/Mesozoichttp://en.wikipedia.org/wiki/Island_archttp://en.wikipedia.org/wiki/Continental_collisionhttp://en.wikipedia.org/wiki/Supercontinentshttp://en.wikipedia.org/wiki/File:Laterite_quarry,_Angadipuram,_India._C_004.jpghttp://en.wikipedia.org/wiki/Supercontinentshttp://en.wikipedia.org/wiki/Continental_collisionhttp://en.wikipedia.org/wiki/Island_archttp://en.wikipedia.org/wiki/Mesozoichttp://en.wikipedia.org/wiki/Alpine_orogenyhttp://en.wikipedia.org/wiki/Precambrianhttp://en.wikipedia.org/wiki/Steppeshttp://en.wikipedia.org/wiki/Sahelhttp://en.wikipedia.org/wiki/Savannahttp://en.wikipedia.org/wiki/Subsoilhttp://en.wikipedia.org/wiki/Amphibolehttp://en.wikipedia.org/wiki/Pyroxenehttp://en.wikipedia.org/wiki/Olivinehttp://en.wikipedia.org/wiki/Ultramafic_rock


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When moist, laterites can be easily cut with a spade into regular-sized blocks.Laterite is mined

while it is below the water table, so it is wet and soft. Upon exposure to air it gradually hardens

as the moisture between the flat clay particles evaporates and the larger iron salts lock into a

rigidlattice structureand become resistant to atmospheric conditions.The art of quarrying laterite

material intomasonry is suspected to have been introduced from the Indian subcontinent.

After 1000 CE Angkorian construction changed from circular or irregular earthen walls to

rectangular temple enclosures of laterite, brick and stone structures.Geographic surveys show

areas which have laterite stone alignments which may be foundations of temple sites that have

not survived.The Khmer people constructed the Angkor monuments which are widely

distributed in Cambodia and Thailand between the 9th and 13th centuries.The stone materials

used were sandstone and laterite; brick had been used in monuments constructed in the 9th and

10th centuries.Two types of laterite can be identified; both types consist of the minerals

kaolinite, quartz, hematite and goethite.Differences in the amounts of minor elements arsenic,

antimony, vanadium and strontium were measured between the two laterites.

Angkor Wat located in present-day Cambodia is the largest religious structure built

bySuryavarman II, who ruled theKhmer Empire from 1112 to 1152.It is a World Heritage

site.[16]:39The sandstone used for the building of Angkor Wat is Mesozoic sandstone quarried in

the Phnom Kulen Mountains, about 40 km (25 mi) away from the temple. The foundations and

internal parts of the temple contain laterite blocks behind the sandstone surface. The masonry

was laid without joint mortar.

Road building

Laterite road near Kounkane, Upper Casamance, Senegal
http://en.wikipedia.org/wiki/Crystal_structure#Lattice_systemshttp://en.wikipedia.org/wiki/Masonryhttp://en.wikipedia.org/wiki/Angkor_Wathttp://en.wikipedia.org/wiki/Suryavarman_IIhttp://en.wikipedia.org/wiki/Khmer_Empirehttp://en.wikipedia.org/wiki/Laterite#cite_note-waragai-15http://en.wikipedia.org/wiki/Laterite#cite_note-waragai-15http://en.wikipedia.org/wiki/File:Laterite-Casamance.jpghttp://en.wikipedia.org/wiki/File:Laterite-Casamance.jpghttp://en.wikipedia.org/wiki/File:Laterite-Casamance.jpghttp://en.wikipedia.org/wiki/File:Laterite-Casamance.jpghttp://en.wikipedia.org/wiki/Laterite#cite_note-waragai-15http://en.wikipedia.org/wiki/Khmer_Empirehttp://en.wikipedia.org/wiki/Suryavarman_IIhttp://en.wikipedia.org/wiki/Angkor_Wathttp://en.wikipedia.org/wiki/Masonryhttp://en.wikipedia.org/wiki/Crystal_structure#Lattice_systems


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The French surfaced roads in the Cambodia, Thailand and Viet Nam area with crushed laterite,

stone or gravel. Kenya, during the mid-1970s, and Malawi, during the mid-1980s, constructed

trial sections of bituminous-surfaced low-volume roads using laterite in place of stone as a base

course. The laterite did not conform with any accepted specifications but performed equally well

when compared with adjoining sections of road using stone or other stabilized material as abase. In 1984 US$40,000 per 1 km (0.62 mi) was saved in Malawi by using laterite in this way.

