Materials & Methods of Construction - CE145

1 | P a g e
SAQIB IMRAN 0341-7549889 1

2 | P a g e
SAQIB IMRAN 0341-7549889 2
Materials & Methods of Construction - CE145
Chapter No 1
Bricks
Brick is obtained by moulding good clay into a block, which is dried and then burnt. This is the
oldest building block to replace stone. Manufacture of brick started with hand moulding, sun
drying and burning in clamps. A considerable amount of technological development has taken
place with better knowledge about to properties of raw materials, better machinaries and
improved techniques of moulding drying and burning.
The size of the bricks are of 90 mm × 90 mm × 90 mm and 190 mm × 90 mm × 40 mm. With
mortar joints, the size of these bricks are taken as 200 mm × 100 mm × 100 mm and 200 mm ×
100 mm × 50 mm. However, the old size of 8
3"
4
x 4
1
2
x 2
5"
8
giving a masonry size of 9” x 4
1
2
x 3”
is still commonly used in india.
Types of Bricks – Detail Classification of Bricks
Bricks are a regular size rectangular unit. Bricks are made of clay. They are usually used for most
of the building works. Bricks are most generally used as a substitute for stone when the stone is
not available.
Types of Bricks
Bricks can be of many types depending on –
1. Quality
2. Building Process

3 | P a g e
SAQIB IMRAN 0341-7549889 3
3. Manufacturing Method
4. Raw Material
5. Using Location
6. Weather-resisting Capability
7. Purpose of Using
8. Shape
9. Region
Classification of Bricks Based on Quality
On the basis of quality, Bricks are of the following kinds:
First Class Brick: The size is standard. The color of these bricks is uniform yellow or red. It is well
burnt, regular texture, uniform shape. The absorption capacity is less than 10%, crushing
strength is, 280kg/cm2 (mean) where it is 245 kg/cm2 (minimum). It doesn’t have
efflorescence. It emits a metallic sound when struck by another similar brick or struck by a
hammer. It is hard enough to resist any fingernail expression on the brick surface if one tries to
do with a thumbnail. It is free from pebbles, gravels or organic matters. It is generally used-
 in a building of long durability, say 100 years
 for building exposes to a corrosive environment;
 for making coarse aggregates of concrete.
Second Class Brick: The size is standard, color is uniform yellow or red. It is well burnt, slightly
over burnt is acceptable. It has regular shape; efflorescence is not appreciable. The absorption
capacity is more than 10% but less than 15%. Crushing strength is 175kg/cm2(mean) where the
minimum is 154 kg/cm2. It emits a metallic sound when struck by another similar brick or struck
by a hammer. It is hard enough to resist any fingernail expression on the brick surface if one
tries to do with a thumbnail. It is used for the construction of one-storied buildings, temporary
shed when intended durability is not more than 15 years.
Third Class Brick: The shape and size are not regular. The color is soft and light red colored. It is
under burnt, slightly over burnt is acceptable. It has extensive efflorescence. The texture is non-
uniform. The absorption capacity is more than 15% but less than 20%. The crushing strength is
140kg/cm2(mean) where the minimum crushing strength is 105kg/cm2. It emits a dull or blunt
sound when struck by another similar brick or struck by a hammer. It leaves fingernail
expression when one tries to do with the thumbnail.
Classification of Bricks Based on Building Process
On the basis of the building process Bricks are of following kinds:

4 | P a g e
SAQIB IMRAN 0341-7549889 4
1. Unburnt Bricks: These are half burnt bricks. The color is yellow. The strength is low.
They are used as surki in lime terracing. They are used as soiling under RCC footing or
basement. Such bricks should not be exposed to rainwater.
2. Burnt Bricks: Burnt bricks are made by burning them in the kiln. First class, Second Class,
Third Class bricks are burnt bricks.
3. Over Burnt or Jhama Brick: It is often known as the vitrified brick as it is fired at high
temperature and for a longer period of time than conventional bricks. As a result, the
shape is distorted. The absorption capacity is high. The strength is higher or equivalent
to first class bricks. It is used as lime concrete for the foundation. It is also used as
coarse aggregate in the concrete of slab and beam which will not come in contact with
water.
Classification of Bricks Based on Manufacturing Method
On the basis of manufacturing method bricks are of following kinds:
1. Extruded Brick: It is created by forcing clay and water into a steel die, with a very
regular shape and size, then cutting the resulting column into shorter units with wires
before firing. It is used in constructions with limited budgets. It has three or four holes
constituting up to 25% volume of the brick.
2. Molded Brick: It is shaped in molds by hand rather being in the machine. Molded bricks
between 50-65mm are available instantly. Other size and shapes are available in 6-8
weeks after the order.
3. Dry pressed Brick: It is the traditional types of bricks which are made by compressing
clay into molds. It has a deep frog in one bedding surface and shallow frog in another.
Classification of Bricks Based on Raw Materials
On the basis of raw materials bricks are of following kinds:
1. Burnt Clay Brick: It is obtained by pressing clay in molds and fried and dried in kilns. It is
the most used bricks. It requires plastering when used in construction works.
2. Fly ash clay Brick: It is manufactured when fly ash and clay are molded in 1000 degree
Celsius. It contains a high volume of calcium oxide in fly ash. That is why usually
described as self-cementing. It usually expands when coming into contact with
moisture. It is less porous than clay bricks. It proved smooth surface so it doesn’t need
plastering.
3. Concrete Brick: It is made of concrete. It is the least used bricks. It has low compression
strength and is of low quality. These bricks are used above and below the damp proof
course. These bricks are used can be used for facades, fences and internal brickworks
because of their sound reductions and heat resistance qualities. It is also
called mortar brick. It can be of different colors if the pigment is added during
manufacturing. It should not be used below ground.

5 | P a g e
SAQIB IMRAN 0341-7549889 5
4. Sand-lime Brick: Sand, fly ash and lime are mixed and molded under pressure. During
wet mixing, a chemical reaction takes place to bond the mixtures. Then they are placed
in the molds. The color is greyish as it offers something of an aesthetic view. It offers a
smoother finish and uniform appearance than the clay bricks. As a result, it also doesn’t
require plastering. It is used as load bearing members as it is immensely strong.
5. Firebrick: It is also known as refractory bricks. It is manufactured from special designed
earth. After burning, it can withstand very high temperature without affecting its shape,
size, and strength. It is used for the lining of chimney and furnaces where the usual
temperature is expected to be very high.
Classification of Bricks Based on Using Location
On the basis of using location bricks are of following kinds:
1. Facing Brick: The façade material of any building is known as facing brick. Facings bricks
are standard in size, are stronger than other bricks and also have better durability. The
color is red or brown shades to provide a more aesthetic look to the building. There are
many types of facing bricks which use different techniques and technology. Facing bricks
should be weather resistant as they are most generally used on the exterior wall of
buildings.
2. Backing Brick: These types of brick don’t have any special features. They are just used
behind the facing bricks to provide support.
Classification of Bricks Based on Weather-resisting Capability
On the basis of weather-resisting capability bricks are of following kinds:
1. Severe Weather Grade: These types of bricks are used in the countries which are
covered in snow most of the time of year. These bricks are resistant to any kind of
freeze-thaw actions.
2. Moderate Weather Grade: These types of bricks are used in the tropical countries. They
can withstand any high temperature.
3. No Weather Grade: These bricks do not have any weather resisting capabilities and
used on the inside walls.
Classification of Bricks Based on Their Using
There are many uses of bricks. On the basis of the purpose of their using bricks are of following
kinds:
1. Common Bricks: These bricks are the most common bricks used. They don’t have any
special features or requirements. They have low resistance, low quality, low
compressive strength. They are usually used on the interior walls.
2. Engineering Bricks: These bricks are known for many reasons. They have a high
compressive strength and low absorption capacity. They are very strong and dense.

6 | P a g e
SAQIB IMRAN 0341-7549889 6
They have good load bearing capacity, damp proof, and chemical resistance properties.
They have uniform red color. They are classified as Class A, class B, class C. Class A is the
strongest but Class B is most used. They are used for mainly civil engineering works like
sewers, manholes, ground works, retaining walls, damp proof courses etc.
Classification of Bricks Based on Shape
On the basis of shape bricks are of following kinds:
1. Bullnose Brick: These bricks are molded into round angles. They are used for rounded
quoin.
2. Airbricks: These bricks contain holes to circulate air. They are used in suspended floors
and cavity walls.
3. Channel Bricks: They are molded into the shape of a gutter or channel. They are used in
drains.
4. Coping Bricks: They can be half round, chamfered, Saddleback, angled varied according
to the thickness of the wall.
5. Cow Nose Bricks: Bricks having double bullnose known as Cow Nose Bricks.
6. Capping Bricks: These bricks are used to cap the tops of parapets or freestanding walls.
7. Brick Veneers: These bricks are thin and used for cladding.
8. Curved Sector Bricks: These are curved in shape. They are used in arcs, pavements etc.
9. Hollow Bricks: These bricks are around one-third of the weight of the normal bricks.
They are also called cellular or cavity bricks. Their thickness is from 20-25mm. These
bricks pave the way to quicker construction as they can be laid quickly compared to the
normal bricks. They are used in partitioning.
10. Paving Bricks: These bricks contain a good amount of iron. Iron vitrifies bricks at low
temperature. They are used in garden park floors, pavements. These bricks withstand
the abrasive action of traffic thus making the floor less slippery.
11. Perforated Bricks: These bricks contain cylindrical holes. They are very light in weight.
Their preparation method is also easy. They consume less clay than the other bricks.
They can be of different shapes like round, square, rectangular. They are used in the
construction of the panels for lightweight, structures, and multistoried frame
structures.
12. Purpose Made Bricks: For specific purposes, these bricks are made. Splay and can’t
bricks are made for doors and window jambs. Engineering bricks are made for civil
engineering constructions such as sewers, manholes, retaining walls. Fire bricks are
made for chimneys and fireworks. Ornamental bricks are made to use for cornices,
corbels. Arch bricks are used in arcs.
Classification of Bricks Based on Region
On the basis of the region bricks are of following kinds:
1. Cream City Bricks: These bricks are from Milwaukee, Wisconsin.

