UNIT I

BUILDING MATERIALS
IMPORTANT TOPICS
Building stones, rocks and
quarrying.
Quarrying tools
Building Materials, Construction
and Planning

Topic: Bricks
 Qualities of Good Brick
• Bricks should be table moulded, well burnt in kilns, copper
coloured, free from cracks and with sharp and square edges.
• Bricks should be uniform shape and should be of standard size.
• Bricks should give clear ringing sound when struck each other.
• Bricks when broken should show a bright homogeneous and
compact structure free from voids.
• Bricks should not absorb water more than 20 percent by weight
for first class bricks and 22 percent by weight for second class
bricks, when soaked in coldwater for a period of 24 hours.
• Bricks should be sufficiently hard no impression, should be left
on brick surface, when it is scratched with finger nail.
• Bricks should be low thermal conductivity and they should be
sound proof.
 Cont..
• Bricks should not break when dropped flat on hard ground
from a height of about one meter.
• Bricks, when soaked in water for 24hours, should not show
deposits of white salts when allowed to dry in shade.
• No brick should have crushing strength below 55kg/cm2
 Tests for Bricks

A brick is generally subjected to following tests to find out its

suitability of the construction work.
i. Absorption
ii. Crushing strength or compression strength
iii. Hardness
iv. Presence of soluble salts
v. Shape and size
vi. Soundness
vii. Structure
Cont..
1) Absorption: A good should not absorb not more than 20 percent of weight
of dry brick.
2) Compressive strength: crushing or compressive strength of brick is found
out by placing it in compression testing machine. It is pressed till it breaks.
Minimum crushing strength of brick is35kg/cm2 and for superior bricks, it
may vary from 70 to 140 kg/cm2.
3) Hardness: No impression is left on the surface the brick is treated to be
sufficiently hard.
4) Presence of soluble salts: The bricks should not show any grey or white
deposits after immersed in water for 24 hours.
5) Shape and size: It should be standard size and shape with sharp edges.
6) Soundness: The brick should give clear ringing sound struck each other.
7) Structure: The structure should be homogeneous, compact and free from
any defects.
 Classification of Bricks
Bricks can broadly be divided into two categories.
(i) Unburnt or sundried bricks
(ii) Burnt bricks.

• Un burnt or Sun dried bricks- Unburn or sun dried with the

help of heat received from sun after the process of moulding.
These bricks can only be used in the constructions of
temporary and cheap structures. Such bricks should not be
used at places exposed to heavy rains.
Cont..
• Burnt Bricks: The bricks used in construction works are
burnt bricks and they are classified into the following four
categories.
a. First class bricks: These bricks are table moulded and of
standard shape. The surface and edges of the bricks are sharp,
square, smooth and straight. The comply all the qualities of
good bricks and used for superior work of permanent nature.
b. Second class bricks: These bricks are ground moulded and
they are burnt in kilns. The surface of bricks is somewhat
rough and shape is also slightly irregular. These bricks are
commonly used at places where brick work is to be provided
with a coat of plaster.
Cont..
c. Third class bricks: These bricks are ground moulded and they
burnt in clamps. These bricks are not hard and they have rough
surfaces with irregular and distorted edges. These bricks give
dull sound when struck together. They are used for
unimportant and temporary structures and at places where
rainfall is not heavy.
d. Fourth class bricks: These are over burnt bricks with
irregular shape and dark colour. These bricks are used as
aggregate for concrete in foundation, floors, roads, etc because
of the fact that the over burnt bricks have compacted structure
and hence, they are some times found stronger than even first
class bricks.
Grading of Bricks
As per IS10719557 and 1970 code specifications,
• Bricks with compressive strength not less than 140kg/cm2 –
Grade A-A class.
• Bricks with compressive strength not less than 105kg/cm2 –
First class bricks - Grade A.
• Bricks with compressive strength not less than 70kg/cm2 –
Second class bricks – Grade B.
• Bricks with compressive strength not less than the average
value 35kg/cm2 – class III bricks – Grade C.
a. Squint Bricks: These bricks are made in a variety of shapes
and are used to the construction of a cute and obtuse squint
quoins as shown in the fig.
 Special Types
Bricks are made in a wide range of shapes and to suit the
requirements of the location where they are to be used. Special
form of bricks may be needed due to structural consideration
or for ornamental decoration as defined by the architect.
Specially moulded bricks avoid the cumbersome process of
cutting and rounding the rectangular bricks to the desired
shape.

