Unit 1.civil engineering materials

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CIVIL ENGINEERING
MATERIALS
UNIT-1
6/16/2014Prepared by CHIRAG BHANGALE

•Manufacture of bricks is mostly a village industry.
•Bricks have been produced since the dawn of civilization in the sun
dried form.
• The Great Wall of China was made of both burnt and sun dried
bricks.
•Bricks have been used all over the world in every class and kind of
building.
•In places where plenty of clay is available, brickwork is cheaper.
• The cost of construction work is less with bricks. Bricks resist fire
and, hence, they do not easily disintegrate.
•The atmospheric effects are resisted by bricks of good quality.
•Bricks are obtained by molding clay in the rectangular blocks of
uniform size and then by drying and burning these blocks.
• Bricks are very popular as they are easily
available,economical,strong,durable & reliable
BRICKS
2 6/16/2014Prepared by CHIRAG BHANGALE

• The brick should be uniform in shape and should be of standard size.
• The brick when broken should show a uniform compact and homogeneous
structure free from voids.
• The brick should not absorb water more than 20 per cent for first-class bricks and 22
per cent for second-class bricks when soaked in cold water for a period of 24 hours.
• The brick should be hard enough. No impression should be left when scratched.
• The brick should not break into pieces when dropped from a height of 1 m.
• The brick when soaked in water for 24 hours should not show deposits of white salts
when allowed to dry in shade.
•The brick should have low thermal conductivity and should be sound proof. The
crushing strength of brick should not be below 5.5 N/mm2.
•The brick should be table moulded, well burnt and free from cracks with sharp and
square edges.
•The colour should be uniform and bright.
•The bricks should give a good metallic sound when struck with each other.
Properties of Bricks:

Types of Bricks:
Conventional Bricks
Standard Bricks
Conventional Bricks:
The dimensions of conventional bricks vary from 21 to 25 cm in l
ength,10 to 13 cm in width and 7.5 to 10 cm in thickness in
different countries.
But the commonly adopted size of conventional brick is
23x11.4x7.5 cm.
Standard Brick:
In different countries different sizes of bricks are used. Therefore
to uniform size of the brick throughout the country, ISI suggested
a uniform brick size which known as standard brick.
The nominal size of the brick is 20x10x10cm and the actual size
is 19x9x9cm.

There are various types of bricks used in masonry.
1.Common Burnt Clay Bricks
2.Sand Lime Bricks (Calcium Silicate Bricks)
3.Engineering Bricks
4.Cement Bricks
5.Fly ash Clay Bricks
Bricks Type:
Common Burnt Clay Bricks:
•Common burnt clay bricks are formed by pressing in molds. Then
these bricks are dried and fired in a kiln.
•Common burnt clay bricks are used in general work with no special
attractive appearances.
•When these bricks are used in walls, they require plastering or
rendering.

•Sand lime bricks are made by mixing sand, fly ash and lime
followed by a chemical process during wet mixing. The mix is then
molded under pressure forming the brick. These bricks can offer
advantages over clay bricks such as:
•Their color appearance is grey instead of the regular reddish color.
•Their shape is uniform and presents a smoother finish that doesn’t
require plastering.
•These bricks offer excellent strength as a load-bearing member.
Sand Lime Bricks:
Cement Bricks:
•Burnt bricks are becoming more costly due to increasing fuel cost. Therefore
hollow cement block are increasingly used in construction.
•In this process, cement mortar is pressed in machine mould. The mould is hollow
in the center to reduce weight of the brick and cost.
•These bricks are very strong. They keep the house cool since they are hollow in
between and air is bad conductor of heat.
•They need less material for plaster & less expenses on outdoor colour. Size -
12x8x4 inch6 6/16/2014Prepared by CHIRAG BHANGALE

Engineering Bricks:
Fly Ash Clay Bricks:
•Engineering bricks are bricks manufactured at extremely high temperatures, forming
a dense and strong brick, allowing the brick to limit strength and water absorption.
•Engineering bricks offer excellent load bearing capacity damp-proof
characteristics and chemical resisting properties.
•Fly ash clay bricks are manufactured with clay and fly ash, at about 1,000
degrees C.
•Some studies have shown that these bricks tend to fail poor produce pop-
outs, when bricks come into contact with moisture and water, causing the
bricks to expand.

