Transcript File

GYANMANJARI INSTITUTE OF TECHNOLOGY
CHAPTER 6
BUILDING MATERIALS
INTRODUCTION
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STONE
BRICK
LIME
CEMENT
TIMBER
SAND
AGGREGATES
MORTAR
CONCRETE
BITUMEN
STONE: Stone is a natural engineering material.
 Stones are derived from rocks, which form the earth’s crust
and have no definite shape and structure but it can be a
mixture of two or more materials.
TYPES OF STONES
Geological
classification
Igneous Rocks
Sedimentary
Rocks,
Metamorphic Rocks
Physical
Classification
Stratified,
Unstratified,
Foliated
Chemical
classification
Siliceous,
Argillaceous,
Calcarious.
Requirements of Stone
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Structure
Appearance & Color:-uniform color
Texture:-arrangement of its constituent minerals.
Specific gravity:- should have sp. Gravity in between 2.4
to 2.7.
Water absorption:- Not more than 5%.
Durability:- Depends upon chemical composition
Strength:- Crushing strength more than 100N/mm2.
Hardness:-Better resistance against abrasion.
Facility of Working and Dressing
Uses of Stone
 They are used in hydraulic structures like dams
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and bridges.
They are used in retaining wall masonry to retain
soil.
They are used as road metal in road construction.
They are used as ballast for permanent way in
railways.
They are used to make concrete in the form of
coarse aggregate.
Properties of Stone
 Silicious rocks are hard and durable. They are not
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easily affected by weathering actions.
Argillaceous rocks may be dense and compact or they
may be soft.
The Durability of calareous rocks will depend upon the
constituents present in surrounding atmosphere.
Marble and quartzite have compact crystalline
structure.
Igneous rocks contain many minerals. Various
minerals having wide range of different distinctive
characteristics.
Brick
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Requirements of Bricks
The colour of the brick should be red or
copper and uniform.
It should be well burnt in kilns.
The surface should be even and free from
cracks.
The edges should be sharp.
 Composition of Good brick earth
(1) Alumina (Al2O3):
It is the chief constituent of a good brick earth. A content of about
20% to 30% is necessary to form the brick earth of a good quality. It
imparts plasticity to the earth so it helps in the moulding of the brick
earth.
(2) Silica (SiO2):
It exists in the brick earth either free or combined. As free sand it is
mechanically mixed with clay and in combined form it exists in
chemical composition with alumina. A good brick earth should contain
about 50% to 60% of silica.
(3) Lime(CaCO3):
A small quantity of lime not more than 5% is desirable in good brick
earth. It should be present in very fine state, because even small
particles of size of a pin-head can result in the flaking of the brick.
(4) Oxide of Iron (Fe2O3):
Iron oxide performs two functions, first it helps in fusing of the sand
like lime and second it provides the red color to the bricks. It is kept
below 5 to 6% because excess of it may result in the dark blue or
black color of brick.
(5) Magnesia:
It is used to provide a yellow tint to the bricks. Its content is only
about 1% or less.
Types of Bricks
 Conventional / Traditional bricks : Size 23 cm x
11.4 cm x 7.6 cm
 Standard / Modular : Size : 19 cm x 9 cm x 9 cm
Classification of Bricks
(1) First class bricks:
These first class bricks are table moulded and of uniform shape and they are
burnt in kilns. The surfaces and edges of the bricks are sharp, square,
smooth and straight. They comply with all the qualities of good bricks.
These bricks are used for important work of permanent nature.
(2) Second class bricks:
The second class bricks are ground moulded and they are burnt in kilns. The
surface of the second class bricks is slightly rough and shape is also
slightly regular. These bricks may have hair cracks and their edges may
not be sharp and uniform. These bricks are commonly used at places
where brickwork is to be provided with a coat of plaster.
(3) Third class bricks:
These bricks are ground-moulded and they are burnt in clamps. These
bricks are not very hard and they have rough surfaces with irregular and
blunt edges. These bricks give dull sound when they are struck together.
They are used for unimportant works, temporary structures and at places
where rainfall is not heavy.
(4) Fourth class bricks:
These are overburnt bricks with irregular shape and dark colour. These bricks
are used as aggregate for concrete in foundations, brick floors, surkhi,
roads, etc. because of the fact that the overburnt bricks have a compact
structure and hence they are sometimes found to be stronger than even
the first class bricks.
Uses of brick
 Bricks are used in wall masonry construction of
building
 Used in brick lintel construction
 Bats of brick are used in concrete in foundation
work
Properties of bricks
 They are durable.
 They are low cost material.
 They possess good strength.
 They are easily available.
 Brick are light in compared to stones.
Lime
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Requirement of lime
it should set easily.
it should have low shrinkage.
it should not contain impurities.