7 | P a g e
SAQIB IMRAN 0341-7549889 7
2. London Stock: These bricks are used in London.
3. Dutch: These are from the Netherlands.
4. Nanak Shahi Bricks: These are from India.
5. Roman: These are used in Roman constructions,
6. Staffordshire Blue Brick: These are from England.
Composition of a good brick earth:
Following are the constituents of a 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.
If alumina is present in excess with inadequate quantity of sand then the raw bricks shrink and
warp during drying, on burning they become too hard. So it is important to have an optimum
content of alumina.
(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.
The presence of this constituent prevents the shrinkage, cracking and warping of raw bricks. It
thus imparts uniform shape to the bricks. The durability of bricks depends upon proper
composition of silica in brick earth. The excess of silica destroys the cohesion b/w particles and
brick become brittle.
(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.
The lime prevents shrinkage of the raw bricks, sand alone is infusible, but it slightly fuses at kiln
temperature in presence of lime. Fused sand acts as a hard cementing material for brick
particles.
The excess of lime causes brick to melt and therefore its shape is lost. The lumps of lime turns
into quick lime (CaO) after burning and this free lime can later react with water to form slaked
lime. This process is called slaking it may result in splitting of the brick into pieces.
(4) Oxide of Iron (Fe2O3):

8 | P a g e
SAQIB IMRAN 0341-7549889 8
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.
Characteristics of Good Bricks
It is always desirable to use the best quality brick in constructions. Therefore, the Characteristics
of a good brick must be investigated. Generally good bricks possesses following properties-
 Bricks should be uniform in color, size and shape. Standard size of brick should be
maintained.
 They should be sound and compact.
 They should be free from cracks and other flaws such as air bubbles, stone nodules etc.
with sharp and square edges.
 Bricks should not absorb more than 1
⁄5 of their own weight of water when immersed in
water for 24 hours (15% to 20% of dry weight).
 The compressive strength of bricks should be in range of 2000 to 5000 psi (15 to 35
MPa).
 Salt attack hampers the durability of brick. The presence of excess soluble salts in brick
also causes efflorescence. The percentage of soluble salts (sulphates of calcium,
magnesium, sodium and potassium) should not exceed 2.5% in brunt bricks.
 Brick should not change in volume when wetted.
 Bricks should neither overburnt nor under-brunt.
 Generally, the weight per brick should be 6 lbs. and the unit weight should be less than
125 lbs. per cubic ft.
 The thermal conductivity of bricks should be low as it is desirable that the building built
with them should be cool in summer and warm in winter.
 Bricks should be sound proof.
 Bricks should be non-inflammable and incombustible.
 Bricks should be free from lime pitting.

9 | P a g e
SAQIB IMRAN 0341-7549889 9
Compressive Strength of Brick
Bricks are mainly used in the construction of wall, floor, cornices, and arches. Brick chips are
also used as a substitute for stone chips in the concrete mix where a stone is not available or an
economic solution is preferred. In all the above-mentioned cases, compression load governs. Due
to this, the compressive strength of bricks is a very important parameter.
Specified Compressive Strength
According to BDS 2002
Grade Mean Strength (kg/cm2 ) Minimum Strength (kg/cm2 )
S 280 245
A 175 154
B 140 105
According to Indian Standard (IS 1077:1992)
Classification Average Strength (N/mm2) Average Strength (kg/cm2)
35 35 350
30 30 300
25 25 250
20 20 200
17.5 17.5 175
15 15 150
12.5 12.5 125

10 | P a g e
SAQIB IMRAN 0341-7549889 10
Classification Average Strength (N/mm2) Average Strength (kg/cm2)
10 10 100
7.5 7.5 75
5 5 50
3.5 3.5 35
Compressive Strength Test of Bricks
The determination of Compressive Strength Test of Brick is carried out under the specification
of ASTM C67-03.
Sampling of Brick
 Selection of Test Specimen: Full-size representative bricks should be sampled randomly
to cover the whole range color, texture, and sizes from a shipment.
 Numbers of Test Specimen: At least 10 bricks should be chosen from each lot of
1000000 bricks or fraction thereof. For larger lots, five individual bricks should be
chosen from each lot of 500000 bricks or fraction thereof.
Each sample must be marked for identification purposes. Markings must not cover more than 5%
of the superficial area of the sample.
Weight determination
Drying
The test specimens should be dried in a ventilated oven at 230o
F to 239o
F (110o
C to 115o
C) for at
least 24 hours and until two successive weighting at intervals of 2 hours shows an increment of
loss not greater than 0.2% of the last previously determined weight of the specimen.
Cooling
After drying, the specimens need to be cooled in a drying room. The temperature must be kept
75+15o
F (24+8o
C), with a relative humidity between 30 and 70%.
Materials Used

11 | P a g e
SAQIB IMRAN 0341-7549889 11
 Cement: Quick hardening cement
 Sand: Locally available good quality sand
 Capping Material: Capping is usually done either using gypsum or Sulphur clay mixture. For the
later, a mixture containing 40 to 60 weight % Sulphur, the remainder being fire clay or other
suitable inert material passing a No.100 sieve with or without plasticizer is used.
Apparatus
 Capping Mold: Four 1 inch (25.4 mm) square steel bars on the surface plate to form a
rectangular mold approximately ½ inch (12.7 mm) greater in either inside dimension than the
brick specimen used.
 Testing Machine
Test Procedure
Preparation of the Sample
Dry half bricks with full height and width of the unit and length equal to one half of the full
length of the unit + 1 inch (25.4 mm). Ends should be plane and parallel.
Capping the Specimen
1. If the surface which will become the bearing surfaces during the compression test is
recessed or paneled, the depressions have to be filled with a mortar composed of 1 part
by weight of quick-hardening cement and 2 parts by weight of sand. The specimens are
to be aged at 48 hours before capping them. Where the recess exceeds ½ inch (12.7
mm), a brick or tile slab section or metal plate is used as a core fill.
2. The capping mold is to be placed.
3. The Sulphur mixture is to be heated in a thermostatically controlled heating pot to a
temperature sufficient to maintain fluidity for a reasonable period of time after contact
with the surface being capped. Care is required to prevent overheating and the liquid is
to be stirred before using.
4. The mold should be filled to a depth of ¼ inch with molten Sulphur material. The surface
is to be placed in the liquid vertically.
5. The unit must remain undisturbed for minimum 2 hours until solidification.
Testing the Specimen
1. Brick specimens are to be tested flatwise. The specimen is to be centered under the
spherical upper bearing within 1/16 inch.

12 | P a g e
SAQIB IMRAN 0341-7549889 12
Figure:
Compressive Strength Test of Brick
2. The load should be applied up to one half of the expected maximum load, at any
convenient rate. Then the remaining load has to be applied at a uniform rate in 1-2
minutes.
Calculation:
Compressive Strength, C= (W/A)
Where,
W= Calibrated maximum load
A= Average of the gross areas of the upper and lower bearing surfaces of the
specimen.
Uses of Bricks
Brick plays very important role in the field of civil engineering construction. Bricks are used as
an alternative of stones in construction purpose. Here some main uses of construction brick are
given below.
 Construction of walls of any size
 Construction of floors
 Construction of arches and cornices
 Construction of brick retaining wall
 Making Khoa (Broken bricks of required size) to use as an aggregate in concrete
 Manufacture of surki (powdered bricks) to be used in lime plaster and lime concrete
Properties of Bricks.

13 | P a g e
SAQIB IMRAN 0341-7549889 13
The essential properties of bricks may be conveniently discussed under the following four
headings: physical, mechanical, thermal and durability properties.
(1) Physical Properties of Bricks.
These properties of bricks include shape, size, color, and density of a brick.
(i) Shape.
The standard shape of an ideal brick is truly rectangular. It has Well defined and sharp edges.
The surface of the bricks is regular and even.
Special purpose bricks may, however, be either cut or manufactured in various other shapes.
These are generally modifications of rectangular shapes.
(ii) Size.
The size of brick used in construction varies from country to country and from place to place in
the same country. In India, the recommended standard size of an ideal brick is 19 x 9 x 9 cm
which with mortar joint gives net dimensions of 20 x 10 x 10 cm.
These dimensions have been found very convenient in handling and making quantity estimates.
Five hundred such bricks will be required for completing 1 m3 brick masonry.
It may be interesting to note that in U.K, U.S, the commonly used bricks have following
dimensions: The Standard size of Brick in India, US, UK.
Country Length (cm) Thickness (cm) Height (cm)
Standard Size of Brick in UK. 20 9.5 5.5
Standard Size of Brick in US. 20 10 10
Standard Size of Brick in India. 19 9 9
(iii) Color.
The most common color of building bricks falls under the class RED. It may vary from deep red
to light red to buff and purple. Very dark shades of red indicate over burnt bricks whereas
yellow color is often indicative of under-burning.
(iv) Density.
The density of bricks or weight per unit volume depends mostly on the type of clay used and
the method of brick molding (soft-mud, Stiff-mud, hard-pressed etc.).
In the case of standard bricks, density varies from 1600 kg/cubic meter to 1900 kg/cubic meter.
A single brick (19 x 9 x 9 cm) will weigh between 3.2 to 3.5 kg. depending upon its density.
(2) Mechanical Brick Properties.
Under this heading of properties of bricks, compressive strength and flexure strength are
included.
(i) Compressive Strength of Bricks.
It is the most important property of bricks especially when they are used in load-bearing walls.
The compressive strength of a brick depends on the composition of the clay and degree of
burning. It may vary from 35 kg/cm2 to more than 200 kg/cm2 in India.

14 | P a g e
SAQIB IMRAN 0341-7549889 14
It is specified under the I.S.S. codes that an ordinary type building brick must possess a
minimum compressive strength of 35 kg/cm2. The first and 2nd class bricks shall have a
compressive strength not less than 70 kg/cm2 and 140 kg/cm2 respectively.
(ii) Flexure Strength.
Bricks are often used in situations where bending loads are possible in a building. As such, they
should possess sufficient strength against transverse loads. It is specified that the flexural
strength of a common building brick shall not be less than 10 kg/cm2. Best grade bricks often
possess flexural strength over 20 kg/cm2. Similarly, it is required that a good building brick shall
possess a shearing strength of 50-70 kg/cm2.
(3) Thermal Properties of Building Bricks.
Besides being hard and strong, ideal bricks should also provide an adequate insulation against
heat, cold and noise. The heat and sound conductivity of bricks vary greatly with their density
and porosity. Very dense and heavy bricks conduct heat and sound at a greater rate. They have,
therefore, poor thermal and acoustic (sound) insulation qualities. For this reason, bricks should
be so designed that they are light and strong and give adequate insulation.
(4) Durability.
By durability of bricks, it is understood that the maximum time for which they remain unaltered
and strong when used in construction. Experience has shown that properly manufactured
bricks are among the most durable of man-made materials of construction. Their life can be
counted in hundreds of years. The durability of bricks depends on some factors such as:
absorption value, frost resistance, and efflorescence.
(i) Absorption Value.
This property is related to the porosity of the brick.
True Porosity is defined as the ratio of the volume of pores to the gross volume of the sample
of the substance. Apparent porosity, more often called Absorption value or simply absorption,
is the quantity of water absorbed by the (brick) sample. This is expressed in percentage terms
of the dry weight of the sample:
Absorption=W2 – W1 / W1 x 100
Where W2 is weight after 24 hours of immersion in water and W1 is the oven dry weight of the
sample. The absorption values of bricks vary greatly. It is, however, recommended that for first
class bricks, they shall not be greater than 20 percent and for ordinary building bricks, not
greater than 25 percent. The absorption characteristic of bricks effects their quality in many
ways:
Firstly: higher porosity means less solid materials; hence, strength is reduced.
Secondly: higher absorption will lead to other water-related defects such as frost-action and
efflorescence.
Thirdly: higher absorption results in deeper penetration of water which becomes a source of
dampness.
(ii) Frost Resistance.