• Some of the special types of bricks commonly used are given

below.
e. Circular Bricks: These bricks have internal and external faces
curved to meet the requirement of the particular curve and
radius of the wall. These bricks are used for wells, towers etc
f. Plinth cornice and String Course Brick: These bricks are moulded in
several patterns with the object of adding architectural beauty to the
structure and at the same time to helping to throw the rack water off the
face of the walls.
g. Coping Bricks: These bricks are manufactured in a variety of
shapes to set the thickness of the wall and are throated on the
underside to throw off rain water as shown in the fig. below
h. Paving Bricks: These bricks are specially made for paving the surface of
streets and highways. These bricks are usually made from shale, fire clay
on a mixture of the two. They are unaffected by weather and ordinary
traffic wear. They are loaded on the bed of sand which in term rests on
foundation of stone or concrete. The bricks are laid by grouting with
cement mortar or asphalt. They are machine moulded and are burnt in a
continuous kiln to ensure high degree of vitrification.
b. Bull Nosed Bricks: These bricks are used to form rounded
quoins.
c. Perforated Bricks: These bricks may be standard size bricks
produced with perforations running through their thickness.
Perforated bricks are easy to burn and their light weight makes
it possible to cut down the weight of the structure and effect in
foundations. The aperture of the perforations is such that it
gives maximum amount of ventilation. But does not permit the
entry of rats or mice. These bricks are used for constructing
load bearing walls of low buildings, panel walls for
multistoried buildings and for providing partition walls.
d. Hallow Bricks: These bricks are made of clay and are
provided with one or more cavities. Hallow bricks are light in
weight and are used to increase insulation against heat and
dampness. They are used for the construction of load bearing
walls, partition walls or panel walls to multistoried buildings.
Building Materials, Construction
and Planning

Topic: “TIMBER”
 Introduction
• Trees are the tallest living things and the man chops down
forests without replanting for tomorrow. The forests are vital
for economic property of land. The man and trees are closely
linked and without trees, the life on our planet would be
endangered.
• Timber denotes wood, which is suitable for building or
carpentry or various other engineering purposes like for
construction of doors, windows, roofs, partitions, beams,
posts, cupboards, shelves etc.,
 Uses of Timber
• Used in the form of piles, posts, beams, lintels, door/window
frames and leaves, roof members etc.,
• Used for flooring, ceiling, paneling and construction of
partition walls.
• Used for form work for concrete, for the timbering of trenches,
centering for arch work, scaffolding, transmission poles and
fencing.
• Used in wagon and coach building, marine installations and
bridges.
• Used in making furniture of agriculture implements, sports
goods, musical instruments, well curbs, mortar bodies, carts
and carriages, railway sleeps, packing cases etc..
 Classification of Trees
Depending upon their mode of growth, trees may be divided in
the following two categories.

• Endogeneous Trees: These trees grow inwards and fibrous

mass is seen in their longitudinal sections. Timber from these
trees has very limited engineering applications.
Ex: bamboo, cane , palm etc..
• Exogeneous Trees: These increases in bulk by growing
outwards and used for engineering purposes.
 Cont..
• Exogeneous trees are further sub divided into two groups
a) Conifers b) Deciduous

a) Conifers or evergreen trees: These trees having pointed,

needle like or scale like leaves and yield soft wood

b) Deciduous trees: The trees having flat broad leaves and leaves
of those trees fall in autumn and new ones appear in spring
season. Timber for engineering purpose is mostly derived from
deciduous trees. These tree yield hardwood.
Ex: ash, beach, oak, sal, teak, shishum and wallnut.
Comparison of softwood and hard wood
S.No. Item Soft wood Hard wood

1 Annual rings Distinct Indistinct

2 Colour Light Dark

3 Fire resistance Poor More

4 Modullary rays Indistinct Distinct

5 Structure Resinous and split Non-resinous & Close

easily grained
6 Weight Light Heavy

7 Strength Strong for direct pull & Equally strong for

weak for resisting thrust resisting tension,
or shear compression & shear
 Structure of tree
From the visibility aspect, the structure of a tree can be divided
into two categories
1. Macro structure
2. Micro structure