Uses of bricks:
•Bricks are extensively used as a leading material of construction.
•A fire brick is used for lining the interiors of ovens, chimneys and furnaces.
•Broken brick are used as a ballast material for railway tracks, and also as a
road metal.
•Bricks are extensively used for construction of load-bearing walls and
partition walls.
•Bricks are also used for face-work when artistic effect is required.

STONES
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 The stones which are suitable for the construction of the
structures such as retaining walls, abutments, dams, barrages,
roads etc are known as building stones. Building stones should
possess enough strength and durability.
Stones have been considered as one of the popular building
material from the olden days due to their availability in
abundance from the natural rocks

COMMON USES OF BUILDING STONE:
Is used in foundations of buildings,
It is used in construction of dams, barrages, etc,
In its crushed (powdered form) it is used as artificial sand,
It is used as raw material for manufacturing of cement,
In its broken form it is used as material for construction of road
and railway tracks,
It is used as decorative material in buildings,
It is also used as parts of buildings such as lintels and arches,
etc,
It is also used as thin slabs for building roofing,
It is also used for ornamental works in buildings,
In its broken form it is in the manufacturing of concrete,

CHARACTERISTICS OF GOOD BUILDING STONES:
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(1) Hardness:
Hardness denotes several qualities of stones such as resistance to cutting and
resistance to abrasion (rub with each other). Specially stones are used in case of roads
and railway tracks. To check the hardness of stones various tests are conducted in the
laboratories. The more important tests to check the hardness is Loss Angles Abrasion
test. It depends upon the nature of its constituent minerals.
(2) Durability:
Durability is the power of stone to resist atmospheric and other external effects.
It depends upon:
Chemical composition,
Physical structure,
Resistance to weathering effects,
Place where it is used
Stone which contain silicates will be durable than those stone which contain
calcareous substances.

(3) Porosity and Absorption:
Stone can hold water in two ways
Either through porosity or absorption
For building purposes, the better stones are those which are less porous because
they will absorb less moisture. Porous stones damaged easily.
(4) Decomposition:
Gases and acids in rain water dissolve some constituents of stone and cause the
stone decay.
(5) Disintegration:
In cold countries water freezes and expands and thus disintegrates the stones.
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Reliability:
When exposed to fire stone should be reliable (good in quality).
Weight:
This is an important characteristic of stone. It depends upon the type of structure
of stone in which we shall use.
E.g. we shall use heavy stones in the construction of the dams, bridges, etc.
Strength:
It is power of stone to sustain pressure or resistance to crushing force.
Average crushing strength of stone is 3 tons per square inch.

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Appearance and color:
Highly colorful stones are preferred for architectural purpose but
those are soft and thus less durable. Therefore, lighter stones are
preferred than to darker ones.
Physical Strength:
Crystalline structures are more durable than non-crystalline
structure stone
Seasoning Qualities:
A good building stone should have good seasoning qualities. All the
stones contain some moisture which is known as quarry sap stones.
The period 3-6 months are enough for seasoning.
Fire resistance:
A good building stone should be fire resistant. Some stones such as
basalt and trap resist fire very well but some varieties of igneous and
metamorphic stones are very weak against fire.

CLASSIFICATION OF ROCKS (STONES) OR
VARIETIES OF STONES:
There are three main classes of rocks.
(1) CHEMICAL CLASSIFICATION:
Chemically stones are stones are classified into three groups.
(i) Argillaceous Rocks:
Argillaceous or clay stones are those stones which contain (alumina Al2O3) (clay) as
principal constituent. These stones are less durable stones. All clay stones belong to this
group.
The examples of argillaceous rocks are Slate, Laterite, etc.
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(ii) Silicious Rocks:
The stones which contain (Silica SiO2) as principal constituent are called silicious
rocks. These stones are durable stones.
The examples of silicious rocks are granite, Quartzite and Sand stone etc.
(iii) Calcareous Rocks:
The stones which contain calcareous material (CaCO3) as principal constituent are
called calcareous rocks. They also contain some proportion of siliceous and clay
matter.
The examples of calcareous rocks are marble stone and lime stone, etc.