15 | P a g e
SAQIB IMRAN 0341-7549889 15
Water on freezing expands by about 10% in volume and exerts a pressure on the order of 140
kg/cm2. When bricks are used in cold climates, their decay due to this phenomenon of “frost
action” may be a common process. This is especially so because bricks are quite porous
materials (apparent porosity = 20-25%). It is, therefore, essential that bricks in these areas
should be properly protected from rain to minimize absorption.
(iii) Efflorescence.
It is a common disfiguring and deteriorating process of bricks in hot and humid climates.
Brick surface gets covered with white or gray colored patches of salts. These salts are present in
the original brick clay. When rain water penetrates into the bricks, the salts get easily dissolved.
After the rains, evaporation starts. The salts move out along with the water and form thin
encrustations on the surface of the bricks. Salts which are commonly precipitated during
efflorescence are: sulfates of calcium, magnesium, sodium and potassium. It is why great
emphasis should be laid while testing the chemical composition of the clay for brick
manufacturing.
SUMMARY (Properties of Bricks).
1. It should have a rectangular shape, regular surface and red colored appearance.
2. It should confirm in size to the specified dimensions (19 x 9 x 9 cm).
3. It should be properly burnt. This can be ascertained by holding two bricks freely, one in each
hand, and striking them. A sharp metallic sound indicates good burning whereas a dull thud
would indicate incomplete burning.
4. A good building brick should not absorb water more than 20 percent of its dry weight.
Absorption should not exceed 25 percent in any case.
5. A good building brick should possess requisite compressive strength, which in no case should
be less than 35 kg/cm2. A rough test for the strength of the brick is to let it fall freely from a
height of about one meter on to a hard floor. It should not break.
6. Brick should be hard enough so that it is not scratched by a finger nail.

16 | P a g e
SAQIB IMRAN 0341-7549889 16
7. A good brick has a uniform color and structure through its body. This can be checked by
taking a brick from the lot and breaking it into two parts. The broken surface in both the halves
should have same appearance and structure.
Special Types of Bricks:
Ordinary building bricks are typically rectangular in shape, solid in structure and made from a
Suitable type of brick-clays.
In building construction, however, bricks of modified Shapes, porous or hollow structure and
also made from materials other than clay are also sometimes used.
A familiarity with this Special classification of bricks is quite important for a construction
engineer and an architect. We Shall discuss them below.
Classification of Bricks Based on Modification in Shape.
In construction, there are positions where a perfect rectangular shape brick will not be suitable.
It has to be modified.
Such bricks are required in the plinth, the corners of the walls and at the copings.
There is a long list of such Special-Shaped bricks… We will discuss the important ones here.
i. Squint Brick:
They are cut on one corner at an angle of other than 90 degrees. They are required for giving
shape to an exterior or interior corner in a wall.
ii. Splay or Can Brick:
These have a level or portion taken off, width wise, length wise, or in both directions. The
various shapes grouped under splay bricks are made for use in jambs of doors and windows and
also in plinths.
iii. Coping Bricks:
They are used for coping on walls in order to give them a nice appearance and also for easy
drainage of water.
When a coping is to be provided to a wall, a special shape may be desired. The chamfered, the
half round, and the saddleback bricks are some common coping bricks.
iv. Bullnose:
Bullnose bricks are used at turns of the wall so that round corners are obtained. It is a standard
brick having one edge rounded.

17 | P a g e
SAQIB IMRAN 0341-7549889 17
v. Cownose:
It is similar to bullnose, but it has both edges rounded on one side. It may also be called double
bullnose bricks. They have the same use as bullnose, but they just give additional roundness.
Classification of Bricks based on Cavities:
Three types of bricks shall be discussed under this category.
i. Perforated Bricks:
These form a modem class of building bricks that have many advantages over the ordinary solid
brick. In perforated bricks, cylindrical, rounded or rectangular holes are made in the bricks after
the molding stage. These holes are called perforations.
They are properly spaced from the side of the brick, and the minimum distance is 15 mm.
Further, a distance between any two perforations is not less than 10 mm.
The volume of the perforations may be as much as 20 – 50 percent of the total volume of the
brick. They may be larger in size than ordinary building brick which is a distinct advantage in
that work output of a Mason will increase considerably with the use of perforated bricks.

18 | P a g e
SAQIB IMRAN 0341-7549889 18
The
major advantages that perforated bricks offer over ordinary bricks are:
(i) They are light in weight.
(ii) Less quantity of clay is required for their manufacture.
(iii) Less time is required for drying and burning of perforated bricks.
(iv) These offer better resistance against rain penetration and better insulation against heat. As
such they are ideally suited for tropical countries.
(v) Efflorescence is least in perforated bricks.
(vi) These are especially suitable for the construction of brick panels in multi-story structures.
Perforated bricks have as yet to find popularity in all countries although they are already widely
used in Germany, France, and America.
Already there is a trend for their use.
The manufacture of perforated bricks requires slightly sophisticated technology, and that is the
main reason for lesser use in all over the world.
ii. Hollow Bricks:
Hollow bricks also called cavity bricks or cellular bricks they have well-defined sets of cavities
with specified dimensions made in the body of the brick.
As a result, their net weight may be only one-third to one-half of the solid portion. It is
important that the thickness of the brick wall near the cavity should not be less than 2 cm.
The hollow bricks are made from a special type of brick clay (which should have higher clay
content).
They offer the following advantages over the ordinary types of bricks.
(i) Being light in weight, they can be handled more conveniently, and the output of the mason
may be three to four times compared to ordinary bricks.
(ii) They offer better insulation against heat and sound.
(iii) They are ideal and economical for non-load-bearing walls, e.g., in partition walls.

19 | P a g e
SAQIB IMRAN 0341-7549889 19
iii. Channel OR Gutter Bricks:
They are actually special purpose bricks baring a continuous central semi-circular cavity or
depression running through their length.
Very often they are glazed to make them impervious: They are mostly used in the laying of
drains.
Classification of Bricks Based on Composition:
We will discuss 2 major classification of bricks here below.
i. Sand LIME Bricks:
Definition. These are building bricks made from sand and lime as the raw materials instead of
clay. The clay content may be only negligible.
They differ from ordinary clay bricks not only in composition but also in the method of
manufacture. They are, however, similar in shape and size to the ordinary types of bricks.
Manufacture. The principal raw materials for sand-lime bricks are:
(1) Sand. It must be free from harmful impurities like chloride, iron oxides, black minerals and
organic matter. Sand forms around 90 percent of sand-lime bricks.

20 | P a g e
SAQIB IMRAN 0341-7549889 20
(ii) Lime. It is used in the form of a slaked (hydrated) lime. Its content varies from 8-12 percent.
The slaked lime used for brick making has high calcium-content and should be free from
magnesium.
Besides the two essential components, some clay (up to four percent) in finely divided form is
desirable. Pure, salt-free water (not sea water) is another requirement.
For giving a required color to the sand-lime bricks, some pigments are added in small
percentages to the ingredients at the mixing stage.
Among these pigments, the following are used Commonly;
Iron-oxides for red and brown color.
Chromium Oxide for green color.
Ochre for yellow color.
Carbon black for Grey and black color.
Molding. After mixing the finely powdered raw materials in the desired proportion, a damp
mixture is obtained adding 2-3 per cent clean water.
From this damp mixture, brick-shaped units are molded using ROTARY PRESS. Pressures applied
range from 300-600 kg/cm2.
Such high-pressure results in highly compressed and dense sand-lime bricks which are almost
dry at this stage.
Autoclaving. The molded units are put into an autoclave (a steel cylinder with the closed end
where heating is done by steam under pressure).
In the autoclave, the bricks are treated for 6-12 hours under steam pressures between 8-16
kg/cm2. It is in the autoclave that sand and lime react chemically and form a chemical
compound, calcium-silicate. That is the chemical composition of the sand-lime brick.
The sand-lime bricks taken out from the autoclave are ready for use.
Properties of Sand Lime Bricks.
(i) The sand-lime bricks have a very smooth and uniform finish and a pleasing appearance.
(ii) They are quite dense, strong and hard.
(iii) They are least porous and hence free from efflorescence.
Because of these properties, sand-lime bricks offer many advantages.
(i) They are uniform in shape, size and finish and hence require no plastering.

21 | P a g e
SAQIB IMRAN 0341-7549889 21
(ii) The quantity of plaster when required is quite less because of the smooth surface of the
brick.
(iii) They are water repelling and hence free from absorption related defects of ordinary bricks.
(iv) Since the materials required for sand-lime bricks are also quite common in occurrence,
these can provide a suitable alternative to clay-bricks.
We should know that most clay used in making bricks is from agricultural lands and hence its
conservation will help in increasing food production.
Among the major disadvantages of sand-lime bricks, the following may be mentioned:
(i) They can be manufactured only by using mechanized methods. Hence their production at
village levels is almost impossible at present.
(ii) They are unsuitable for foundations and paving uses. In the first case, they get damaged in
the presence of water, and in the second case, it is because they have poor resistance to
abrasion.
The Scope of Use. In Western countries, sand-lime bricks are used quite widely. Sooner or later,
they will have to be introduced in other countries too on a large scale.
ii. Fire OR Refractory BRICKS:
Definition. This is a separate group of bricks which is capable of withstanding in very high
temperatures without undergoing any deformation in shape or size and without reacting with
the material of a particular composition.
Their use is restricted to the making of inner walls of furnaces for the manufacture
of metals and for similar high-temperature applications.
Classification:
The firebricks are classified on the basis of their reactivity towards melts at high temperatures:
(a) Acidic Bricks. They are resistant to the melts of acidic composition (but will react with the
melts of basic composition).
Example: Fire-clay bricks, silica bricks.

22 | P a g e
SAQIB IMRAN 0341-7549889 22
(b) Basic Bricks. They are resistant to the melts of basic composition. Hence they will not be
suitable for use in those furnaces where acidic melts are being heated.
Examples: Magnesia bricks, Bauxite bricks.
(c) Neutral Bricks. They are non-reactive to both the acidic and basic melts. Hence these find
applications in heating either type of melts.
Examples: Chromite bricks, Chrome-magnesite bricks.
Manufacture of Fire Bricks.
They are manufactured in the same manner as a building Brick. The four stages are involved in
their manufacture process are:
 Moulding
 Drying
 Burning
 Cooling
The Raw Materials are first crushed in to the required size and then blended are mixed
thoroughly in the presence of required quantity of water.
After this process Brick are molded manually or by using Machines such as “Presser “.
The molded Bricks are dried and then burnt in a very high temperature, generally between
1600 to 2000 Centigrade.
After this Process they are allowed to cool very gradually.
Description of important Fire Bricks or Refractory Bricks.
(a.) Fire Clay Bricks.
These constitute are an important class of refractory materials of acidic group. Raw material for
its manufacturing can withstand at very high temperatures without fusing or softening.
Such clay is often available under the coal layers in nature.
Silica (65-75 Percent) and alumina (25-35 Percent) are the two main constituents of Fire Clay.
They are free from impurities like oxides of calcium, magnesiumand iron. The maximum
permissible upper limit for all such impurities is 5 Percent.
These are manufactured in a manner similar to the common building Brick. The selected clay is
crushed to the fine powder and molded into the brick unit.
These are than dried and burnt in Continuous kiln at very high temperature (1600 to 1900
centigrade). They are cooled gradually before taking out from the kiln.
Types.
They are divided into three types on the basis of temperature.
High Duty. (1482 to 1648 Centigrade).
Medium Duty (1315 to 1481 Centigrade)
Low Duty (870 to 1314 Centigrade)
Properties.
They have high resistance to palling, high bearing capacity and low coefficient of thermal
expansion.
Uses.