• Macro structure: The structure of wood visible to the naked

eye or at a small magnification is called macro structure. Fig
below shows the macro structure of exogenous tree.
Structure of Exogeneous Tree
• Pith: The innermost central portion or core of the tree is called pith
or medulla.
• Heart wood: The inner annual rings surrounding the pith is known
as heart wood. It imparts rigidity to tree.
• Sap wood: The cuter annual rings between heart wood and
cambium layer is known as sap wood.
• Cambium layer: Thin layer of sap between sap wood and inner
bark is known as cambium layer.
• Inner bark: The inner skin or layer covering the cambium layer is
known as inner bark.
• Outer Bark: The outer skin or cover of the tree is known as outer
bark.
• Medullary rays: The thin radial fibres extending from pith to
cambium layer are known as medullary rays.
• Micro structure: The structure of wood apparent
only at great magnifications is called micro structure
under micro scope, it becomes evident that the wood
consists of living and lead cells of various sizes and
shapes.
 Felling of Timber

Following are the four stages for the processing of

timber:
• Felling of trees
• Seasoning of timber
• Conversion of timber
• Preservation of timber
(a)Felling of trees: To get timber, the trees are knocked down or
cut down or caused to fall to the ground. This is known as the
felling of trees. The important facts to be remembered in
connection with felling of trees are as follows:
(i) Age of trees: For felling the trees should be felled when they
have just matured or when they are very near to maturity.
The age of good trees for felling varies from 50 to 100 years.
(ii) Method of felling: the trees should be felled by experienced
persons. The trees should be cut from a place a little above
its roots and very near to the ground level. Such practice
would help in getting more timber from the trunk of tree.
(iii) Season for felling: The trees should be felled when sap is at
rest. The season for felling of trees should be carefully
determined by keeping in mind the climatic conditions of the
locality and types of trees.
(b)Seasoning of timber: When a tree is newly felled, it contains about
50% or more of its own dry weight as water. This water is in the form
of sap & moisture. The water is to be removed before the timber can
be used for any engineering purpose. In other words, the timber is to
be dried. This process of drying of timber is known as the Seasoning
of timber and the moisture should be extracted during seasoning under
controlled conditions as nearly as possible at a uniform rate from all
parts of the timber.
Important terminologies:
• The capacity of wood to absorb water vapours from air is called the
“Hygroscopicity of wood”.
• The moisture in timber which are present in cell cavities are known as
“Free Moisture”.
• The moisture in timber which are present in cell walls are known as
“Bound moisture”.
• The moisture content of timber is determined by
P = (W1-W2)/W2 x 100
 Objectives of seasoning
• To allow timber to burn readily, if used as fuel.
• To decrease the weight of timber & thereby to lower the cost of transport
and handling.
• To impart hardness, stiffness, strength & better electrical resistance to
timber.
• To increase the resisting power of timber, as most of the causes of decay
of timber are more or less related to the moisture.
• To maintain the shape & size of the components of the timber articles
which are expected to remain unchanged in form.
• To make timber fit for receiving treatment of paints, preservatives,
varnishes, etc.
• To make timber safe from the attack of fungi & insects.
• To reduce the tendency of timber to crack, shrink and warp.
 Method of Seasoning
It can be divided into following categories:
(i) Natural Seasoning
(ii) Artificial Seasoning.
• Natural Seasoning: It may be air seasoning or water seasoning. Air
seasoning is carried out in a shed with a platform. On about 300 mm
high platform timber balks are stacked.
• Care is taken to see that there is proper air circulation around each
timber balk. Over a period, in a natural process moisture content
reduces. A well seasoned timber contains only 15% moisture. This is a
slow but a good process of seasoning.
• Water seasoning is carried out on the banks of rivers. The thicker end of
the timber is kept pointing upstream side. After a period of 2 to 4 weeks
the timber is taken out. During this period sap contained in the timber is
washed out to a great extent. Then timber is stalked in a shed with free
air circulation.
• Artificial Seasoning: In this method timber is seasoned in a
chamber with regulated heat, controlled humidity and proper
air circulation. Seasoning can be completed in 4 to 5 days
only. The different methods of seasoning are:
(a) Boiling
(b) Kiln seasoning
(c) Chemical seasoning
(d) Electrical seasoning.
(a) Boiling: In this method timber is immersed in water and then
water is boiled for 3 to 4 hours.
Then it is dried slowly. Instead of boiling water hot steam
may be circulated on timber. The process of
seasoning is fast, but costly.
Boiling Seasoning
(b) Kiln Seasoning: Kiln is an airtight chamber. Timber to be seasoned is placed inside
it. Then fully saturated air with a temperature 35°C to 38°C is forced in the kiln.
The heat gradually reaches inside timber. Then relative humidity is gradually
reduced and temperature is increased, and maintained till desired degree of
moisture content is achieved.
The kiln used may be stationary or progressive. In progressive kiln the carriages
carrying timber travel from one end of kiln to other end gradually. The hot air is
supplied from the discharging end so that temperature increase is gradual from
charging end to discharging end. This method is used for seasoning on a larger
scale.
(c) Chemical Seasoning: In this method, the timber is immersed in a solution of
suitable salt. Then the timber is dried in a kiln. The preliminary treatment by
chemical seasoning ensures uniform seasoning of outer and inner parts of timber.
(d) Electrical Seasoning: In this method high frequency alternate electric current is
passed through timber. Resistance to electric current is low when moisture content
in timber is high. As moisture content reduces - the resistance reduces. Measure of
resistance can be used to stop seasoning at appropriate level.
Kiln Seasoning
Chemical Seasoning
Electrical Seasoning
 Conversion of timber
• The process by which timber is cut and sawn into suitable
sections is known as the conversion. For this process, the
power machines may be employed at different stages of
process.
 Preservation of timber
Preservation of timber means protecting timber from fungi and insects attack
so that its life is increased. Timber is to be seasoned well before application
of preservatives. The following are the widely used preservatives:
1. Tar
2. Paints
3. Chemical salt
4. Creosote
5. ASCO
1. Tar: Hot coal tar is applied to timber with brush. The coating of tar protects
the timber from the attack of fungi and insects. It is a cheapest way of
protecting timber. Main disadvantage of this method of preservation is that
appearance is not good after tar is applied it is not possible to apply other
attractive paints. Hence tarring is made only for the unimportant structures
like fence poles.
2. Paints: Two to three coats of oil paints are applied on clean surface of wood. The paint protects
the timber from moisture. The paint is to be applied from time to time. Paint improves the
appearance of the timber. Solignum paint is a special paint which protects the timber from the
attack of termites.