Water supply

Bedrock in tropical zones is often granite, gneiss, schist or sandstone; the thick laterite layer is

porous and slightly permeable so the layer can function as an aquifer in rural areas. One example

is the Southwestern Laterite (Cabook) Aquifer in Sri Lanka.This aquifer is on the southwest

border of Sri Lanka, with the narrow Shallow Aquifers on Coastal Sands between it and the

ocean.It has considerable water-holding capacity, depending on the depth of the formation.The

aquifer in this laterite recharges rapidly with the rains of AprilMay which follow the dry season

of FebruaryMarch, and continues to fill with themonsoon rains.The water table recedes slowly

and is recharged several times during the rest of the year.In some high-density suburban areas the

water table could recede to 15 m (50 ft) below ground level during a prolonged dry period of

more than 65 days.The Cabook Aquifer laterites support relatively shallow aquifers that are

accessible to dug wells.

Waste water treatment

In Northern Ireland phosphorus enrichment of lakes due to agriculture is a significant

problem. Locally available lateritea low-grade bauxite rich in iron and aluminium is used in

acid solution, followed by precipitation to remove phosphorus and heavy metals at several

sewage treatment facilities.Calcium-, iron- and aluminium-rich solid media are recommended for

phosphorus removal. A study, using both laboratory tests and pilot-scale constructed wetlands,

reports the effectiveness of granular laterite in removing phosphorus and heavy metals from

landfillleachate.Initial laboratory studies show that laterite is capable of 99% removal of

phosphorus from solution. A pilot-scale experimental facility containing laterite achieved 96%

removal of phosphorus. This removal is greater than reported in other systems. Initial removals

of aluminium and iron by pilot-scale facilities have been up to 85% and 98%

respectively.Percolating columns of laterite removed enoughcadmium,chromium andlead to

undetectable concentrations. There is a possible application of this low-cost, low-technology,

visually unobtrusive, efficient system for rural areas with dispersed point sources of pollution.
http://en.wikipedia.org/wiki/Monsoonhttp://en.wikipedia.org/wiki/Leachatehttp://en.wikipedia.org/wiki/Cadmiumhttp://en.wikipedia.org/wiki/Chromiumhttp://en.wikipedia.org/wiki/Leadhttp://en.wikipedia.org/wiki/Leadhttp://en.wikipedia.org/wiki/Chromiumhttp://en.wikipedia.org/wiki/Cadmiumhttp://en.wikipedia.org/wiki/Leachatehttp://en.wikipedia.org/wiki/Monsoon


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Fal G Blocks

Overview of Technology

The FaL-G technology works with the strength of fly ash, lime and gypsum chemistry. The slow

chemistry of fly ash and lime is maneuvered by tapping ettringite phase to its threshold limitsthrough sufficient input of gypsum. Therefore, FaL-G does not require heavy duty-press or 2

autoclave, which are otherwise required in case of only fly ash and lime. The FaL-G process

completely eliminates the thermal treatment (except open air drying) and does not require

combustion of any fossil fuel. The ingredients of the FaL-G bricks and blocks, fly ash, lime, and

gypsum, are well-known minerals that are widely used in industries. All these materials are

available in form of wastes and bi-products from industrial activities and are available in

adequate quantities in the areas, where the project activities are located. In certain cases, where

by-product lime is not available in adequate quantity, ordinary Portland cement (OPC) is used as

the source of lime, producing the same quality of bricks and blocks. The technology is proved to

be environmentally safe and sound.

The schematic FaL-G process is provided in the following diagram.

Storage of raw materials

Fly ash : In open yard, duly wetted and covered by Plastic sheet.