(2) PHYSICAL CLASSIFICATION:
Physically rocks are classified as:
(i) Stratified Rocks:
The rocks which are split into thin slabs or layers easily are called stratified rocks. All
sedimentary rocks are essentially stratified and metamorphic rocks may be either
stratified or unstartified depending upon its parent rock.
The examples of stratified rocks are Slate, Sand stone and Lime stone.
(ii) Unstratified Rocks:
These rocks do not show sign of stratification and can not be easily split into thin
slabs or layers are called unstratified rocks. All igneous rocks are essentially
unstratified and metamorphic rocks may be either stratified or unstartified.
The examples of unstratified rocks are Granite, Basalt and Lime Trap.
(iii)Foliated rocks:
These rocks have a tendency to be split up in a definite direction only.
Foliated structure is very common in case of metamorphic rocks.

(3) GEOLOGICAL CLASSIFICATION:
Geologically stones are stones are classified into three groups.
(i) Igneous or Primary Rocks:
These are primary rocks which are formed from molten magma. They represent
different structural features depending upon the condition of solidification and
composition. Generally igneous rocks are strong and durable.
These are also called unsratified or eruptive rocks.
The examples of igneous rocks are granite, basalt, trap, etc.
(ii) Sedimentary or Secondary Rocks:
These are secondary rocks and are formed by the denudation and deposition of
previously existing rocks due to weathering actions. Water (rain) is the most powerful
and principal weathering agent. The other destructive agents are frost, winds and
chemical actions. The destructive agents break up the surface of earth which gets
further broken up when carried down by rains and rivers. When the velocity of water in
the rivers those broken particles are deposited in the river bed and thus sedimentary
rocks are formed.
These are also called aqueous and stratified rocks.
(OR)
The rocks which are formed by gradual deposition are called Sedimentary Rocks.
Examples: Lime stone, sand stone, etc.

(iii) Metamorphic or Tertiary Rocks:
Rocks which are formed due to metamorphic action of pressure or internal heat or by
both (or) alteration of original structure due to heat and excessive pressure) are called
Metamorphic Rocks.
Examples: Marble etc.
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(4)Practical classification
Practical classification is based on the usage. Practically stones have been
classified as granite, basalt, laterite, marble, limestone, sandstone and slate.

Uses of stone as a building material are:
•In stone masonry in places where it is naturally available.
•As coarse aggregate in cement concrete (crushed form of rock).
•As a roofing material in the form of slates.
•As a flag or thin slab for paving.
•As a soling material in the construction of highways and runways.
•As ballast for railway tracks.
•As a veneer for decorative front and interior of buildings.
•Limestone for construction of important buildings like temples, churches
and mosques.
•Limestone for the manufacture of cement and as a flux in blast furnace.

AGGREGATES
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 Aggregates provides the concrete with its body and strength act as filler
material to give the homogeneous mass of concrete along with cement
paste.
 Aggregate means mixing of cement& sand.
Types of aggregates:
(1)Fine aggregate
It is the aggregate whose particles pass through 4.75mm mesh
sieve but are retained on 0.15 mm mesh sieve completely.
Sand,crushed stones,ashes,etc.are the examples of the fine
aggregate.
(2)coarse aggregate
It is the aggregate whose particles completely pass through
75mm mesh sieve and are entirely retained on 4.75 mm mesh sieve.
Broken rocks ,ballast,brick bats,gravels,etc are the examples of
the coarse aggregate

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 Aggregates are insoluble in water.
 They are of moderate weight.
 They are not affected by weathering effect.
 They are strong and durable.
 They have resistance to corrosion.
 They have resistance to scratches.
 The aggregate should not contain any organic substances.
 The aggregate should not be porous.
 The aggregate should be well graded
 The surface texture of the aggregate should be rough.
 The particles of aggregate should be hard, strong,and durable.
Qualities(Properties) Aggregate:
•As a base material underneath highways,walkways,airport,runways,parking lots and
railroads.
•As a raw material used in combination with other resources to construct many of the
items we rely on to sustain our quality of living. These include:
•Houses and apartments;Roads,bridges and parking lots; schools and hospitals;
commercial buildings, airports and runways.
Uses of Aggregates:

CEMENT
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 The natural cement is obtained by burning and crushing the stones containing
clay,carbonate of lime and some amount of carbonate of magnesia.
 The natural cement is brown in color and its best variety is known as the
roman cement.
Ingredients of cement:
Al2O3 Alumina It makes the cement to set quickly
Sio2 Silica It provides strength
Cao Lime It provides strength
Fe2o3 Iron oxide Provide color,hardness and strength
Mgo Magnesia Provides hardness and color
CaSo4 Calsium
Sulphate
(gypsum)
Increase the initial setting time

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Uses of cement:
(I) Construction of Building: floors,beams,columns,roofing,bricks,plaster.
(II) Transportation:
roads,pathways,crossings,bridges,viaducts,tunnelsrunways and parking.
(III) Marine and water works:
pipes,culverts,drains,canals,weirs,dams,tanks,pools.
(IV) Civil work:

Cement concrete
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• Concrete is one of the most commonly used building materials.
• Concrete is a composite material made from several readily available
constituents (aggregates, sand, cement, water).
• Concrete is a versatile material that can easily be mixed to meet a variety of
special needs and formed to virtually any shape.
Advantages
•Ability to be cast
•Economical
•Durable
•Fire resistant
•Energy efficient
•On-site fabrication

Disadvantage:s
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•Low tensile strength
•Low ductility
•Volume instability
•Low strength to weight ratio
Constituents:
Mixture of aggregate and paste
paste 30 to 40%
portland cement 7% to 15% by Vol.
water 14% to 21% by Vol.
Aggregates 60% to 70%
carse aggregates
Fine aggregates
Admixtures0

Portland Cement
•Dry powder of very fine particles
•forms a paste when mixed with water
•chemical reaction-Hydration
•glue
•paste coats all the aggregates together
•hardens and forms a solid mass
Water
•Needed for two purposes:
•chemical reaction with cement
•workability
•Only 1/3 of the water is needed for chemical reaction
•Extra water remains in pores and holes
•Results in porosity
•Good for preventing plastic shrinkage cracking and workability
•Bad for permeability, strength, durability.

Aggregates
•Cheap fillers
•Hard material
•Provide for volume stability
•Reduce volume changes
•provide abrasion resistance
Admixtures
•Chemical
•set retarders
•set accelerators
•water reducing
•air entraining
•Mineral
•fly ash
•silica fume
•slags

Properties of fresh concrete
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Workability
Consistency
Segregation
Bleeding
Setting Time
Unit Weight
Uniformity

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 Requirement of good timber:
(I) It should have dark uniform color.
(II) It should be dense.
(III) It should be workable, good machinability.
(IV)It should have uniform structure.
(V) It should be free from defects like knots, shakes, cracks, splits, wraps etc.
(VI)There should not decay of timber due to fungi and insects like white ants and
termites.
(VII)IT should be fire-proof.
(VIII)It should be cheap.
(IX)It should be durable and effective.
•Timber denotes wood which is suitable for building or carpentry and for various engineering
and other purposes.
•The word timber is derived from Timbrian, which means to build. Timber thus denotes wood
which is suitable for building construction, carpenting or other engineering purposes.
TIMBER

•Appearance: A freshly cut surface of timber should exhibit a hard and
shining appearance.
•Colour: The colour of the timber should be preferably dark. A light
colour indicates low strength.
•Hardness: A good timber should be hard, i.e., it should offer resistance
when it is being penetrated by another body. The chemical present in
heartwood and the density of wood imparts hardness to timber.
•Durability: A good timber should be durable. It should be capable of
resisting the action of fungi, insects, chemicals, physical agencies and
mechanical agencies.
•Strength: A good timber should be strong for working as a structural
member such as joist, beams and rafter. It should be capable of taking
loads slowly or suddenly.
•Structure: The structure should be uniform and the medullary rays
should be hard and compact. The annual rings should be regular and
should be closely located.
Properties of timber:

•Mechanical wear: A good timber should not deteriorate easily due to mechanical
wear or abrasion. This property is essential for places where timber would be
subjected to traffic, like wooden floors and pavements.
•Toughness: A good timber should be tough. It should be capable of offering
resistance to shocks due to vibrations.
•Elasticity: This is the property by which the timber returns to the original shape
when load causing deformation is removed. This property is essential when timber is
used for bows, carriage shaft, etc.
•Fire resistance: Timber is a bad conductor of heat. A dense wood offers good
resistance to fire and it requires sufficient heat to cause a flame.
•Defects: A good timber should be free from serious defects such as dead knots,
flaws and shakes.
•Fibres: Timber should have straight fibres.
•Shape: A good timber should be capable of retaining the shape during conversion or
seasoning.
•Smell: A good timber should have a sweet smell.
•Sound: A good timber should give a clear ringing sound when struck.
•Weight: A timber with heavy weight is considered to be sound and strong.
Working condition: Timber should be easily workable. It should not clog the teeth of
saw and should be capable of being easily planed or made smooth30 6/16/2014Prepared by CHIRAG BHANGALE

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Seasoning of timber:
 When timber is first felled it is known as green timber and has a very high moisture
content. Before timber can be used it must be dried. Aim of seasoning is to dry out the
wood to suitable moisture content of 22% or less.
 Seasoning is the controlled process of reducing the moisture content of the timber so that
it is suitable for the environment and intended use. After seasoning timber is easier to
work with, because it is lighter, harder and stronger.
% Moisture
Content
Situation
22-20% Limit of air seasoned wood
20% Limit for the occurrence of dry rot
16% Outdoor furniture
12-14% Occasionally heated areas
11-13% Heated areas
9-11% Very heated areas

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Seasoning can be done by the following methods:
(I) Natural/Air seasoning
(II) Kiln seasoning
(I) Natural/Air seasoning: In this method, the seasoning of timber is carried out by
natural air and hence it is also sometimes referred to as air seasoning.
 Following procedure is adopted in the air seasoning:
(a) The timber in the long form is not usually fit for the process of seasoning. Hence it is
cut and sawn into suitable sections of planks or scantling.
(b) The timber pieces can either be stacked horizontally or vertically.
(c) The ground, where stack is to be constructed, is cleared and it is leveled for good
drainage.
(d) The platform of stack is made slightly higher, about 300mm, than the ground level.
For this purpose, the rows of bricks or concrete pillars are constructed.
(e) The timber pieces are sorted out according to length and thickness. They are then
arranged in layers, one above the other. The care should be taken to see that all
members in a particular layer are of the same thickness. If this precautions is not
taken, there are chances for timber to become warped or cracked.

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(f) Each layer is separated by spacers of sound dry wood. The usual dimensions of spacers
vary from 35mm x 25mm to 50mm x 35mm, the larger dimensions being the width.
(g) The distance between spacers depends on the size of timber members to be seasoned. It is
less for thin sections and more for thick sections.
(h) The length of stack is equal to length of timber pieces. The width and height of stack are
restricted to about 1500mm and 3000mm respectively.
(i) The stack is to be protected from fast blowing wind, rain and extreme heat of sun. hence
the stack should preferably be covered by a roof of suitable material.
 Advantages of air seasoning:
(I) No expensive equipment is needed.
(II) Small labor cost once stack is made.
(III) Environmentally friendly-uses little energy.
 Disadvantages of air seasoning:
(I) Slow drying rate
(II) Large area of space required for a lot of timber

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Kiln seasoning:
 Timber is stacked properly in the kiln by keeping open spaces for hot air circulations.
Initially temperature is maintained low slightly higher than the room temperature.
Successfully temp. is raised, humidity is reduced and air circulation is made faster.
 Advantages of kiln seasoning:
(I) Quicker due to higher temp., ventilations and air circulations.
(II) Achieve a lower moisture content.
(III) Defects associated with drying can be controlled.
 Disadvantages of kiln seasoning:
(I) It is expensive
(II) It requires supervision by a skilled operator
(III) Uses a lot energy

Uses of timber:
(I) For making doors, windows, and ventilators.
(II) Used for flooring and roofing material.
(III) Used for making furniture.
(IV)Used in the manufacture of sport goods, musical instruments etc.
(V) Used in making coaches, wagons, buses, boats etc.