3. Chemical salt: These are the preservatives made by dissolving salts in water. The salts used are
copper sulphate, masonry chloride, zinc chloride and sodium fluoride. After treating the
timber with these chemical salt paints and varnishes can be applied to get good appearance.

4. Creosote: Creosote oil is obtained by distillation of coal tar. The seasoned timber is kept in an
air tight chamber and air is exhausted. Then creosote oil is pumped into the chamber at a
pressure of 0.8 to 1.0 N/mm2 at a temperature of 50°C. After 1 to 2 hours timber is taken out
of the chamber.

5. ASCO: This preservative is developed by the Forest Research Institute, Dehradun. It consists of
1 part by weight of hydrated arsenic pentoxide (As2O5, 2 H2O), 3 parts by weight of copper
sulphate (CuSO4⋅5 H2O) and 4 parts by weight of potassium dichromate (K2Cr2O7) or
sodium dichromate (Na2Cr2O7⋅2 H2O). This preservative is available in powder form. By
mixing six parts of this powder with 100 parts of water, the solution is prepared. The solution
is then sprayed over the surface of timber.
This treatment prevents attack from termites. The surface may be painted to get desired
appearance.
 Methods for preservation

Following are the six methods adopted for preserving of timber

• Brusing
• Charring
• Dipping & steeping
• Hot & cold open tank treatment
• Injecting under pressure
• Spreying
 Defects in Timber
Defects occurring in timber are grouped into the following
divisions.
a) Defects due to conversion: During the process of converting
timber to commercial form, the following defects may occur.
(i) Chip mark: mark or sign placed by chip on finished surface
of timber.
(ii) Diagonal grain: Due to improper sawing of timber.
(iii)Torn grain: Due to falling of tool small impression is
formed.
(iv)Wane: Presence of original rounded surface on the
manufactured piece of timber.
Cont..
b)Defects due to fungi: The attack of timber by fungi when moisture content of
timber is above 20% and presence of air and warmth for the growth of fungi
the following defects are caused.

(i) Blue stain: Sap of wood is stained to bluesh colour.