Stone dust: In open yard, duly wetted and covered by Plastic sheet

Lime sludgeDumped in open yard or stored in packets

OPC: In bags, stored in godowns.

Gypsum: In bags, stored in godowns.

Wet mixing in Roller Mixer

Raw materials are kneaded under rollers for

achieving homogenous mortar

Casting of bricks/blocks

The homogenised mortar taken out of roller mixer is put

into the mould boxes. Depending on the type of machine,

the product is compacted under vibration/ vibropress/

hydraulic compression etc.

Drying & Curing


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The green bricks are dried up under sun from 24 to 48 hours,

depending whether lime route or cement route; the dried up bricks

are stacked and subjected for water spray curing once or twice a

day, for 7-21 days, depending on ambience.

DESPATCH TO THE MARKET

Fly ash Lime/OPC Gypsum Stone Dust

IMPACT IDENTIFICATION & ASSESSMENT

Identification of Environmental and Social Issues&Identification of Environmental issues

The project promotes an eco-friendly technology for production of alternative building materials.

By avoiding use of fossil fuel in the production process of the alternative building material, the

project contributes to conservation of energy and fossil fuel (coal). By displacing burnt claybricks in the walling materials market, the project contributes to reduction of environmental

degradation such as land degradation and air pollution caused by the clay brick industry.

Furthermore since the alternative building material is manufactured using industrial wastes and

bi-products as raw materials, the environmental impacts associated with improper disposal of

such industrial wastes are mitigated by the project. The project is therefore considered

environmentally benign. On social front, the project creates business opportunities for the small

and micro enterprises. In contrast to the seasonal production-operations in the clay brick

industry, FaL-G plants have the advantage of continuous year-wide operation, and hence provide

yearlong employment opportunity for the skilled artisans and create self-help livelihood

opportunities for the illiterate poor.There are however certain environmental and social issues

pertaining to the operation of the FaLG plants, especially those pertaining to the handling of

different materials and the occupational health and safety issues of the workers.

These issues have been identified in the following Mixing, Moulding & Compression.

Degradation of ambient air quality due to operation of diesel engine

Accidental hazards of workers due to working near mechanical equipments

Direct exposure of workers to exhausts from diesel engines


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Identification of Social Issues

The FaL-G technology offers several positive social benefits. These include employment

opportunity for workers, longer employment in a year compared to seasonal employment in

conventional brick plants, business opportunity or the small entrepreneurs. Some of the

incidental adverse impacts of the project include the possibility of employment of child andbonded labour, possibility of wage disparity between male and female workers. Though there is

not even a single case of HIV reported so far out of over 20000 workers working in over 1800

plants, risk of HIV/AIDS among the migrant workers need to be guarded. These issues have

been assessed in the subsequent sections.

Assessment of Environmental and Social Impacts

Generally, the environmental impacts can be categorized as either primary or secondary. Primary

impacts are those, which are attributed directly by the project, and secondary impacts are those,

which are indirectly induced and typically include the associated investment and changed

patterns of social and economic activities by the proposed actions. In this chapter only direct

impacts have been considered. The environmental impacts may include all those that are

beneficial or adverse, short or long term (acute or chronic), temporary or permanent, direct or

indirect, and local or regional. The adverse impacts may include all those leading to, harm to

living resources, damage to human health, hindrance to other activities, impairment of quality for

use, reduction of amenities, damage to physical structures, etc. For each identified potential

environmental impact, the associated environmental risk is assessed based on its nature, duration,

likelihood, significance and level.

Environmental Aspects and Potential Impacts

Land Use

Land requirement for FaL-G unit is varied from 0.5 to 1.0 hectare and confined to one place

mainly, unlike red brick unit. As such FaL-G units could be operational on wide type of land,

preferably flat. It should be ideal if FaL-G unit is located at notified industrial areas.