It should be moisture resistant
It should slake easily with water.
Types of lime
(1) Fat Lime/Pure Lime:- Fat lime is also known as pure lime, white lime or rich
lime, this is manufactured using the purest form of the limestone. It is popular with
its name as fat lime since its volume is increased to about 2 to 2.5 times its
originally volume after getting slaked.
(2) Hydraulic Lime: This lime has the hydraulic property, means it can set under
the water also. It contains clay and some amount of ferrous oxide also. This is also
known as water lime. Depending upon the amount of clay hydraulic lime is classified
into further three categories:
(a) Feebly hydraulic lime
(b) Moderately hydraulic lime
(c) Eminently hydraulic lime
Increase in the percentage of clay makes the slaking difficult and thus increases the
hydraulic property of lime. With about 30 per cent of clay lime resembles the color
of cement.
The color of fat lime is not white therefore fat lime looks more sanitary than the
hydraulic lime.
(3) Poor Lime: Poor lime contains more than 30 percent of clay therefore it is also
known as impure lime. It slakes very slowly and also does not dissolve into water. It
has poor binding property and its color is muddy white.
This lime forms very poor mortar and so such lime can be used for inferior types of
work or at places where good lime is not available.
Uses of lime
 Lime is uses in the treatment of water and waste
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water.
It is used in the manufacture of glass, refractory,
sand lime bricks and paints.
It is used as lime mortar for masonry work of
buildings.
It is used for plastering and white washing of
buildings.
It is used as lime concrete to make water proof
structure.
Properties of lime
 It has good workability.
 It stiftens quickly.
 It has low shrinkage.
 It has good resistant to moisture.
 Lime possesses good plasticity.
Cement
Requirements of cement
 Cement should Cement should not possess of
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alumina which may reduce strength.
not contain alumina in excess as it weakens the
cement.
A very small amount of sulphur is added in
cement to make sound cement.
It should found cool when touch by hand.
it should be in fine powder form while checking
with first finger and thumb.
 Functions of Cement Ingredients:
 Lime (CaO): This is the important ingredient of cement and I s proportion is
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to be carefully maintained. The lime in excess makes the cement unsound and
causes the cement to expand and disintegrate. On the other hand, if lime is in
deficiency, the strength of cement decreases and it causes cement to set
quickly.
Silica (Si02): This is also an important ingredient’ of cement and it gives or
imparts strength to the cement due to the formation of dicalcium and tri
calcium silicates. If silica is present in excess quantity, the strength of cement
increases but at the same time.
Alumina (AI203): This ingredient imparts quick setting property to the
cement. It acts as a flux and it lowers the clinkering temperature. However the
high temperature is essential for the formation of a suitable type of cement
and hence the alumina should not be present in excess amount as it weakens
the cement.
Calcium sulphate (CaS04): This ingredient is in the form of gypsum and its
function is to increase the initial setting time of cement.
Iron oxide (Fe203): This ingredient imparts color, hardness and strength to
the cement.
Magnesia (MgO): This ingredient, if present in small amount, imparts
hardness and color to the cement. A high content of magnesia makes the
cement unsound.
Sulphur (S): A very small amount of sulphur is useful in making sound
cement. If it is in excess, it causes cement to become unsound.
Alkalis: The most of the alkalis present in raw materials are carried away by
the flue gases during heating.
Types of cement
 Ordinary portland cement(opc)
 Rapid hardening portland cement
 Quick setting cement
 Pozzuolana portland cement
 Low heat cement
 Blast furnace cement
 White cement
 Sulphate resisting cement
 Coloured cement
Uses of cement
 It is used in making joints for drains ,pipes.
 It is used to prepare RCC structures of building by
using reinforcement with cement concrete.
 it is used in construction of buildings, bridges,
tanks, domes, flyovers, dockyard etc.
 It is used to prepare cement mortar for building
construction works like masonry, plaster, painting,
flooring etc.
 It is used to prepare cement concrete for various
construction works.
Properties of cement
 Physical properties of cement
 Mechanical properties of cement
 Chemical composition
 Fineness
 Soundness
 Setting of cement
Timber
Requirements of timber
 It should be dense.
 It should have uniform texture.
 It should have dark uniform color.
 It should be workable, good machinability.
 The medullary rays should be compact.
Types of Timber
 Natural timber
babul, oak, pine, mango, sal, teak, neem,
palms, chir.
 Industrial timber
veneers, plywoods, fiberboards, impreg
timber, compreg timber.
Uses
 Railway sleepers, bridges, pipes.
 Furniture, decorative pieces, doors.
 Packing material, piles, cart wheels.
 Poles, pen, rafter.