(ii)Brown rot: Decay or disease of timber by removal of cellulose compounds
from wood and wood assumes the brown colour.
(iii)Dry rot: Convert the wood into dry powder form.
(iv)Heart rot: This is formed when branch has come out of a tree and the tree
becomes weak and gives out hallow sound when struck with a hammer.
(v)Sap stain: The sap wood looses its colour because of feed on cell contents of
sap wood.
(vi)Wet rot: Caused chemical decomposition of wood of the timber and timber
converts to grayish brown powder known as wet rot.
(vii)White rot: Attack lignin of wood and wood assumes the appearance of
white mass.
c) Defects due to insects:
(i) Beetles: Small insects form holes of size about 2mm
diameter and attack sap wood of all spacies of hard woods.
Tunnels are formed in all directions in sapwood by the
larvae of these beetles and converted into fine flour like
powder. They do not disturb outer cover and looks sound.
(ii) Marine borers: These make holes or bore tunnels in wood
for taking shelter. The wood attacked by marine borers loses
colour and strength.
(ii) Termites: White ants are very fast in eating away the wood
from the core of the cross section. They make tunnels inside in
different directions and usually do not disturb the outer shell
or cover.
d) Defects due to natural forces:
The main natural forces responsible for causing defects in timber
are abnormal growth and rapture of tissues.
(i)Burls: Irregular projections appear on the body of timber
because of shock at younger age.
(ii)Callus: Soft tissue or skin which covers the wound of tree.
(iii)Chemical stain: Discoloured due to the chemical action
caused.
(iv)Coarse grain: Annual rings are widened, tree grows rapidly
hence timber possesses less strength.
(v)Dead wood: Timber obtained from dead standing tree.
(vi)Druxiness: White decayed spots by fungi.
(vii)Foxiness: Due to poor ventilation during storage or by
commencement of decay due to over maturity indicated by red
or yellow tinge in wood.
(viii) Knots: Bases of branches or limbs which are
broken or cut off from the tree as shown in the fig
below.

(ix) Rind galls: Rind means bark and gall indicates

abnormal growth and pecullar curved swellings
found on the body of a tree.
(x) Shakes: These are cracks which partly or completely
separate the fibres of wood as shown in fig. below.
(xi) Twisted fibres: or Wandering hearts: caused by twisting
of young trees by fast blowing wind as shown in fig. below.

(xii) Upsets or ruptures: Indicate wood fibres which are

injured by crushing or compression as shown in fig. below
Different types of shakes
(xii) Upsets or ruptures: Indicate wood fibres which are injured
by crushing or compression as shown in fig. below
 Characteristics of good timbers
1. Appearance: A freshly cut surface of timber should exhibit
hard and of shining appearance.
2. Colour: A colour should preferably be dark.
3. Defects: A good timber should be free from series defects such
as knots, flaws, shakes etc..
4. Durability: A good timber should be durable and capable of
resisting the action of fungi, insects, chemicals, physical
agencies, and mechanical agencies.
5. Elasticity: The timber returns to its original shape when load
causing its deformation is removed.
6. Fibres: The timber should have straight fibres.
7. Fire resistance: A dense wood offers good resistance to fire
8. Hardness: A good timber should be hard.
9.Mechanical wear: A good timber should not deteriorate easily due to mechanical
wear or abrasion.
10.Shape: A good timber should be capable of retaining its shape during conversion or
seasoning.
11. Smell: A good timber should have sweet smell. Unpleasant smell indicates decayed
timber.
12. Sound : A good timber should give a clear ringing sound when struck.
13. Strength: A good timber should be sufficiently strong for working as structural
member such as joist, beam, rafter etc.
14. Structure: The structure should be uniform.
15. Toughness: A good timber should be tough (i.e.) capable of offering resistance to
shocks due to vibration.
16. Water permeability: A good timber should have low water permeability, which is
measured by the quantity of water filtered through unit surface area of specimen of
wood.
17. Weathering effects: A good timber should be able to stand reasonably the
weathering effects (dry & wet).
18. Weight: The timber with heavy weight is considered to be sound and strong.
19. Working conditions: Timber should be easily workable. It should not clog the
teeth of saw.
Tiles:

•A tile is a special type of brick which is often

larger than an ordinary brick.
•Tiles are mostly used for roofing and paving
purposes.
CLASSIFICATION OF
TILES:
 Tiles are classified into groups on the basis
of construction material.
(1) Material basis
(i) Common tiles
(ii) Encaustic tiles
 Depending upon their Use
(1) Roofing Tiles
(a) Plain Tiles
(b) Pot Tiles
(c) Allahabad Tiles
(d) Mangalore Tiles
(e) Concrete Roofing Tiles

(2) Flooring/Paving Tiles

(3) Drain Tiles
(i) Common tiles:
Common tiles may be used for roofing.
Flooring and walling also. Common tiles are
pan tiles, pot tiles and flat tiles.
(ii) Encaustic Tiles:
These tiles are prepared by mixing colors
with the clay before burning. These are used
for decorative purposes.
(1) CLASSIFICATION
OF
TILES
BASED UPON
MATERIAL
USED
(2) CLASSIFICATION
OF
TILES
BASED UPON
THEIR USE
 (i) Roofing tiles:
These may be flat like slates or
may be made to different shapes.
Some of the common varieties
are discussed below.
 (a) Plain tiles:
The size of these tiles is 25 cm x 15
cm to 28 cm x 18 cm and
thickness varies from 10 mm to 17
mm.
(b) Pan tiles:
These tiles are curved in section.
These are 33 cm to 38 cm long and
23 cm to 28 cm wide
 (c) Pot tiles:
These are semi circular in
section and taper along the
length. The diameter at larger
end is about 23 cm
and at the smaller end it
is about 20 cm.
 (d) Allahabad
These consist of two tiles:
sets of tiles. The lower
ones are flat tiles with upturned sides. End
widths reduce from 27 cm to 23 cm and the
length is about 38 cm. The over tile is half
round in section and tapers from 16.5 cm to 12
cm in diameter. Half round tiles are moulded
on a potters’ wheel as a round tapering
cylindrical tile. Two longitudinal cuts are given
to the cylinder while still not dry. With this it
is easy to break it into two semicircular tiles
after burning.
(e) Mangalore tiles:
These are flat pattern tiles
with suitable key projection.
About 16 tiles are required
to cover one square meter of
roof.
(f) Concrete roofing tiles:
Tiles of any shape, size or
colour could be made with
cement concrete. These are
more strong, durable and
weather resistant.
 (2) Flooring or Paving tiles:
These are usually thicker than roofing tiles and
vary from 15 mm to 30 mm in thickness. Their
shapes are square, hexagonal or any of other
geometrical pattern and may be coloured, if
desired.
Depending upon properties of clay flooring tiles
are classified as: class 1, class 2, class 3 tiles.
Maximum water absorption percentages in
case of these tiles are 10, 19 and 24
respectively.
(3) Drain tiles:
These are curved tiles made in
various shapes and sizes to suit the
work in which they are to be
used. Tiles to be used in the
construction
of sewage carrying drains should
be glazed.
MANUFACTURING
OF
TILES
MANUFACTURING OF TILES:
Six main operations are involved in
the manufacturing of tiles:
1. Selection of suitable clay
2. Preparation of clay
3. Moulding
4. Drying and Shaping
5. Burning
6. Cooling
(1) Selection of suitable
clay: For manufacturing of
tiles, we require
superior type of clay. The
clay should be completely
free from grit, pebbles
and other organic matter.
(2) Preparation of clay:
This is done by mixing water with
clay in a tank and storing it in damp
condition. The solution is then
allowed to stand quietly in the tank
resulting in the setting and leaving
of coarse particles. Water containing
fine clay in solution is rained off to
other tanks where it is allowed to
dry leaving fine clay ready for
moulding.
(3) Moulding:
Moulding operation is done on the ground
specially prepared for that purpose. All the
instruments which are used in the moulding
should be present.
The moulder sprinkles ashes over the clay
and start to mould according to the required
size of tiles on the smooth and leveled
surface, when the number of 10 to 15 tiles
are prepared they are taken for drying and
shaping.
 (4) Drying and Shaping:
Two days after moulding, the
tiles are given proper shape and
then they are placed on their
edges and dried for about two
days. One thing should be kept
in mind that we take care to
crack and wrap and they should
be dried slowly.
(5) Burning:
Tiles are burnt in a kiln which is in
circular shape. Tiles are kept on their
edges and door ways are closed with
bricks. The maximum temperature of tiles
should be 2200degreeF for about three
hours. This process is repeated for second