Raw materials

The raw materials used for manufacturing of bricks by using FaL-G technology are: Fly ash

produced as waste material from coal based thermal power plant; Lime Produced as waste

material from paper and other industries; Gypsum produced as by product from fertilizers

and aluminium plant; Sand sourced from riverbed; Stone dustproduced as rejects from

stone crushers; and OPCproduct from cement plant, which is used as a substitute of lime. It

is evident that about 85100% of the total raw materials are either waste material or byproduct,


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barring sand. Only OPC is used in case of non-availability/non-suitability of Lime. Hence, there

is lot of saving of natural resources like fertile soil and coal, if compared with red bricks activity.

Cement stabilized mud block

Overview of technology and block productionEarth has widely been used as a material for building with significant variations resulting from

topography and climatic differences. The common methods used for earth construction are cob,

wattle and daub, rammed earth, and adobe. Earth based construction has several limitations such

as water penetration, erosion at lower levels due to splashing of water and attack by termites.

Cement Stabilized Soil Blocks (CSSB) overcomes these limitations by an increase in block

density through compaction using a mechanical press. The strength obtained at the optimum

moisture content is stabilized by using an additive such as cement or lime in the mixture. The

water content required in the soil is low for compaction as compared to puddle clay required for

mud bricks, which ensures much greater dimensional stability.

CSSBs are dense solid blocks produced by compacting a mixture of soil, sand, stabilizer(cement/lime) and water using a machine. The blocks are cured for 21 days before being used for

wall construction. Typical block sizes of 305 143 100 mm and 230 190 100 mm are

produced using a soil compaction press (Reddy, 2004). The compressive strength of the block

greatly depends upon the soil composition, density of the block and percentage of stabilizer

(cement/lime). Therefore, careful consideration of clay-sand percentages in soil is required to

ensure adequate block strength. Cement content of 6-7% cement and clay content of about 15%

can yield blocks having wet compressive strength of 3.0 MPa, sufficient for two storied buildings

(Jagadish et al, 2007). Higher strength for the block can be obtained by increasing the quantity of

stabilizer.

CSSBs are economical and easy to manufacture locally and have been produced in certain areas

using soil excavated at the construction site. Their use in India has been more popular for small

scale construction projects with blocks being produced using a manual press. Although

motorized hydraulic presses are available, their use has been limited in India. Since CSSBs are

produced at site and there is no production unit in India, information on production was obtained

from literature and discussions with practitioners of this technology. CSSBs have been used

predominantly in small scale residential construction and in regions such as Karnataka,

Pondicherry, Gujarat, Haryana and West Bengal, where research and dissemination activities

have been concentrated. Although this form of construction is economical, the production of

blocks requires technical expertise to assess soil characteristics and the appropriate mix ofcement. This has been a barrier for its adoption. The perceptions of this material having a very

small quantity of cement and thus not having adequate strength have also been impediments.

The process of producing CSSBs first involves sieving soil and mixing sand or quarry dust to

achieve the correct clay-sand percentages. Cement and/or lime is then added and mixed with

water to obtain optimum moisture content. The correct amount of soil is weighed and compacted

in a press. The block is then stacked and cured before being used for construction. A block of


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305 mm x 143 mm x 100 mm requires 1.52 kg (17%) of clay, 0.54 kg (6%) of cement, 5.81 kg

(65%) of sand and 1.07 kg (12%) of silt.

Where clay and sand are sourced from other locations and not from excavated earth at site, they

are transported to the site from an average distance of about 40 km. The quantities of raw

materials mixed are carefully controlled and the production of the blocks is supervised to ensure

uniform compressive strengths. The total water used in the mix and for curing the blocks was

estimated to be 6.0 liters. Since the mixing and moulding processes are manual, electricity or fuel

is not used in the production process. About 350 blocks can be produced in a day employing six

persons. The blocks are typically produced and used at the construction site and have no

transportation requirement for the finished blocks.