 Roofs, partition walls, boats etc.
Properties of timber
 It has low heat conductivity.
 It has small bulk density.
 It is relatively high strength.
 It is susceptible to decay.
 It is susceptible to flame.
Sand
Requirements of sand
 It should be clean.
 It should be well graded.
 Maximum permissible clay content is 3 to 4% in
sand.
 It should contain sharp, angular grains.
 It should not contain salts which attract moisture
from the atmosphere.
Types of sand
 Natural
natural sand is obtained from pits, river
beds and sea beds.
 Artificial
artificial sand is formed by decomposition
of sandstone due to various weathering
effects.
Uses
 Sand is useful in various construction activities
like masonry work, plaster work, flooring and
concrete work.
 Sand is used in cement mortar, plan cement
concrete , reinforced cement concrete and
prestressed concrete as key ingradient in building
construction.
Properties of sand
 It is naturally available material
 It is durable
 It mix with binding material easily
 It has shiny luster
 It is of whitish brown color.
Aggregates
Requirements of Aggregates
 Aggregates should be sufficiently strong.
 Aggregate surface should be rough and free form
cracks.
 Aggregate should have good soundness.
 Aggregate should have good adhering
binding material.
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Types
 Fine aggregates
Size of aggregate is 4.75 mm or less is termed as
fine aggregates.
 Coarse aggregates
Size of aggregates 80mm to 4.75 mm is
known as course.
Uses
 Fine aggregates are used to prepare cement
mortar, lime mortar and cement concrete.
 Course aggregates are used to prepare cement
concrete bituminous pavement, rigid pavement
etc.
 They are used in construction of beams, columns,
slab, lintel etc.
Properties of aggregates
 They are insoluble in water.
 They are of moderate weight.
 They are strong and durable.
 They have resistance to scratches.
 They have resistance to corrosion and decay.
Mortar
Requirements of mortar
 It should have good adhesion with bricks, stones.
 It should resist penetration of rain water.
 It should be cheap, durable, and workable.
 It should be set quickly.
 The joints formed by mortar should not develop
cracks.
Types
 As per type of binding material.
like cement, lime, gauged, gypsum, surkhi.
 As per nature of application.
 As per density of the mortar.
 Special mortar.
Uses
 To bind the bricks or stones firmly in wall
construction work.
 They are used in plaster work as finishing
material to provide weather resistance joints of
masonry work are covered by plaster work. White
wash and color are applied on plastered surface
easily.
 Properties of mortar
 Mobility.
 Place ability.
 Water retention
Concrete
 Concrete is a mixture of cement/lime, sand,
crushed stone, water.
 TYPES OF CONCRETE
1. Plain cement concrete
2. Reinforced cement concrete
3. Precast concrete
4. Prestressed concrete
Properties of concrete
 Workability
 Strength
 Durability
 Dimensional stability
Bitumen
 Bitumen is an essential component of any pavement and is
used widely throughout the world.
 It can be termed as the building block of the pavements
without which all the pavement materials would behave
independently and thus will be deemed useless.
 Almost ninety percent of bitumen is used in road
construction. It is usually available in dark colors ranging
from brown to black.
CLASSIFICATION OF BITUMEN
 Cutback Bitumen:
Cut-back bitumen are those which are prepared with the addition of a
volatile to reduce the thickness of the binder.
 Fluxed Bitumen:
Fluxed bitumen are those bitumen which are prepared by the addition of
relatively non volatile oils to reduce the viscosity of the binder.
 Modified Bitumen:
Modified bituminous binder are those whose properties such as cohesive
strength, adhesive property, elasticity or viscosity have been modified by
the use of one or combined chemical agents.
 Asphalt:
Asphalt is a mixture of aggregates both fine (sand and filler) and coarse
(stone) and a bituminous binder. It typically contains approximately 4-7%
of bitumen. Asphalt is primarily used in road construction and its properties
depend upon the type, size and amount of aggregate used in the mixture,
all of which can be adjusted to provide the required properties for the
desired application.
Properties of Bitumen materials
1. Adhesive: Binds together all the components without bringing
about any positive or negative changes in their properties.
2. Water proof: Bitumen is insoluble in water and can serve as an
effective sealant
3. Strong: Though the coarse aggregates are the main load bearing
component in a pavement, bitumen or asphalt also play a vital role
in distributing the traffic loads to the layers beneath.
4. Durable: Bitumen lives up to twenty years if maintained properly
throughout the pavement life.
5. Versatile: Bitumen is a relatively easy to use material because of
its thermoplastic property. It can be spread easily along the
underlying pavement layers as it liquefies when heated making the
job easier and hardens in a solid mass when cooled.
6. Economical: It is available in cheaper rates almost all over the
world