Proofing Materials
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 Damp proofing in construction is a type of moisture control applied to building walls
and floors to prevent moisture from passing into the interior spaces. Damp problems are
one of the most frequent problems encountered in homes.
 Damp proofing includes several ways:
 A damp-proof course (DPC) is a barrier in a masonry wall designed to resist moisture
rising through the structure by capillary action such as through a phenomenon known as
rising damp. The damp proof course may be horizontal or vertical. A DPC layer is usually
laid below all masonry walls, regardless if the wall is a load bearing wall or a partition
wall.
 A damp-proof membrane (DPM) is a membrane material applied to prevent moisture
transmission. A common example is polyethylene sheeting laid under a concrete slab to
prevent the concrete from gaining moisture through capillary action.A DPM may be used
for the DPC.

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 Materials widely used for damp proofing include:
 Flexible materials like butyl rubber, hot bitumen, plastic sheets, bituminous
felts, sheets of lead, copper, etc.
 Semi-rigid materials like mastic asphalt
 Rigid materials like impervious bricks, stones, slates, cement mortar or cement
concrete painted with bitumen, etc.
 Stones
 Mortar with waterproofing compounds
 Coarse sand layers under floors
 Continuous plastic sheets under floors

Bituments
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 A black or dark brown viscous material, composed principally of high
molecular weight hydrocarbons, having adhesive properties, derived from
petroleum either by natural or refinery processes and substantially
soluble in carbon disulphide.
Asphalt
•Asphalt is a sticky, black and highly viscous liquid or semi-solid form of petroleum.
•It may be found in natural deposits or may be a refined product.
•it is a substance classed as a pitch.
•Until the 20th century, the term asphaltum was also used.
•The terms asphalt and bitumen are often used interchangeably to mean both natural and
manufactured forms of the substance

Asphalt

•The terms bitumen and asphalt are mostly interchangeable, except where
asphalt is used as an abbreviation for asphalt concrete.
•This article uses "asphalt/bitumen" where either term is acceptable.
•The terms asphalt and bitumen are often used interchangeably to mean both
natural and manufactured forms of the substance.
•In American English, asphalt (or asphalt cement) is the carefully refined
residue from the distillation process of selected crude oils.
• Outside the United States, the product is often called bitumen.
•Geological terminology often prefers the term bitumen.
•Common usage often refers to various forms of asphalt/bitumen as "tar",
such as at the La Brea Tar Pits.
•Another term, mostly archaic, refers to asphalt/bitumen as "pitch".
•The pitch used in this mixture is sometimes found in natural deposits but
usually made by the distillation of crude oil.
Bituments & Asphalt

Etymology
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 The word asphalt is derived from the late Middle English, in turn from
French asphalte, based on Late Latin asphalton, asphaltum, which is the
latinisation of the Greek ἄσφαλτος (ásphaltos, ásphalton), a word
meaning "asphalt/bitumen/pitch.
Modern usage
In British English, the word 'asphalt' is used to refer to a mixture of mineral
aggregate and asphalt/bitumen (also called tarmac in common parlance).
The earlier word 'asphaltum' is now archaic and not commonly used.
In American English, 'asphalt' is equivalent to the British 'bitumen'. However,
'asphalt' is also commonly used as a shortened form of 'asphalt concrete'
(therefore equivalent to the British 'asphalt' or 'tarmac')

Chemistry
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 The substance is completely soluble in carbon disulfide, and composed
primarily of a mixture of highly condensed polycyclic aromatic
hydrocarbons.
 it is most commonly modeled as a colloid, with asphaltenes as the
dispersed phase and maltenes as the continuous phase (though there is
some disagreement amongst chemists regarding its structure).
 It is almost impossible to separate and identify all the different
molecules of asphalt, because the number of molecules with different
chemical structure is extremely large.
 Most natural bitumen's contain sulfur and several heavy metals, such as
nickel, vanadium, lead, chromium, mercury, arsenic, selenium, and
other toxic elements.