Fired bricks

Overview

Fired clay bricks are one of the most important building materials used in India and the country

is the second largest producer of bricks, representing over 10% of global production. There is no

reliable inventory of brick kilns or of brick production in the country and estimates vary

significantly by organizations reporting these numbers. Singh and Asgher (2005) have reported

an estimated 100,000 operating units producing about 140 billion bricks annually in India while

a more recent Central Pollution Control Board estimate reports 150,000 brick kilns operating in

the country in 2008. Coal is the main fuel used for firing bricks. The annual consumption of coal

in brick kilns is estimated to be around 25 million tonnes.

The majority of brick production takes place in the unorganized, small-scale/micro sector. Brick

making in India is a traditional, unorganized industry generally confined to the rural and peri-

urban areas. A major proportion of bricks are made using very basic tools and techniques.

Primitive brick kilns have been recognized as having large environmental, health, and a range of

social problems. Historically, fired clay brick has been the material of choice for small

residential construction in rural and urban areas and is expected to remain the primary choice

even for the next two decades. More recently however, the availability of good quality bricks has

been on the decline and demand has been growing due to increasing construction activity. The

perception among end users on alternate walling material is also gradually changing and

masonry material such as concrete blocks is gaining acceptance. Although brick manufacturers

face several barriers in labor and input costs, and alternate material have been gradually filling

the demand gap and entering the mainstream, bricks are still expected to dominate the walling

material landscape over the next two decades.


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The brick industry in the Gangetic plain differs from the brick industry in peninsular and coastal

India. The Gangetic plains of North India account for about 65% of total brick production.

Punjab, Haryana, Uttar Pradesh, Bihar and West Bengal are the major brick producing states in

this region. Brick kilns, generally of medium and large production capacities (210 million

bricks per year), are located in clusters around major towns and cities (Singh and Asgher, 2005).The availability of good fertile alluvium soils in north India has caused the fringe areas of cities

in this region to be dotted with brick kilns and consequently is a significant force in bringing

about land use/ landcover changes around cities. Peninsular and coastal India accounts for the

remaining 35% of the brick production. In this region bricks are produced in numerous small

units (production capacities generally range from 0.1 to 3 million bricks per year). Gujarat,

Orissa, Madhya Pradesh, Maharashtra and Tamil Nadu are important brick producing states in

the peninsular plateau and coastal India. Apart from coal, a variety of biomass fuels such as

firewood, dry dung, rice husk are used for firing bricks.

Brick production

The primary material used in the production of bricks is clay. Argillaceous materials used are

mixed well with sand to improve the workability. Clay is relatively easy to extract as it does not

usually lie too deep in the ground. After the top soil has been removed and the clay extracted, it

is sieved, blended and mixed well with water, either manually or with mechanical mixers. The

forming of bricks with the prepared clay is done manually or by moulding machines.

Hand moulding is done a four sided mould using a soft mud process where soil with high

moisture content is used to facilitate easier pressing. The moulding is done on level ground and

the wet brick is sun dried. A five sided mould is used to shape a relatively stiffer mud into a

brick. The wet brick is released onto a level platform by turning the brick upside down. These

bricks generally have a frog on one of the faces. Wire cut bricks are produced by a mechanized

operation. The selected soil is plugged adequately and then extruded into a continuous slab of

clay. This slab is then sliced by a wire frame into a number of bricks.

Cement Concrete Blocks

Overview

Cement is a collective name for mineral binders in powder form, which sets to become solid

when mixed with water. Cement reacts with water in a hydrating process. The cement most

usually used in building today is Portland cement. The main constituent of Portland cement is

limestone (65%), which is broken up and ground with quartz sand and clay or just clay. The


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mixture is calcined in kilns at 14001500 C and sintered to small pellets called cement clinker.

After firing, the mass is ground again with additives such as gypsum to regulate setting. The

cement industry is an energy intensive industry with total energy cost typically accounting for

40-45% of production costs. At present, about 96% of Indias cement production is from dry

process kilns, which is considerably less energy intensive than wet process kilns (InfrastructureLeasing and Financial Services, 2009).