23 | P a g e
SAQIB IMRAN 0341-7549889 23
They are commonly used as a lining material in steel making furnaces and reverberatory
furnaces.
(b.) Silica Fire Bricks.
These are made up mostly of silica, which may range from 95 percent or above. The remaining
material is generally calcium oxide that act as binding agent. These are acidic in character. Their
raw materials are pure quartz (SiO2), or sandstone of high silica content. The molded unit are
burnt in about 1500 Centigrade. They are extensively used in Bessemer Converter as lining
material because slag in that case are acidic in nature.
(c.) Magnesite Fire Bricks.
They are classed among the basic refractories. There raw material is magnesium oxide. The
major source for it is Dolomite rock.
(d.) Bauxite Fire Brick.
They also form a very important class of Basic Refractories. They are made from the
rock Bauxite (Al2O32H2) which are mixed with some clay (Fire Clay type).
(e.) Chromite Fire Bricks.
They are belonging to the neutral class of refractories. Raw material used for these Fire Bricks is
a mineral called CHROMITE.
The mineral is double oxide of chromium and iron in its composition. These types Refractory
bricks are capable of resisting both the acidic and basic environments in a furnace.
These type of fire brick are commonly used in the steel making furnaces.
Functions of various constituents of brick-earth
Composition.

24 | P a g e
SAQIB IMRAN 0341-7549889 24
A good brick-earth should be such that when prepared with water it can be easily moulded,
dried and burnt with out cracking or warping. It should contain a small quantity of finely divided
lime to help in binding the particles of brick together by melting the particles of sand. A little
oxide of iron should also be present which would give the brick its peculiar red colour and act in
the same manner as lime.
A good brick earth should preferably conform to the following composition:
Clay (Alumina) 20 to 30 per cent by weight
Silt 20 to 35 per cent by weight
Sand 35 to 50 per cent by weight
The total content of clay and silt should not as far as possible be less than 50% by weight.
functions of brick constituent
(i) Silica or Sand.
It is present either free as sand or in combination as silicate of alumina. Silica is in fusible except
at very high temperatures but in the presence of alumina in nearly equal proportions and the
oxide of iron to fuses at lower temperatures. Unlike silicate of alumina its presence in clay
produces hardness, resistance to heat, durability and prevents shrinkage and warping. Excess of
it makes the brick brittle.
(ii) Alumina.
It is a tenacious finely-grained mineral compound present in brick-earth. It is plastic, when wet,
and in capable of being molded to any shape. On drying it loses its plasticity and becomes hard,
shrinks, warps and cracks. Burning causes the fusion of its constituents thereby making it
homogeneous, harder and stronger.
(iii) Lime.
When present in small quantities in finely divided state it reduces shrinkage of bricks and acts
as a flux causing silica to melt. It results in binding the particles of brick together resulting in
greater strength of brick. Excess of lime causes the brick to melt and lose its shape.
(iv) Magnesia.
In the presence of iron, it gives a yellowish tint to the bricks. It should not be present in excess.
However, the presence of small quantity of manganese with iron will give the brick darker or
even black colour. Total lime and magnesia in case of alluvial soil shall not be more than one
per cent and in other cases it will preferably not exceed 15 per cent.
(v) Oxide of iron.
In the presence of silica and alumina, it helps the fusion of brick particle. Also it influences the
colour of bricks. It produces a tint varying from light yellow to red depending upon the
percentage of iron present in clay. Excess of it makes the colour dark blue. It should not be
present in the form of iron pyrites.
Harmful ingredients.
(i) Lime.
If present in excess, it melts the brick particles as a result of which the brick loses shape. Lime
should also be not present in brick-earth in the form of lime stone or kankar modules. On the

25 | P a g e
SAQIB IMRAN 0341-7549889 25
burning of bricks, these get converted to quickline which expands on absorption of moisture
and causes the cracking and disintegration of bricks.
(ii) Iron pyrites.
Iron pyrites get oxidized in the brick, crystallize and split the brick to pieces. These should be
carefully removed from brick-earth.
(iii) Pebbles of stone and gravel etc.
Their presence makes it difficult to mix the brick-earth thoroughly as a result of which the bricks
are not homogeneous. It gives weak and porous bricks. Also such bricks cannot be readily cut or
worked.
(iv) Alkalies.
Their excessive presence in earth renders it unsuitable for bricks. These act as flux causing the
bricks to melt, twist and warp. Presence of common salt in earth taken from seashores or from
near salt formations has similar effects to those narrated above and also make the
bricks hygroscopic thereby causing efflorescence.
(v) Reh or Kallar.
It is the sulphate of soda mixed with a little carbonate of soda and common salt. Its presence in
brick earth prevents bricks from being properly burnt. After the bricks have been burnt these
salts recrystallize and appear as irregular and unsightly white patches on the surface of bricks.
They cause the plaster and the surface of bricks to peel-off layer by layer and to ultimately
crumble away. Presence of reh or kallar in soil could be easily detected by the presence of
efflorescence on the sides of fresh excavation, if the soil is moist.
Bricks are rectangular units of construction material. Bricks are used in masonry construction,
walls, and pavements. It is used as a substitute of stone, where the stone is not readily
available. Brick chips are often used as coarse aggregate in the concrete mix.

26 | P a g e
SAQIB IMRAN 0341-7549889 26
Figure: Raw (Green) Bricks
Percentage of Constituents of Brick (Weight Basis)
There are six major ingredients of brick. The general percentage of these ingredients in brick is
given below:
Ingredient Percentage in
brick
Silica (SiO2) 55%
Alumina (Al2O3) 30%
Iron Oxide (Fe2O3) 8%
Magnesia (MgO) 5%
Lime(CaO) 1%
Organic Matter 1%
Chief Ingredients of Brick and Their Functions
Silica (Sand) and Alumina (Clay), these two are the most prominent ingredients in brick clay.
When mixed with water in proper proportions, it gains plasticity. The plastic mass can be easily
molded and dried. It should not go through cracking, shrinkage or warping.
Alumina
Alumina is the main constituent of clay. It acts as a cementing material in raw brick. Brick clay is
plastic due to the presence of alumina. This plasticity ensures that bricks can be molded. An
excess amount of alumina in clay may cause the bricks to shrink, warp or crack on drying and
burning as any other cementing material.
Figure: Clay for Brick formation
Silica
Good quality bricks contain 50-60% silica. It is present in both free and combined form. As frees
sand, it remains mechanically mixed with clay. In combined form, it reacts with alumina to form
aluminosilicates. Silica prevents raw bricks from cracking, shrinking and warping. The higher the
proportion of sand, the more and shapely and uniform in texture will be the brick. Although,

27 | P a g e
SAQIB IMRAN 0341-7549889 27
excess silica destroys cohesion between the brick clay particles and makes brick brittle and
weak. The durability of bricks largely depends upon the proper proportion of silica and alumina.
Figure: Sand
Lime
Bricks should contain a little amount of finely powdered lime. It enables silica (of a required
portion) to melt at the furnace temperature of 1650oC and binds the particles of brick together
resulting in strong and durable bricks. At about 1100o C, lime acts as a catalyst to elevate the
furnace temperature to 1650oC at which silica fuses. This slightly fused silica works as a strong
cementing material. Excess lime in brick clay will cause vitrification of bricks. It causes bricks to
melt, as more than the required amount of silica will fuse. The bricks then lose their shape and
become disfigured.
Figure: Powdered Lime
Iron Oxide
Bricks contain a small quantity of Iron Oxide. Iron Oxide acts a flux like lime, thus helps silica to
fuse at low temperature. It imparts a red color to bricks upon burning. Iron also increases the
durability and impermeability of the bricks.

28 | P a g e
SAQIB IMRAN 0341-7549889 28
Figure: Iron Oxide powder
Magnesia
A small proportion of magnesium decreases shrinkage and gives a yellow tint to the bricks. An
excess amount of it causes bricks to decay.
Harmful Ingredients of Brick
Lime
Excess lime melts the bricks and disfigures it. If CaCO3 exists (in the purest form, i.e., if it
contains at least 95% CaO) in lime-lump in brick clay, it converts into quicklime on burning.
When these bricks come in contact with water, quicklime slakes and expands. And causes
disintegration of bricks.
Alkalis
Alkalis are mainly salt of Sodium (Na) and Potassium (K). It acts as a flux in the kiln and causes
fusion, warping, and twisting of bricks. Alkalis absorb moisture from the atmosphere and cause
dampness & efflorescence in bricks (because of the presence of hygroscopic salts, e.g., CaCl2,
MgCl2, etc.).
Pebbles, Stones & Gravels
Their presence does not allow thorough mixing of earth, thus the bricks produced are weaker.
Such bricks cannot be broken at the desired section and they break very irregularly.

29 | P a g e
SAQIB IMRAN 0341-7549889 29
Figure: Pebbles, Stones, and Gravels
Iron Pyrites (FeS)
Iron Pyrites causes crystallization & disintegration of bricks while burning. It discolors bricks in
the form of black slag.
Organic Matter
Organic matter in bricks makes bricks porous resulting in low density and weaker bricks.
Nomenclature of cut-bricks
Brick NomenclatureFrequently, the Builder must cut the brickinto various shapes. The most
common shapes are shown in figure 7-50. They are called half or bat,three-quarter closure,
quarter closure, kingclosure, queen closure, and split. They are usedto fill in the spaces at
corners and such other places where a full brick will not fit. The six surfaces of a brick are called
the cull, the beds, the side, the end, and the face, as shownin figure 7-51. Brick ClassificationA
finished brick structure contains FACEbrick (brick placed on the exposed face of the
structure) and BACKUP brick (brick placed behind the face brick). The face brick is often of
higher quality than the backup brick; however, the entire wall may be built of COMMON brick.