Chemistry
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 Bitumen's can provide good preservation of plants and animal fossils.
 Asphalt/bitumen can sometimes be confused with "tar", which is a
similar black, thermoplastic material produced by the destructive
distillation of coal.
 During the early and mid-20th century when town gas was produced,
tar was a readily available product and extensively used as the binder
for road aggregates.
 The addition of tar to macadam roads led to the word tarmac, which is
now used in common parlance to refer to road-making materials.
 However, since the 1970s, when natural gas succeeded town gas,
asphalt/bitumen has completely overtaken the use of tar in these
applications.

Chemistry
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 Natural deposits of asphalt/bitumen include lakes such as the Pitch
Lake in Trinidad and Tobago and Lake Bermudez in Venezuela,
Gilsonite, the Dead Sea, asphalt/bitumen-impregnated sandstones
known as bituminous rock and the similar "tar sands".
 Asphalt/bitumen can be separated from the other components in crude
oil (such as naphtha, gasoline and diesel) by the process of fractional
distillation, usually under vacuum conditions.
 A better separation can be achieved by further processing of the heavier
fractions of the crude oil in a de-asphalting unit, which uses either
propane or butane in a supercritical phase to dissolve the lighter
molecules which are then separated.
 Further processing is possible by "blowing" the product: namely
reacting it with oxygen.
 This makes the product harder and more viscous.

Chemistry
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 Asphalt/bitumen is typically stored and transported at
temperatures around 150°C (300°F).
 Sometimes diesel oil or kerosene are mixed in before shipping to
retain liquidity; upon delivery, these lighter materials are
separated out of the mixture.
 This mixture is often called "bitumen feedstock", or BFS.
 Some dump trucks route the hot engine exhaust through pipes
in the dump body to keep the material warm.
 The backs of tippers carrying asphalt/bitumen, as well as some
handling equipment, are also commonly sprayed with a releasing
agent before filling to aid release.
 Diesel oil is no longer used as a release agent due to
environmental concerns.

Geological origin
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 Naturally occurring deposits of asphalt/bitumen are formed from
the remains of ancient, microscopic algae (diatoms) and other
once-living things.
 These remains were deposited in the mud on the bottom of the
ocean or lake where the organisms lived.
 Under the heat (above 50 °C) and pressure of burial deep in the
earth, the remains were transformed into materials such as
asphalt/bitumen, kerogen, or petroleum.
 Deposits at the La Brea Tar Pits are an example.
 There are structural similarities between asphalt/bitumen and the
organic matter in carbonaceous meteorites.
 However, detailed studies have shown these materials to be
distinct.

Modern usage
47
 The primary use of asphalt/bitumen is in road construction, where it is used as the
glue or binder mixed with aggregate particles to create asphalt concrete.
 Its other main uses are for bituminous waterproofing products, including production
of roofing felt and for sealing flat roofs.
Rolled asphalt concrete
The largest use of asphalt/bitumen is for making asphalt concrete for road surfaces
and accounts for approximately 85% of the asphalt consumed in the United States.
Asphalt concrete pavement material is commonly composed of 5% asphalt/bitumen
cement and 95% aggregates (stone, sand, and gravel).
Due to its highly viscous nature, asphalt/bitumen cement must be heated so it can be
mixed with the aggregates at the asphalt mixing plant.
Asphalt concrete paving is widely used in airports around the world.
Due to the sturdiness and ability to be repaired quickly, it is widely used for
runways dedicated to aircraft landing and taking off.

Modern Use
48
 Mastic asphalt
 Is a type of asphalt which differs from dense graded asphalt (asphalt concrete) in that it has a higher
asphalt/bitumen (binder) content, usually around 7–10% of the whole aggregate mix, as opposed to
rolled asphalt concrete, which has only around 5% added asphalt/bitumen.
 This thermoplastic substance is widely used in the building industry for waterproofing flat roofs and
tanking underground.
 Mastic asphalt is heated to a temperature of 210 °C (410 °F) and is spread in layers to form an
impervious barrier about 20 millimeters (0.8 in) thick.
Asphalt Emulsion
Slurry seal involves the creation of a mixture of asphalt emulsion and fine crushed
aggregate that is spread on the surface of a road.
Cold-mixed asphalt can also be made from asphalt emulsion to create pavements
similar to hot-mixed asphalt, several inches in depth and asphalt emulsions are also
blended into recycled hot-mix asphalt to create low-cost pavements.