The manufacture of concrete blocks is based on the principle of densification of a lean concrete

mix to make a regular shaped, uniform, high performance masonry unit. Blocks typically

manufactured are solid or hollow and are available in sizes of 400 mm x 200 mm x 200 mm, 400

mm x 200 mm x 150 mm, and 400 mm x 200 mm x 100 mm. The material has high potential in

areas where fired bricks are not easily available or are of poor quality. In large scale construction

such as apartments and commercial complexes, concrete blocks have found favor among

developers primarily because of the advantages of faster construction with the larger sized blocks

and also due to costs being comparable with fired clay bricks. The slightly lower width of

concrete blocks in relation to standard-size fired clay bricks also offers a higher usable area of

constructed space. The demand for concrete blocks has therefore grown considerably in urban

areas and small production units have been established around towns and cities in India.

However, the quality of blocks produced at these units has not been consistent and is a cause for

concern. Certain large developers have established their own cement concrete block

manufacturing units to overcome this issue. The demand for cement concrete blocks has been

growing rapidly over the past decade and has also been gaining in acceptance for use in

residential buildings both in urban as well as semi-urban areas.

Production of cement concrete blocks

The basic raw materials for the manufacture of cement concrete blocks are cement, fine

aggregate and coarse aggregate. Wastes generated by stone crushers, quarrying and stone

processing units can also be used as aggregates and has now become increasingly common.

Concrete blocks are usually produced using a semi-mechanized stationary type machine.

Although manual moulding requiring hand tamping is an alternative method that does not require

electrically operated machinery, this process is low in productivity and often with high variation

in quality of the product. A fully mechanized system which combines compression and vibration

is also used in a few instances but these are large scale units that require significant investments.

Adequate vibration of the mix, best obtained in high quality machines, can lower the cement

content substantially without compromising on the strength of the block. Mechanization in the


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moulding process provides adequate compaction of the mix and can yield uniform dimensions of

blocks. Very little water is used in the mix where compaction and vibration is mechanized.

Blocks need to be cured for a period of 10-14 days and this part of the production process results

in a high level of water consumption overall.

A case study of a concrete block unit in Bangalore that uses a semi-mechanized productionprocess was carried out as part of this study. The mixing of the raw materials is done using a

concrete mixer and a concrete block making machine is used for moulding. The annual

production of this unit is equivalent to 459,000 blocks of 400 mm x 200 mm x 200 mm size. The

quantity of sand, cement and stone dust used to produce one block of this size was estimated to

be 5.80 kg (25%), 3.48 kg (15%) and 13.92 kg (60%) respectively. The total water used in the

mix and for curing the blocks was estimated to be 33.0 liters. Sand and stone dust are transported

to the unit from a distance of about 40 km and 10 km respectively.materials mixed are not

adequately controlled. This could lead to non-uniform compressive strengths that vary by batch

of mixes.The green bricks are stacked and allowed to dry in a covered area until the moisture

content is reduced to about 2%. This generally is a natural drying process. When clay is heated

up to boiling point the water in the pores evaporates, and at 200300 C the hydrate water

evaporates. After this change, the clay will not revert to soft clay with the addition of water,

unlike an air-dried earth block.

In India, the Bulls Trench Kiln (BTK) accounts for around 70% of brick production and is

prevalent in the Indo-Gangetic plains as well as in certain pockets around the country. Clamps

are temporary firing structures adopted to manufacture bricks on a small scale and used widely

all over peninsular India. Down-draught kilns, Vertical Shaft Brick Kilns (VSBK), Hoffmann

kilns, and zig-zag kilns are some of the other types of kilns used but make up less than 5% of all

kilns in the country. The energy and environmental performance of different types of kiln

technologies using different types of fuels was monitored in the second component of this study.

Seven kilns across India and one tunnel kiln in Vietnam have been assessed. These kilns all use

clay (99.5% with 0.5% sand) as the raw material to produce bricks. A more detailed description

of these kilns is provided in the Cleaner Brick Industry for India study report.