30 | P a g e
SAQIB IMRAN 0341-7549889 30
Common brick is brick that is made from pit-run clay, with no attempt at color control and no
special surface treatment like glazing or enameling. Most common brick is red. Although any
surface brick is a face brick as distinguished from a backup brick, the term face brick is also used
to distinguish high-quality brick from brick that is of common-brick quality or less. Applying this
criterion, face brick is more uniform in color than common brick, and it may be obtained in a
variety of colors as well. It maybe specifically finished on the surface, and in any case, it has a
better surface appearance than common brick. It may also be more durable, as a result of the
use of select clay and other materials, or as a result of special manufacturing methods. Backup
brick may consist of brick that is inferior in quality even to common brick. Brick that has been
underburned or overturned, or brick made with inferior clay or by inferior methods, is often
used for backup brick. Still another type of classification divides brick into grades according to
the probable climatic conditions to which it is to be exposed. These are as follows: GRADE SW is
brick designed to withstand exposure to below-freezing temperatures in amorist climate
like that of the northern regions of the United States. GRADE MW is brick designed to withstand
exposure to below-freezing temperatures in a drier climate than that mentioned in the
previousparagraph. GRADE NW is brick primarily intended for interior or backup brick. It may
be used exposed, however, in a region where no frost action occurs, or in a region where frost
action occurs, but the annual rainfall is less than 15 in.
DIFFERENT CUTS AND ORIENTATIONS OF BRICKS USED IN CONSTRUCTION
1. BRICK ORIENTATION:
(i). HEADER:

31 | P a g e
SAQIB IMRAN 0341-7549889 31
The shorter side or end face of a brick that is exposed is termed as header.
(ii). STRETCHER:
The longer narrow side or face of a brick that is exposed is termed as stretcher.
(iii). ROWLOCK:
The head is visible and the long narrow sides are on bottom and top.
(iv). ROWLOCK STRETCHER:

32 | P a g e
SAQIB IMRAN 0341-7549889 32
When the thinner stretcher sides are on bottom and top faces on the sides.
(v). SAILOR:
The heads are on top and bottom and the stretcher faces are on the side. Mostly used for
decoration.
(vi). SOLDIER:
The stretcher side is visible and the heads are at the bottom and top. It is usually used for
decoration.

33 | P a g e
SAQIB IMRAN 0341-7549889 33
2. DIFFERENT TYPES OF BRICK CUTS
1. CLOSER:
Closer is the small piece of brick cut lengthwise in such a manner that its one long face remains
uncut and used at the end of masonry wall to maintain bond pattern.
(i). QUEEN CLOSER (HALF):
When a brick is cut along its length, making it two equal pieces then it is called queen closer.
(ii). QUEEN CLOSER (QUARTER):
When a queen closer is cut in to two equal pieces then it is called as queen closer quarter.
(iii). KING CLOSER:

34 | P a g e
SAQIB IMRAN 0341-7549889 34
King closer are the portion of a brick obtained by cutting off the triangular piece between
center of one end and the center of one side.
(iv). BEVELLED CLOSER:
Similar to king closer with the only difference that the whole length of the brick bevelled for
maintaining the half width at one end and full width at the other.
(v). MITRED CLOSER:
It is a brick whose one end is cut splayed or mitred for full width. The angle of splay vary from
45 to 60 degree.
2. BAT:
The portion of bricks cut across the width is termed as bat.

35 | P a g e
SAQIB IMRAN 0341-7549889 35
(i). THREE QUARTER BAT:
It is the form of brick bat having its length equal to three quarter of length of a full brick.
(ii). HALF BAT:
If the length of the bat is equal to half the length of the full bricks.
(iii). BEVELED BAT:
A brick bat is called beveled bat when its width has beveled.
COLOURS OF BRICKS
The colours of bricks as obtained in its natural course of manufacture depend on the following
factors

36 | P a g e
SAQIB IMRAN 0341-7549889 36
 Degree of dryness achieved before burning
 Natural colour of clay and its chemical composition
 Nature of sand used in moulding operation
 Quality of fuel used in burning operation
 Quantity of air admitted to the kiln during burning
 Temperature at which bricks are brunt
COLOURS OF BRICKS
No. Colour Constituents Present in Clay
1 Black Manganese and large proportion of iron
2 Bluish Green Alkalies
3 Bright red, dark blue or purple Large amount of iron oxide
4 Brown Lime in excess
5 Cream Iron and little lime
6 Red Iron in excess
7 White Pure clay
8 Yellow Iron and magnesia
The artificial colouring of bricks is achieved by adopting one of the following two methods
1. Addition of colouring material
2. Dipping in colouring liquid
1. Addition of Colouring Material:

37 | P a g e
SAQIB IMRAN 0341-7549889 37
In this method the required colouring material is added in brick earth. The bricks prepared from
such earth will present the desired colour. The usual colouring materials are iron oxides,
manganese, French ultramarine, Indian red etc. This method is adopted when the colouring
material is cheap and when it is available in plenty.
2. Dipping in Colouring Liquid:
In this method an earthenware box which is slightly larger each way than a common bricks is
taken. It is filled nearly to 1/2 depth with liquid which is in the form of thick paste. The bricks to
be coloured are placed on an iron plate and with a fire underneath they are heated to such an
extent that they can be easily handled. One brick is taken at a time and it is allowed to stay for
few seconds in the box. It is then placed aside to dry.
The colouring liquid is formed by the addition of colouring material to a mixture of lineseed oil,
litharge and turpentine. The proportion of various component of colouring liquid for different
colours.
COLOURING LIQUID
Component
Name of the Colour
Black Blue Dark red Grey
Lineseed oil 1.20 N 570 c.c. 850 c.c. 0.60 N
Lintharge 0.60 N 0.15 N 1.15 N 0.30 N
Turpentine 1.80 N 570 c.c. 850 c.c. 1.20 N
Manganese 1.80 N - - 0.30 N
French ultramarine - 4.50 N - -
Indian red - - 0.15 N -
White lead - - - 0.90 N
Following are the advantage of this method-
1. The bricks which are coloured by this method do not lose their colours, when exposed
to the atmosphere.
2. It can be adopted for expensive colours
3. It is possible to develop a variety of colours cheaply and easily
4. The penetration of colouring liquid in ordinary bricks ia adbout 3 mm or so.

38 | P a g e
SAQIB IMRAN 0341-7549889 38
5. This method can be used for brick wall which are already constructed. The wall surface
is carefully cleaned. The colouring liquid is slightly heated and it is applied on the wall
surface with a brush.
SIZE, WEIGHT AND FACTORS AFFECTING QUALITY OF BRICKS
SIZE AND WEIGHT OF BRICKS
The bricks are prepared in various sizes. The custom in the locality is the governing factor for
deciding the size of a brick. Such bricks are not standardized are known as the traditional bricks.
It bricks are large it is difficult to burn them properly and they become too heavy to be placed
with a single hand. On the other hand, if bricks are small more quantity of mortar is required.
For India a brick of standard size 190 mm x 90 mm x 90 mm is recommended by BIS. With
mortar thickness the size of such a brick becomes 20 mm x 10 mm x 10 mm and it is known as
the nominal size of the modular bricks. Thus the nominal size of brick includes the mortar
thickness.
It is found that the weight of 1 m3 of brick earth is about 18 KN. Hence the average weight of a
brick will be about 30 to 35 N.
FACTORS AFFECTING QUALITY OF BRICKS
Following factors affect the quality of bricks-
 Composition of brick earth
 Preparation of clay and blending of ingredient
 Nature of moulding adopted
 Care taken in drying and stacking of raw or green bricks
 Types of kiln used to include type of fuel and its feeding
 Burning and cooling processes
 Care taken in including
It is thus obvious that not only the bricks of different brick fields will have different strength,
but in the same brick field, the bricks of the same batch may have different strengths.
The average crushing strength and tensile strength of hand moulded bricks are 60000 KN/m2
and 2000 KN/m2 respectively. In practice however the bricks are not subjected to the tensile

39 | P a g e
SAQIB IMRAN 0341-7549889 39
stresses. It may be noted that the strength of brickwork mainly depends on the types of mortar
used and not so much on the individual strength of the bricks.
How to check quality of Bricks on site?
Bricks are building blocks of a structure. Brick is most extensively used materials of the building
construction.
As an Engineer, you must know how to check the quality of bricks on site. A good quality of
brick should be chemically inert that means it won’t show any reaction when it mixed with any
material.
In this post, I am making you learn how to check the quality of bricks on site and what are the
qualities of a good brick.
To chose the right quality of brick one should test the brick for following tests: -
1. Uniform Color, Size, and Shape:
Colour & shape of Brick: -
A good quality of bricks should be well burnt and have a colour of rich red or Copper colour, any
other colour other than above resembles that brick is under burnt or over-burnt. If bricks are
over or under-burnt, then it loses it shape.
Size of Brick: -
Brick should be uniform in size it shouldn’t have any bulks on edges.
More the bulking in brick needs more mortar. It ultimately increases the cost of a building. A
good brick should be sharp at edges.
A good quality of bricks should have an accurate dimension whereas +/- 3 tolerance is allowed.
2. Hardness of brick: -

40 | P a g e
SAQIB IMRAN 0341-7549889 40
Best quality of brick should resist the scratches against sharp things. Scratch the brick using
your fingernail or sharp tool. A good brick should not show any impression or scratch of a
fingernail on the brick.
3. Homogeneity: -
Break the brick and examine it. A good quality brick should be homogeneous, compact and with
zero lumps.
4. Water absorption: -
A good brick should absorb less than 20% of water when it is immersed in water for 24hrs. If
the brick absorbs more than the allowable limit. It absorbs water from cement mortar during its
bonding. This eventually affects the brick bonding strength.
Water absorption test on brick: -
To test the water absorption follow the below procedure:
Take a brick and weight it as (W1)
Now immerse the brick in water for 24 hrs. and then weight it as (W2)
Find out the percentage increase of brick weight by adopting below formula
Water absorption in the brick formula:
5.Check for efflorescence on bricks: -
Efflorescence is a salt deposit seen on the surface of bricks. Usually, it’s in white. This can be
visually inspected by checking white patches on the bricks surface, White patches on bricks
resemble presence of sodium and potassium salts on it which is not suitable for construction.