time.
The kiln is isolated after it has cooled
down. The kiln should be protected
against bad weather specially on the wind
side by temporary roofing.
 (6) Cooling:
After burning, cooling is done for 3 to
5 days.
(OR)
3 to 5 days are required for cooling of
tiles.
 GLASS
AND
ITS
MANUFACTURING
 GLAS
S
Glass is obtained by fusion of silica,
chalk (lime) and potash or soda at over
10000C.In order to modify its properties
of hardness, brittleness and
colour ,other ingredients like iron oxide,
lead oxide,borax,etc are added in
varying proportions.
Functions of various important
constituents of glass are given below.
(1) Silica (SiO 2 ):
It is the major constituent of all types of
glass. As it fuses at very high
temperatures some alkaline admixtures
like sodium carbonate or potassium
carbonate is added to it so as to make
it fuse at lower temperature. The
admixtures added to lower the fusion
temperature also make the liquid silica
viscous and better workable.
(2) Potash:
It renders glass infusible and
gives fire resisting properties to
it. (3) Soda:
It accelerates fusion of glass;
as such excess of it is
harmful.
(4) Lime (CaO):
It gives durability and
toughness (hardness) to glass.
(5) Lead oxide:
It gives colour to
glass. (6) Cullet:
It is broken glass, which is used as
a raw material to reduce to its
cost.
SPECIAL
COMMERCIAL FORMS
OF GLASS:
For various engineering and
industrial requirements special
varieties of glass with the
desired specifications are
made. These include the
following:
(1) Sheet Glass:
Sheet glass is made by blowing.
It is available within 2 to 6 mm
thicknesses.
It is mainly used as door and
window panels and for all kinds
of glazing works.
(2) Plate Glass:
Molten glass is rolled into plate
glass with thicknesses varying
from 6 to 25mm. It is also suitable
for glazing works, as table tops,
windows, train carriages, buses,
cars, the windscreens and superior
quality mirrors.
(3) Coloured Glass:
It is prepared by mixing different
pigments at the fusion stage. It
diffuses the light passing
through it. It is also called as
stained glass.
It is used in decorative works.
(4) Wired Glass:
This is the plate and sheet glass in
which steel wires or mesh is
embedded during the rolling
process. The steel wire acts as
reinforcement. It is also called as
reinforced glass.
It is used for sky-lights, high
class roofing works and fire
proof doors and windows.
(5) Structural Glass:
This type of glass is used in constructional
works and can be embedded anywhere
within the walls and ceilings. It is made in the
form of hollow square blocks, tiles, bricks
and lenses. It is light in weight. It can be
easily cut and drilled.
It is used for transparent face work, partition
walls, roofing and flooring works where ever
light is desired to pass through. It is also
used for heat and sound insulation works.
(6) Laminated Glass:
This is also safety glass; it
consists of sheets of glass
glued together with a celluloid
layer between them.
It is used for the wind screens
and rear glass in the automobiles
etc.
(8) Fibre Glass:
This is also described as glass
wool; it is in the form of glass
fibres which are soft and
flexible. It is highly resistant to
wear and tear.
It is mainly used for all kinds
of thermal and sound
insulation works.
(10) Flint Glass:
It is the glass containing lead which
makes it highly shining and capable of
high polish. It is costly glass. It is also
known as shielding glass as it stops
different kinds of radiations. It is widely
used for high-class glass ware like cut
glass, table glass, as optical glass for
lenses, prisms and slabs, electric
bulbs, electric tubes, radio valves, etc.
(11) Soluble Glass:
It is that type of glass which is
soluble in water. It may be
kept in the form of small chips or
pieces or in liquid glass. It is
prepared by melting a mixture of
silica and sodium sulphate or
potassium carbonate.
The soluble glass is used for mixing
with cement to make it resistant to
the acids.
PROPERTIES (OR) CHARACTERISTICS OF
GLASS:
(1)It has highly shining appearance and takes good
polish.
(2)It is not affected by temperature except in some
exceptional cases.
(3) It is fire retardant.
(4) It provides heat insulation.
(5) It also ensures transmission of light.
(6) It is available in various varieties.
(7)It transmits light but also provide privacy by
obstructing vision.
(8)Glass blocks provide heat and sound proof