Clay Bricks

overview

Clay bricks are used in a wide range of buildings from housing to factories, and in the

construction of tunnels, waterways, bridges etc. Their properties vary according to the purpose


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for which they are intended, but clays have provided the basic material of construction for

centuries. Brick is the oldest manufactured building material, and much of its history is lost in

antiquity. The oldest burnt or fired bricks have been found on the sites of the ancient cities of

Babylonia, some of which are estimated to be about 6000 years old. Brick is, after all, virtually

indestructible. The industry developed on traditional lines, using hand-making processes for themost part. The first patent for a clay-working machine was granted in the year 1619.

Mechanisation, however, did not begin to take the place of manual methods until the middle of

the nineteenth century.

The moulded products were fired in relatively inefficient intermittent or static kilns until about

1858, when Hoffmann introduced a continuous kiln, which enabled all processes connected with

the firing to be carried out concurrently and continuously.

Since the introduction of clay working machinery and the Hoffmann Kiln, the Industry has made

great progress, particularly since 1930, the output of bricks in Great Britain was doubled between

1930 and 1938.

Raw Materials

What is clay?

In brick-making terms, clay covers a range of naturally occurring raw materials which are used

to make a product. The clays vary considerably in physical properties, colour, hardness etc, and

mineralogical content. They do, however, have certain properties in common. They have the

ability to be crushed and mixed with water to form a plastic material which can be moulded into

various shapes. This can then be fired to a high temperature during which process it attains a

hard, weather resistant characteristic. The key, in geological terms, is the mineral content of the

raw material. This is common to all clay types.Pure clay mineral is formed from the erosion and

weathering of primary igneous rocks. The clay mineral is transported away by the action of

water, wind, ice etc., and re-deposited elsewhere. In the process it picks up a number of

impurities, Quartz, mica, Calcium Carbonate (lime), Iron Oxide etc, etc. The subsequent deposit

becomes a sedimentary rock. Due to variances in the age of the deposit, the conditions of its

deposition and the impurities involved there will be variations between different clay types and

even on occasions within the same deposit. These variations may affect the brick making process

and the properties of the finished product. Clay Winning The choice of method of clay winning

will depend on the depth, thickness, hardness and physical geology of the clay beds. The usual

method for winning clay (extracting from the quarry) is once or twice a year by heavy plant


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machinery, whether it be excavators, back actors etc, to stockpile large amounts. The

advantages of bulk winning are that it can take place during good weather, a large reserve close

to the factory means that breakdown of quarry plant is not critical to the production schedule.

The layering of the stockpile from large reserves helps to eliminate localised variations in the

clay strata.by Clay being extracted from a quarry by a mechanical digger. Laboratory testing ofthe clays from different parts of the quarry determine the likely characteristics of the layers and

clay is mixed according to the required properties of the finished item. Particular attention is

given to environmental factors both during the clay win and when restoring the landscape after

excavations are complete.

Clay Preparation

Clay preparation methods may have to accommodate the physical characteristics of the raw

material and special provision may have to be made to deal with certain impurities.Preparation

consists of transforming the clay rock into plastic mouldable material by a process of

grinding and mixing with water. A typical factory might have a Primary crusher, these are used

to break down large lumps of rock to manageable size, which can then be fed to a Secondary

crusher, for example Pan mill, where the clay is reduced in size further. Water can be added here

or if it is a dry pan the clay is reduced to dust and water added later. Further crushing takes place

through conveyor rollers reducing the clay particles to about 1-2mm.

Forming The Brick Shape

Most bricks are formed by one of two basic processes.

Extrusion

The clay body is mixed to a fairly stiff texture and is then loaded into an extruder where a worm

screw pushes it along a barrel into a vacuum chamber which compresses it through a taper and

out through a die. The die is machined to a precise size and shape larger than the finished size of

the brick, calculating how much the clay will shrink during the drying and firing process. The

clay emerges as a continuous brick shaped column. Initially this is smooth but it can be modified

by removing a thin sliver from the top and sides using a taught wire to produce a wiredrag

effect or by placing textured rollers over the column to create a rusticated effect or even by

blasting the column with sand. The clay column is then cut into single bricks and palletised ready

for the dryers or in some factories, are loaded directly onto kiln cars. Extruded bricks are

generally perforated and can be solid but cannot be frogged.