41 | P a g e
SAQIB IMRAN 0341-7549889 41
Soils used in the manufacturing of bricks should free from sulphate, potassium and sodium. If
brick contains such harmful salts, then will get dissolved when bricks come into contact with
water. When bricks contain such harmful salts as used exposed surface then serious surface
disruption occur which may harm outer plastering. This phenomenon is called efflorescence.
As per IS 3495 – 1992. To check the presence of efflorescence following procedure is adopted
1. Take a flat tray and fill it with a 2.5cm height of distilled water.
2. Treat five bricks as a test specimen and place these bricks vertically one after other. On
a tray containing distilled water. Now wait until the water is absorbed by bricks
3. Again fill the water up to same height 2.5cm and allow it to absorb water as above
(Second evaporation)
4. Now after second evaporation, examine the brick for efflorescence as below:
Description Extent of Deposits

42 | P a g e
SAQIB IMRAN 0341-7549889 42
Description Extent of Deposits
Nil No perceptible deposit of efflorescence
Straight 10% area covered with a thin salts deposits.
Moderate Upto 50% area covered by heavy deposit.
No powdering or flaking
Heavy 50% or more area covered.
No powdering or flaking.
Serious Heavy Deposit
Powdering or flaking is observed
Brick is only used if the extent of efflorescence is from slight to moderate. The above-
mentioned tests are the simple and reliable test which gives an idea about the quality of bricks
on site.
6. Brick Earth:
The composition of Brick should be free from stones, kankare and other chemicals.
7. Soundness of Brick:
Take two bricks one in each hand and stuck it each other a good brick hears a metallic sound or
ringing sound. If brick breaks without sound, then it isn’t suitable for construction.
Throw the brick at the height of 1.5m to the ground. A good quality brick won’t break when it is
fallen from the 1.5m height.
8. Examine frog in brick:
Check the size of the frog and it should be 100mm x 40mm x 10mm. Any other lesser size of
frog leads to improper motor filling and requires more amount of mortar if the frog dimensions
are more than above which makes structure uneconomical.

43 | P a g e
SAQIB IMRAN 0341-7549889 43
Due to scarcity of natural resources to manufacure bricks a new types of bricks are introduced
“AAC Bricks”
Defects in bricks
There can be many defects in bricks. Identifying defective bricks is important for the
consideration of stability and durability of load bearing brick masonry walls and structures.
Types of Defects in Bricks and their Identification
Following are the different types of defects generally found in bricks:
1. Over burning of bricks
When bricks over-burn, soft molten mass is produced and the brick will its shape along with
other designated requirements.

44 | P a g e
SAQIB IMRAN 0341-7549889 44
Fig.1: over burnt bricks
2. Under burning of bricks
When bricks are not burnt to cause complete vitrification, the clay is not softened because of
insufficient heat and the pores are not closed.
Consequently, bricks with low compressive strength and high-water absorption will be
produced. They produce a dull sound when struck against each other.
Finally, such bricks are not recommended for construction works

45 | P a g e
SAQIB IMRAN 0341-7549889 45
Fig.2: under burnt bricks
3. Bloating of bricks
Bloating of bricks is spongy swollen mass over the surface of burned bricks. Presence of excess
carbonaceous matter and Sulphur in brick-clay is the main cause of bloating.
Fig.3: bloating of bricks
4. Black core
Improper burning is the prime cause of brick black core. Bricks, which contains bituminous
matter or carbon and they are not completely removed by oxidation, will commonly experience
such problem.

46 | P a g e
SAQIB IMRAN 0341-7549889 46
Fig.4: black core brick
5. Efflorescence
Presence of drying grey or white powder patches on the brick surface is the efflorescence
indicator. This defect is caused because of alkalis present in bricks. When bricks come in contact
with moisture, water is absorbed and the alkalis crystalize.
Lastly, efflorescence can be minimized by selecting proper clay materials for brick
manufacturing, preventing moisture to come in contact with the masonry, by providing
waterproof coping and by using water repellent materials in mortar and by providing damp
proof course.
Fig.5: efflorescence on bricks
6. Brick cracking
Straight cracks
Straight cracks at right angles from one of the long surfaces of the brick will develop.
Considerably rapid drying is the cause of straight cracks. Possibly, brick damage occurs even if
fired adequately.

47 | P a g e
SAQIB IMRAN 0341-7549889 47
Fig.6: brick straight cracking on one of long surfaces
Random cracks
Cracks initiate arbitrarily on different brick surfaces.
Differential drying generate shrinkage. then, various lumps of dried materials will shrinkage
differently which eventually lead to random cracking.
additionally, the presence of pebbles in clay mix could lead to random cracking as well.
Fig.7: multiple brick surface cracking in random directions
7. Brick spalling
Irregular portion of the brick break away of fall off.
Heating of water inside brick is the cause of spalling

48 | P a g e
SAQIB IMRAN 0341-7549889 48
Fig.8: Spalling of bricks
8. Chuffs
The deformation of the shape of bricks due to rain water falling on hot bricks is known as
chuffs.
9.Lime blowing
Disintegration of bricks is the indicator of lime blowing.
If bricks contain lime lump, then lime blowing is expected. The lime absorb water and expand
after its exposure to firing. Consequently, lime blowing will take place.
Bricks susceptible to lime blowing can be identified by submerging the brick in water. As a
result, the brick fractures and powdery lumps will be exposed.
Fig.9: Lime blowing defects
10. Spots
It is a dark spot on brick surface.
The presence of iron sulphide in clay brick is the main cause of spots.
Bricks with sports on its surface is unsuitable for exposed masonry work.

49 | P a g e
SAQIB IMRAN 0341-7549889 49
Fig.10: spots in bricks
11. Lamination bricks
Thin lamina produces on the brick faces which weather out on exposure.
Entrapped air in the voids of clay is the cause of laminations.
Such bricks are weak in structure.

50 | P a g e
SAQIB IMRAN 0341-7549889 50
Fig.11: Brick lamination
12. Defects in brick size
Oversize bricks
Brick oversize in width, length, and thickness
Fig.12: oversize brick in all dimensions
Size defects make bricks lighter than normal bricks
Oversize in all three dimensions of bricks might cause by under-firing, poor material selection
and preparation. For example, presence of too much sand that decline among of drying.
Oversize in width and length occur due to brick squashing while it is still wet. This may have
been occurred when the brick was set down on the ground or drying rack after being molded or
when a slop molded brick was pressed to flatten out a distortion.

51 | P a g e
SAQIB IMRAN 0341-7549889 51
Fig.13: brick set on the ground cause oversize in length and width
Oversize in thickness, which is common problem in wire cut bricks, occurs during brick wire
cutting. the block of clay is forced through a row of wires. As a result, the force on the wire may
cause movement that changes the dimension of the opening which the clay passes through.
Fig.14: over sized bricks during wire cut process
Under-size bricks
This problem occurs due to several factors for example, faulty mould, presence of too much
clay in the batch, using too much water during the mixing stage, and over firing.
13. Defects in brick shape
Slump brick shape
It occurs when clay mix is considerably wet, so it slumps under its weight.

52 | P a g e
SAQIB IMRAN 0341-7549889 52
Fig.15: Defects in brick shape; slump
Rounded corner brick
Corner breakage between drying and firing may cause this problem.
Another factor is that; the worker does not push clay into the mould properly.
Fig.16: defects in brick shape; round corner
Lip on bed face
Excessive clay is not removed from the face of the brick during manufacturing is the cause of
presence of lip on brick bed face.
Leaving flashing around brick top edge border during production process is another factor that
led to this issue.
Fig.17: Defects in brick shape, lip on top face
Banana brick shape

53 | P a g e
SAQIB IMRAN 0341-7549889 53
It occurs when the brick is not turned around during initial drying phase prior to the hardening
of top face.
Fig.18: Defects in brick shape, banana shapes
Contaminated or distorted of brick under face
Surface on which bricks are dried is either uneven or dirty of combination thereof.
Frequently, it occurs with slope moulding as wetter mixture picks up more particles.
Fig.19: defects in brick shape, contaminated or distorted brick under face
Stacking marks on bricks
Bricks distort
Bricks get finger marks or other marks
Moving bricks from individual drying to stack drying before it is dried adequately is the cause of
stacking marks.

54 | P a g e
SAQIB IMRAN 0341-7549889 54
Fig.20: defects in brick shape, stacking marks
Brick multiple distortions
It loses its shape and suffer different distortions at the same time.
Brick forming may be the cause of multiple distortions.
Lastly, brick over-burn at the base of the clamp cause multiple distortions as well.
Fig.21: defects in brick shape, multiple distortions
OR
Various defects in bricks
The various defects in bricks are explained as follows.
1. Over burning of bricks: - Burning of bricks should be done at temperature at which complete
vitrification occurs. If bricks are over burnt, a molten mass(soft) is produced and bricks lose
their shape. Such types of bricks are not used in construction.
2. Burning of bricks: - When bricks are burnt but complete vitrification does not occur. Then
such type of defect is known as under burning of bricks. Due to lesser amount of heat, the clay
is not softened and the pores are not closed. It leads to less compressive strength and higher
degree.

55 | P a g e
SAQIB IMRAN 0341-7549889 55
3. Efflorescence: - Presence of alkalis in bricks causes this defects in bricks. When bricks come
in contact with moisture water is absorbed and the alkalis crystalise. Grey or white spots
appear on the surface of bricks after drying. This defect can be reduced by proper selection of
clay materials for manufacturing of bricks, preventing moisture to come in contact with the
masonary and by providing damp proof course.
4. Black core: - When brick clay contains bituminous matter or carbon and they are not
completely removed by oxidation, the brick converts in black core because of improper
burning.
5. Chuffs: - The deformation of the shape of bricks caused by the rain water falling on hot bricks
is chuffs.
6. Blisters: - Broken blisters are generally caused on the surface of sewer pipes and drain tiles
due to air imprisoned during their moulding.
7. Laminations: - These are caused by entrapped air in the voids of clay. Laminations produce
thin lamina on the brick faces, which weather out on exposure. Such bricks are weak in
structure.
Tests on Bricks
The following laboratory tests may be conducted on the bricks to find their suitability:
(i) Crushing strength
(ii) Absorption
(iii) Shape and size and
(iv) Efflorescence.
(i) Crushing Strength: The brick specimen is immersed in water for 24 hours. The frog of the
brick is filled flush with 1:3 cement mortar and the specimen is stored in damp jute bag for 24
hours and then immersed in clean water for 24 hours. The specimen is placed in compression
testing machine with 6 mm plywood on top and bottom of it to get uniform load on the
specimen. Then load is applied axially at a uniform rate of 14 N/mm2 . The crushing load is
noted. Then the crushing strength is the ratio of crushing load to the area of brick loaded.
Average of five specimen is taken as the crushing strength.
(ii) Absorption Test: Brick specimen are weighed dry. Then they are immersed in water for a
period of 24 hours. The specimen is taken out and wiped with cloth. The weight of each
specimen in wet condition is determined. The difference in weight indicate the water absorbed.
Then the percentage absorption is the ratio of water absorbed to dry weight multiplied by 100.
The average of five specimens is taken. This value should not exceed 20 per cent.
(iii) Shape and Size: Bricks should be of standard size and edges should be truely rectangular
with sharp edges. To check it, 20 bricks are selected at random and they are stacked along the
length, along the width and then along the height. For the standard bricks of size 190 mm × 90
mm × 90 mm. IS code permits the following limits:
Lengthwise: 3680 to 3920 mm
Widthwise: 1740 to 1860 mm
Heightwise: 1740 to 1860 mm.