properties.
 USES OF
(1)Glass is extensively usedGLASS:
in building construction
since long time for glazing doors and windows.
(2) It is also used for decoration.
(3) It is also used for sound insulation purposes.
(4)It is used for cut glass work, electric bulbs (lead
glass).
(5)It is used for manufacturing of laboratory
equipments and cooking utensils (Boro-silicate
glass).
(6) It is used for partition walls.
(7) It is used for cabinets, show cases, shop
fronts.
(8) It is also used as fire retarder.
REINFORCED STEEL BARS:
As plain cement concrete (PCC) is strong in compression
but very weak in tension and shear. As mild steel bars are
strong in tension. Therefore, mild steel bars or high carbon
steel bars are embedded as reinforcement in the concrete
to make good that deficiency of the plain concrete.
Therefore, round, flat or square bars too can be used for
that purpose.
Welded wire mesh and expanded metal too are used as
reinforcement in cement concrete.
Commonly deformed bars or twisted bars are used in cement
concrete.
Therefore, RCC sections will carry compression as well as
tension safely without failure.
In these sections compression will be taken by concrete and
tension by steel.
 NON-
FERROUS
METALS
(1) ALUMINUM:
It is more commonly used non-ferrous metal. It is widely
used in every field of Engineering. Due to improved strength
and durability, aluminum is a versatile material for use by
Engineers.
Properties and Uses:
(1) Its colour is silvery white.
(2) It shows bright luster on a freshly broken surface.
(3) It is ductile material,
(4) It is very light in weight.
(5) It also resists atmospheric corrosion,
(6) It is very good conductor of electricity,
(7) It is used for making door and window frames,
(8) It is also used in roofing, piping, etc,
(9) It is also used in electric wires, cables.
 It is one of the most widely used
non-ferrous metals. It is not widely
used in
•Properties:
Engineering due to its high
cost.
(1) It is crystalline in structure,
(2) Its color is reddish brown,
(3) It is highly ductile,
(4) It is excellent conductor of electricity,
(5) When exposed to sun, its colour turns
greenish,
• Continued------
(6) It with stands corrosion,
(7) It is soft and highly flexible,
(8) It is light in weight,
(9) Dents in copper can be hammered
out without any damage to it.
Uses:
(10) It is used for winding electric motors,
generators and for transmission of electricity,
(11)Its sheets are used as damp proofing
in buildings.
(3) LEAD:
It is widely used in building construction and has draw
back of being poisonous.
Properties:
(1) It is bluish grey metal,
(2) It is soft as it can be cut with a knife,
(3) It is highly ductile,
(4) It is a good conductor of heat and electricity,
(5) It does not corrode,
(6) Its specific gravity is 11.35.
Uses:
(7) It is used as a base in paints,
(8) Lead pipes and lead joints in sanitary fittings
are extensively used.
(4) TIN:
It is one of the mostly used protective metals
used in construction activities.
Properties:
(1) It is lustrous silvery white metal,
(2) It is highly ductile,
(3) It is a good conductor of heat and
electricity,
(4) It is soft and has good plasticity,
(5) Its specific gravity is 7.3.
Uses:
It is used to give protective coatings to iron and
steel sheets.
(5) ZINC:
It is commonly used in building construction either as a
base for paints or as protective coverings for metals.
Properties:
(1) It is bluish white crystalline metal,
(2) It is brittle metal at ordinary temperature,
(3) It becomes ductile between 100-1500C,
(4) It is a good conductor of heat and electricity,
(5) It resists corrosion.
Uses:
(6) It is used for galvanizing iron sheets and pipes,
for batteries and printing blocks,
(7) It is also used for preparing paints.
NON-
FERROUS
ALLOYS
(1) BRASS:
Brass is an alloy of about 60-70 % copper and
zinc. Hardness of this alloy depends upon the
amount of zinc present in it.
Properties:
(1) It is very strong,
(2) It is ductile alloy,
(3)It resists corrosion,
Uses:
It is widely used for making house hold utensils,
water pumps and other machine parts.
(2) BRONZE:
Bronze is an alloy of 90 % copper and 10 % tin. It
can be easily machined and cast.
Properties:
*It resists corrosion.
*It takes a fine polish.
Uses:
(1) It is used for manufacturing of house hold
utensils.
(2) Phosphorous bronze is used for making
radio aerials and certain other instruments.