Modern Use
49
 Asphalt Emulsion
 A number of technologies allow asphalt/bitumen to be mixed at much
lower temperatures.
 These involve mixing with petroleum solvents to form "cutbacks" with
reduced melting point, or mixtures with water to turn the asphalt/bitumen
into an emulsion.
 Asphalt emulsions contain up to 70% asphalt/bitumen and typically less
than 1.5% chemical additives.
 There are two main types of emulsions with different affinity for
aggregates, cationic and anionic.
 Asphalt emulsions are used in a wide variety of applications.
 Chipseal involves spraying the road surface with asphalt emulsion followed
by a layer of crushed rock, gravel or crushed slag.

Modern Use
50
 Asphalt/bitumen is used to make Japan black, a lacquer known
especially for its use on iron and steel.
 Asphalt/bitumen also is used in paint and marker inks by some
graffiti supply companies (primarily Molotow) to increase the
weather resistance and permanence of the paint and/or ink, and
to make the color much darker.
 Asphalt/bitumen is also used to seal some alkaline batteries
during the manufacturing process.
 Lacquer
 In a general sense, lacquer is a somewhat imprecise term for a clear or
coloured wood finish that dries by solvent evaporation.
 It is also often a curing process as well that produces a hard, durable
finish 6/16/2014Prepared by CHIRAG BHANGALE

Modern Use
51
 Petroleum production, alternatives and
bioasphalt
 Naturally occurring crude Asphalt/bitumen impregnated in
sedimentary rock is the prime feed stock for petroleum
production from "Oil sands“.
 currently under development in Alberta, Canada. Canada has
most of the world's supply of natural asphalt/bitumen, covering
140,000 square kilometers (an area larger than England).
 Asphalt/bitumen can now be made from nonpetroleum-based
renewable resources such as sugar, molasses and rice, corn and
potato starches.
 Asphalt/bitumen can also be made from waste material by
fractional distillation of used motor oils, which is sometimes
disposed by burning or dumping into landfills.

Modern Use
52
 Nonpetroleum-based asphalt/bitumen binders can be made light-
colored. Lighter-colored roads absorb less heat from solar radiation,
and have less surface heat than darker surfaces, reducing their
contribution to the urban heat island effect.

Wood
53
 Wood is a product of trees, and sometimes other
fibrous plants, used for construction purposes
when cut or pressed into lumber and timber, such
as boards, planks and similar materials.
 Wood can be very flexible under loads, keeping
strength while bending, and is incredibly strong
when compressed vertically.

Metal
54
 Metal is used as structural framework for larger buildings such as
skyscrapers, or as an external surface covering.
 Corrosion is metal's prime enemy when it comes to longevity.
 There are many types of metals used for building.
 Steel is strong, flexible, and if refined well and/or treated lasts a long
time.
 Aluminium and tin have a lower density and better corrosion resistance.
 Brass was more common in the past, but is usually restricted to specific
uses or specialty items today.
 Titanium can be used for structural purposes, but it is much more
expensive than steel.
 Chrome, gold, and silver are used as decoration, because these materials
are expensive and lack structural qualities such as tensile strength or
hardness.

Glass
55
 The use of glass in architectural buildings has
become very popular in the modern culture. Glass
"curtain walls" can be used to cover the entire
facade of a building, or it can be used to span over
a wide roof structure in a "space frame".
 These uses though require some sort of frame to
hold sections of glass together, as glass by its self
is too brittle and would require an overly large kiln
to be used to span such large areas by itself.

Fabric
56
 A major construction technique with the
development of tensile architecture and synthetic
fabrics.
 Modern buildings can be made of flexible material
such as fabric membranes, and supported by a
system of steel cables, rigid framework or internal
(air pressure.)

Unit 1.civil engineering materials

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Unit 1.civil engineering materials