56 | P a g e
SAQIB IMRAN 0341-7549889 56
The following field tests help in acertaining the good quality bricks:
(i) uniformity in size
(ii) uniformity in colour
(iii) structure
(iv) hardness test
(v) sound test
(vi) strength test.
(i) Uniformity in Size: A good brick should have rectangular plane surface and uniform in size.
This check is made in the field by observation.
(ii) Uniformity in Colour: A good brick will be having uniform colour throughout. This
observation may be made before purchasing the brick.
(iii) Structure: A few bricks may be broken in the field and their cross-section observed. The
section should be homogeneous, compact and free from defects such as holes and lumps.
(iv) Sound Test: If two bricks are struck with each other they should produce clear ringing
sound. The sound should not be dull.
(v) Hardness Test: For this a simple field test is scratch the brick with nail. If no impression is
marked on the surface, the brick is sufficiently hard
(vi) Efflorescense: The presence of alkalies in brick is not desirable because they form patches
of gray powder by absorbing moisture. Hence to determine the presence of alkalies this test is
performed as explained below:
Place the brick specimen in a glass dish containing water to a depth of 25 mm in a well
ventilated room. After all the water is absorbed or evaporated again add water for a depth of
25 mm. After second evaporation observe the bricks for white/grey patches. The observation is
reported as ‘nil’, ‘slight’, ‘moderate’, ‘heavy’ or serious to mean
(a) Nil: No patches
(b) Slight: 10% of area covered with deposits
(c) Moderate: 10 to 50% area covered with deposit but unaccompanied by flaking of the
surface.
(d) Heavy: More than 50 per cent area covered with deposits but unaccompanied by flaking of
the surface.
(e) Serious: Heavy deposits of salt accompanied by flaking of the surface.
Chapter No 2
Aggregates:
It is defined as: “Aggregates are the inert materials that are mixed in fixed proportions with
a Binding Material to produce concrete “.
These act as fillers or volume increasing components on the one hand and are responsible for
the strength, hardness, and durability of the concrete on the other hand.

57 | P a g e
SAQIB IMRAN 0341-7549889 57
Qualities of Aggregates.
Following are the most important qualities of an Aggregate.
1. It should be chemically inert, i.e., they should not react with cement or any other aggregate
or admixture.
2. It should possess sufficient hardness to resist scratching and abrasion in the hardened state.
3. It should possess sufficient toughness to bear impact and vibratory loads.
4. It should be strong enough to bear compressive and normal tensile loads in the ordinary
mixture.
5. It should be free from impurities, inorganic or organic in nature, which will affect adversely
on its quality.
6. It should be capable of producing an easily workable plastic mixture on combining with
cement and water.
Aggregate Classification | Types of Aggregates.
Aggregates are variously classified on the basis of their grain size, their origin, and their volume-
weight as follows:
(1.) Aggregate Types on the basis of Grain Size.
This is the most common classification, where in two types of aggregates are
distinguished: (Fine and Coarse).
(i) Fine Aggregates.
In the Fine Aggregates, the grain-size lies between 4.75 mm and 0.15 mm.
In other words, these pass-through from sieve with the mesh size of 4.75 mm and are retained
on a sieve of 0.15 mesh size. Sand is the most universally available natural Fine Aggregate.
(ii) Coarse Aggregates:

58 | P a g e
SAQIB IMRAN 0341-7549889 58
Coarse aggregates are those that are retained on the sieve of mesh size 4.75 mm.
Their upper size is generally around 7.5 mm.
Gravels from river bed are the best coarse aggregates in the making of Common Concrete.
In those situations, if they are not easily available, Suitable rock types are crushed to the
desired particle sizes for making coarse aggregates.
(2.) Types on the Basis of origin.
There are three types on the Basis of Origin.
(i) Natural:
These include all those types of fine and coarse aggregates, that are available in almost ready to
use form, from natural resources.
Examples are sands from river beds, pits and beaches, and gravels from river banks.
(ii) Bye-product:
These include materials obtained as wastes from some industrial and metallurgical engineering
operations, which possess suitable properties for being used as aggregate.
Examples: Cinder obtained from burning of coal in locomotives and kilns.
And Slag is obtained from blast furnaces as Scum is the best example from this category.
(iii) Processed:
These form a special class in Aggregate. They are specifically manufactured for use in
making Quality Concretes.
Examples: They include burnt clay, Shales, vermiculite’s and perlite. They are
essential Ingredients of Lightweight Concrete.
(3.) Types on the Basis of Density.
Three types of aggregates are distinguished on the basis of their weight per unit volume.
(i) Standard or Normal:
These types of aggregates give strength and weighting to the Concrete of around 2300 to 2500
kg/m3.

59 | P a g e
SAQIB IMRAN 0341-7549889 59
Gravels, Sand and Crushed stone, are all classed as Standard or Normal Aggregates.
(ii) High-Density Aggregates:
These are that type of Aggregates, which is used in standard proportions yield in heavy weight
concretes.
Such concretes are especially useful as shields against X-rays and radiations in the atomic
power plant.
Examples: Baryle – a natural mineral with a specific gravity of 4.3 is an example.
Concretes with such aggregate usually weight above 4000 kg/m3.
(iii) Light weight Aggregate:
They consist of natural and artificial materials of very low density so that the resulting concrete
is also quite Light in weight, generally with in a range of 350 to 750 kg/m3.
They are specially used in sound proofing and fire proofing constructions.
They are also used extensively in the manufacture of light weight Pre-Cast concrete blocks.
Physical Properties of Aggregete
Aggregate is the principle ingredient that is used in construction. The physical
properties of mineral aggregates are those that are used in reference to the physical
structure of particles that the aggregate consists of.
Absorption, Porosity and Permeability:
An important property of aggregates is the internal pore characteristics. What make up
this characteristicare the absorption, porosity and permeability of the aggregate. The size,
number and continuity of the pores has an effect on its strength, its resistance to
abrasion, texture of the surface, gravity, bonding capabilities as well as its resistance
to freezing and thawing. The ratio of the volume of the pores to the total volume of the particle
is what makes up the porosity. Absorption is the particle’s ability to absorb water. Permeability
is the particle’s ability to let water pass through it.
Texture of the Surface:
The pattern and the roughness or smoothness of the aggregate is the surface texture. It plays a
substantial role in creating a bond between the aggregate and the cementing material. For
example, when the surface of an aggregate has a rough texture, it gives the cementing
material something to grip and this produces a stronger bond. The texture of the surface also
plays a role in the workability of hot mix asphalt, how much asphalt is required for the hot mix
and the water requirements in cases where portland cement concrete is being used.
Strength and Elasticity:
The strength of an aggregate is measured in terms of its ability to endure forces that may push
or crushwhile it is being used. Elasticity refers to how much the particle can stretch. High levels

60 | P a g e
SAQIB IMRAN 0341-7549889 60
of both these properties are required in the base and surface. The rate at which the concrete
disintegrates is minimized while the stability of the compacted material is maximized by these
properties.
Density and Specific Gravity:
The weight per unit of volume of a substance makes the density while specific gravity is the
ratio of the density of the substance to the density of water. The density and the specific gravity
of an aggregateparticle depend on the density and specific gravity of the minerals making up
the particle and also on how porous the particle is.
Voids in the Particles:
Voids are natural pores that are present in the aggregate particles. These pores are filled with
air and water. These voids affect the specific gravity as well as the absorption of
the aggregates. They may not be visible but most aggregates have pores. The voids that are
present between the particles have an effect on the design of hot mix asphalt or portland
cement concrete.
Hardness of the Minerals:
The resistance of the aggregate to abrasion and degradation is controlled by the hardness of
the minerals which the aggregate particles are made up of and the firmness with which the
grains of the particles are cemented or locked together. Minerals that have a low degree
of hardness compose soft aggregate particles. The weaker the particles are, the poorer the
cementation is.
Shape of the Particles:
The shape of the aggregate particles affects the workability and strength of both portland
cement concrete and hot asphalt mixes. It also has an effect on how much asphalt is needed for
the mix. Crushedstone or crushed gravel are considered to be the best types of aggregates to
use for strength. When crushed aggregates that have irregular or angular particles are used,
they interlock or bind closer when they are compacted or consolidated.
Crushed stone or gravel aggregates make the asphalt or concrete mix difficult to place. To make
them easier to work with, both angular and round particles are used in many mixes.
Aggregate Particle Coatings:
There is a layer that covers the entire or part of the surface of an aggregate which is known as
a coating. The coating may be natural, like mineral deposits that are formed in sand
or gravel by ground water. It could also be artificial like dust that is formed by crushing and
handling of the particles.

61 | P a g e
SAQIB IMRAN 0341-7549889 61
Generally, it is required that aggregates are washed to remove the coating that is left on the
particles. This is necessary as the coating could prevent a good bond to form between
the aggregate surface and the cementing agent. The bonding agent that is required in
the mixture could also increase due to these coatings.
In the future, it is thought that aggregates will be supplied more from recycled or waste
materials. To make sure that there is no decrease in the quality and performance of the
products, the challenge will be to process and test these materials. The goal would be to make
sure that such materials have the fundamental chemical,
physical, and mechanical characteristics that guarantee high performance and workability.
Propertise of Good Sand
Good sand should be pure silica. It should be free from clay, salt, silt and organic matters. It is
better wash sand before construction work.
Sand is one of the important constituents of concrete. The main purpose of mixing sand (fine
aggregate) in concrete is to fill the voids between Coarse aggregate. And the voids between fine
aggregate is filled with cement. Sand bulks the concrete and helps to increase the workability of
concrete.
Sand is formed by the weathering of rocks. Well, different regions use the variety of sands (Pit
sand, River sand, Sea Sand) in construction according to the availability. A good fine aggregate
should be well graded (all particles that have almost same size).
The fine aggregate used for construction should pass 4.75mm sieve and retain on 150microns
sieve.
Below mentioned tests are the simple tests which you can perform quickly on site to find out
the quality of Sand. These tests include checking the properties of Sand which affect the
strength and the quality.
Tests for finding quality of sand on site: -

62 | P a g e
SAQIB IMRAN 0341-7549889 62
Excessive clay / Silt:-
Presence of clay in Sand makes the sand cohesive, the good quality of sand should have less
percentage of clay in it.
Presence of excessive clay can be determined in two ways:-
1. For testing presence of clay in the sand, take a glassful of water and add some sand to it.
Shake it vigorously and allow the sand to settle. Check whether an apparent layer is
formed on the sand. A good quality of sand should have less than 8% of clay in it.
2. Hold some dry sand and drop it. If the Sand adheres to your palm, then it has Clay.
Presence of Organic Impurities in Sand: -
For detecting the presence of Organic impurities in fine aggregate. Take a Sample of sand and
add it in Sodium Hydroxide [NaOH] Solution, Stir the solution for few minutes, if the color of
solution changes to brown, then the sand has organic impurities which are not suitable for
construction. Good quality of sand shows lighter color when it is mixed with NaOH solution.
Presence of Excessive moisture content / Bulking of Sand: -
Presence of excessive moisture content in sand causes increase in the volume of sand. Fine
Aggregate Which contains more than 5% of moisture content in its volume is not suitable for
construction purposes.
For accurate conclusions, fineness modulus test and silt content by weight are suggested for
large projects
What is Bulking of Sand | Its Classification & How to Calculate it?
Sand is an important construction material of natural origin, mixed with cement and lime,
millions of tons of sands are used every month for construction as mortars, plasters, and
concrete.
The term sand is used for rock particles that range in grain size between 2 mm and 1/16 mm. In
composition, they are predominantly an oxide of silica SiO2.
Mineralogically, they consist mostly of broken grains of mineral Quartz (SiO2) produced as a
result of the breakdown of sandstones and similar rocks.
We will discuss below in details Classification and Bulking of Sand. So Let’s move on:
Classification of Sand.
Sands are classified variously on the basis of their mode of origin, their composition, and their
grain size.
Classification of Sands according to the mode of origin:
According to the mode of origin, sands are of three types, namely, pit sands, stream
sands and marine sands.