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Soft mud moulding.

This covers a number of processes where bricks

are formed in mould boxes. There are several methods but all have a common theme. Soft clay

is thrown into a mould, a mould release medium prevents the clay from sticking to the box

(sand, oil or water). The excess clay is stuck off from the top of the mould and the bricks areturned out. In its most simple form this is done by hand by a craftsman who would produce one

brick at a time. This is labour intensive, slow and expensive usually only used now for making

special shapes or decorative bricks. For standard bricks large automated machines can replicate

the hand-making process much quicker by using banks of mould boxes continually on a circuit

where the boxes are washed, sanded, filled with pre sanded clots of clay, struck off level and the

formed brick turned out. Clots of clay being mechanically thrown into moulds Because the clay

is dropped into the moulds a creased effect is achieved. Soft mud pressing is achieved in a

similar way with the moulds but the clay is pressed into them creating a smoother, sandy

texture. A variation of this process is water-struck where water is used as the release medium. A

relatively smooth, sand free texture is achieved. Again the boxes are made larger to

accommodate clay shrinkage during the rest of the process. As a general rule, moulded bricks

tend to be frogged (a indentation in one or more of the bed surfaces) although some are also

solid.

Drying

Before the bricks can be fired, as much moisture as possible must be removed or they will

explode in the kilns. Drying involves the removal of water from the wet brick in such a way as to

dry them out evenly from inside out. If the outer skin of the brick dries first it becomes

impossible for the moisture inside to escape. In the kiln the extreme temperatures will force out

this moisture and some cracking may occur. To prevent this happening the dryers are kept at

temperatures of about 80120 degrees centigrade and the atmosphere is very humid keeping the

exterior of the brick as moist as possible. This is monitored very closely to reduce surface

cracking. The bricks will shrink in the dryers as the clay particles come together and they

become strong enough to be stacked, but at this stage they have no weather resistant qualities.

Drying schedules vary but between 18 to 40 hours is typical for an automated plant. Special

shapes and large units can take up to a week or more. The dry bricks are then set onto kiln cars

ready to be fired.


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Firing

Firing temperatures vary considerably between different clay types and are often quite critical.

During firing, bricks undergo a physical change. Clay particles and impurities are fused together

to produce a hard durable and weather resistant product. This is called vitrification. This is

usually accompanied by further shrinkage and a colour change. Temperatures vary greatlydepending on clay type but are generally in the range of 900 1200 degrees centigrade.

Obviously bricks cannot suddenly be subjected to these temperatures so firing is in three stages.

1. Pre heatingthis ensures total dryness of the brick and utilises combustion gasses in the kiln

to raise the brick temperature. (Where wet setting has taken place great care needs to be taken at

this stage)

2. Firing- A fuel, usually natural gas, LPG, oil or coal is used to raise and maintain the

temperature to the required level over a few hours.

3. CoolingCold air is drawn into the kiln to cool the bricks slowly ready for sorting and

packing. This air becomes hot and can be drawn off and recycled for use in the drying process.

KILNS

There are several different types of kiln but they can be allocated to two main categories.

Intermittent kilnsThese are static, usually small kilns and are used for firing small batches of

products eg. Special shapes. The kiln is loaded with ware, taken through the firing process then

unloaded.

Continuous kilns

For large scale production continuous kilns are more economical and are capable of turning out

large

quantities of bricks at a steady constant rate.

There are two main types of continuous kiln Chamber and Tunnel.

Chamber kiln In its simplest form a chamber kiln is an annular tunnel divided off into chambers

(usually 12-20). A section of the kiln (about 4-5 cambers) is being fired at any one time. The

firing is drawn round the kiln with chambers being lit in front of the firing and the chambers

behind are allowed to go out.

Bricks are loaded into the kiln in front of the fire and pre-heat for 1-2 days before the fire reaches

them. The bricks then fire for 2-3 days. Once the fire has passed, the bricks cool before being

removed from the kiln. They are then replaced with fresh dry bricks awaiting the fires next

circuit.


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Abmt Notes