63 | P a g e
SAQIB IMRAN 0341-7549889 63
The pit sands are generally sharp and angular in outline. Winds usually deposited them and
form accumulations in soils that may be covered by clays. These sands, when cleaned and
washed, make good mortars.
The river sands occur as accumulations of great extent along the base and banks of all the rivers
in plains and semi-hilly areas. The shape of the sand grains in river sands is almost round (due
to considerable transport in river waters).
These are generally free from clay, salt encrustations, and organic impurities. Hence, these are
the most commonly used sand for making mortars, plasters, and concrete.
The marine sands occur on beaches and along the seashores. Like river sands, they consist of
rounded grains of quartz. A common difficulty with these sands is that their grains are often
covered with coatings of salts from sea water.
These salts are not easily separable. Hence, if used in mortars or concrete, the salts react with
the binding materials creating a lot of difficulties. Moreover, the salt encrustations are often
hygroscopic, i.e., they absorb moisture from the atmosphere.
This also results in delayed setting, dampness and efflorescence may also occur in mortar
or concrete made with these sands. Hence, marine sands are considered of inferior quality and
should be better avoided. When these become the only source available, marine sands must be
thoroughly washed before use.
Classification of Sand according to its composition:
According to composition, following three categories of sand are recognized in engineering
fields.
Clean sands: These are well-graded sand containing entirely or mostly quartz (SiO2) particles in
a wide range of grain size.
Silty sands: These are poorly graded sands which have a considerable proportion of silt (particle
size between 0.625 to 0.075 mm) and other non-plastic fines.
Clayey Sands: These are poorly graded sands having a prominent clay fraction (particle size
below 1/256 mm) and also plastic fines.
Obviously, for use in making mortars, plasters, and concrete. Clean sands must only be used.
Sand is also obtained artificially by crushing natural quartzite rock to the required grain size.
Classification of Sand according to its grain size:
According to grain-size, sand is classified as coarse. medium and fine sand: 2 – 1 mm, 1 – 0.25
mm, 0.25-0.15 mm, respectively.
Bulking of Sand:
Bulking of sand is an important volumetric change that takes place in sands when they are
moist. Sands increase in volume, to the extent of 20-30 percent, when they contain moisture
between 2-8 percent.
This is because moisture in small proportions forms thin films around the sand grains.
Fine sands bulk greater than coarse sand. When the moisture content is increased beyond 8-10
percent, the bulking of sand effect almost disappears. In fact, sand grains settled in a water
tank will have the same volume as dry sand.

64 | P a g e
SAQIB IMRAN 0341-7549889 64
The quality of sand is determined concerning its clay content, contamination with organic
impurities and its salt encrustations. Good quality sands should be free from all these
impurities.
It is established that volume of sand will be more when water is present in it even in small
quantities. In other words, two batches of sand, one dry and one moist, that may have the
same weight, will have different volumes. The volume of moist sand will be more than that of
dry sand.
This change (increase) in the volume of sands on getting moist is termed as bulking of sand.
Full knowledge of bulking of sand is necessary for a construction engineer because sand is
sometimes used for mortars, plasters, and concrete by volume.
All the mix designs denote the proportion of sand is essentially in the dry state.
As such if this fact is ignored and sand in wet condition is added to the cement or lime, the
resulting mortar will be containing a lesser amount of sand than the required amount.
Hence, a correction factor for bulking of sand has to be applied alter-determining the rate of
bulking for the sand to be used in mortar and concrete making.
As regards the rate of bulking of sand, it has been observed that it is related to two factors.
(i) percentage of moisture content in the sand.
(ii) Gram-Size of the sand particles.
Thus, bulking effect is maximum when moisture content in the sand is between 4-6 percent. As
the water-content increases, this effect goes on decreasing, becoming negligible at 15-20 per
cent moisture content.
Similarly, other things being same, the fine sands (particle size 0.25 to 0.15 mm) show higher
bulking rate as compared to the coarse sands (particle size around 2 mm).
Bulking may be to the extent of 40 percent of the original dry volume of sand in the fine and 15
percent in the case of coarse sands.

65 | P a g e
SAQIB IMRAN 0341-7549889 65
How to Calculate Bulking of Sand?
A quick method to determine bulking of sand of given sample containing some moisture is as
follows:
(Step-1): Take a clean glass cylinder and fill it about 3/4 with the sand sample. Then, Note down
its volume. Let’s Say; it’s Volume = V1= is 30 cm3.
(Step-2): Now carefully take the sand out and place it on a glass plate. Fill the glass cylinder
with water to 3/4 of its volume.
(Step-3): Put the sand sample back into the glass cylinder very slowly, Stirring the water while
adding sand into it. This is essential to make all the sand grains settle fully in the cylinder.
Note down the new volume of sand sample Let it be V2.
(If V2 = V1, it means that the sand samples have retained to its original volume, i.e., it has shown
no bulking).
But Let’s say in another case V = 24 cm. Then bulking of sand sample will be: V1-V2/V1 x 100.
Now just put the values of V1 = 30 cm3 and V2 = 24 cm3.
So, Now 30-24/30 x 100 => 6/30 x 100 => 20%.
So, this means that 20% of bulking of sand has taken place.

66 | P a g e
SAQIB IMRAN 0341-7549889 66
Test Procedure to Determine the Bulking of Sand
Following steps can be followed to calculate the percentage of bulking of sand in a given
sample-
1. Fill the measuring cylinder with the sample up to 200 ml mark.
2. For accurate measurement steel scale can be used, but no compaction of sand is
allowed.
3. The sand is to be transferred to a container.
4. The measuring cylinder is refilled with 100ml water.
5. The measuring cylinder should be refilled with sample sand and stirred with a steel rod.
6. Give some time so that the sand can settle.
7. The level of sand will be below the 200ml mark this time. Let the present level be “a.”
8. So the bulking of sand for this sample will be determined by the following equation-
BulkingofSand=200−aa×100BulkingofSand=200−aa×100
9. The procedure should be repeated twice and the average value of the tree observation
will be the percentage of bulking of sand for the given sample.
PROPERTIES AND TESTING OF AGGREGATES FOR PAVEMENT WORKS
Aggregates plays vital role in the construction of pavement. They have great capability of load
transfer to the Subgrade soil. Aggregates have different properties which are tested individually
with different types of tests for the construction of pavement.

67 | P a g e
SAQIB IMRAN 0341-7549889 67
Aggregate should qualify all the tests conducted to give better results after construction. The
properties of aggregate and their respective tests are given below.
Properties and Tests of Aggregates for Pavement Works
Aggregate Property Test to be conducted
strength Crushing strength test
Hardness
Abrasion test
Impact value Impact test
Resistance against weathering Soundness Test
Shape of aggregate Shape test
Bitumen adhesion Bitumen Adhesion test

68 | P a g e
SAQIB IMRAN 0341-7549889 68
Specific gravity Specific gravity test
Water absorption Water absorption test
Crushing Strength Test on Aggregates
Aggregate crushing value gives the Crushing strength of aggregate up to which it
can bear the load without fail. To conduct crushing strength test we need
compression testing machine, cylindrical measure, plunger and Isa sieves.
First sieve the sample aggregate, aggregate passing 12.5mm sieve and retaining
10mm sieve is oven dries at 100-110o
C for 3-4 hrs. The cylinder is filled with
aggregate in 3 layers, 25 strokes of tampering for each later. Note down its
weight and insert the plunger and placed it on compression testing machine.
Apply the load at uniform rate of 40 tonnes load in 10 minutes. Then stop the
machine and crushed aggregate is sieved through 2.36mm sieve and aggregate
passing 2.36mm sieve is weighed.
Aggregate crushing value can be obtained from below formula:
Aggregate crushing value = (W2/W1) *100 %

69 | P a g e
SAQIB IMRAN 0341-7549889 69
Abrasion Test on Aggregates
Hardness property of aggregate is determined by conducting abrasion test. Los
Angeles abrasion testing machine is used to conduct this test.
For this test, the sample taken should be clean and dried. The sample is weighed
W1 and placed in Los Angeles testing machine and the machine is operated.
Machine should be rotated at a speed of 20-33 revolutions per minute. After 1000
revolutions the sample is taken out and sieved through 1.7mm sieve. Sample
retained on 1.7mm is washed and dried and note down its weight W2.
Aggregate abrasion value = {(W1-W2)/W2} x 100%
Impact Test on Aggregates
Impact value of aggregate will give aggregate capability against sudden loads or
forces. For this test also aggregate passing through 12.5mm and retained on
10mm sieve is taken and oven dried.
Fill the cylinder with aggregate in 3 layers, 25 strokes of tamping for each layer.
Weight w1 noted. The cylinder is placed in impact testing machine which consist
a hammer. After placing the cylinder, hammer is raised to 380mm and release
freely. Then it will blow the aggregates. Repeat it for 15 such blows. After that
take down the sample and aggregate passing through 2.36mm sieve is weighed
as w2.

70 | P a g e
SAQIB IMRAN 0341-7549889 70
Aggregate impact value = (W2/W1) *100 %
Soundness Test on Aggregates
To determine the weathering resistance of aggregate soundness test is
conducted. If the resistance against weathering is good for aggregate, then it will
have high durability.
For soundness test we need some chemical solutions namely sodium sulphate or
magnesium sulphate. The sample of aggregate passing through 10mm sieve and
retained on 300 micron sieve is taken. Dry and weigh the sample and immerse
them in the chemical solution for about 18 hours. After that, Take the sample and
dried it in oven at 100 -110o
c. repeat this procedure 5 times for one sample, and
weigh the aggregate finally and note down the difference in weight loss.
The weight loss should be below 12% if sodium sulphate is used, below 18% if
magnesium sulphate is used.

Materials & Methods of Construction - CE145

Materials & Methods of Construction - CE145

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Materials & Methods of Construction - CE145

Similar to Materials & Methods of Construction - CE145 (20)

More from Saqib Imran

More from Saqib Imran (20)

Recently uploaded

Recently uploaded (20)

Materials & Methods of Construction - CE145