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WHAT IS BRICK?
A brick is building material used to make walls, pavements and
other elements in masonry construction.
Traditionally, the term brick referred to a unit composed of clay,
but it is not used denote any rectangular units laid in mortar.
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Bricks are made chiefly from clay and shale.
Clay is plastic earth, is constituted largely of sand an alumina
and may contain various quantities of chalk, iron, manganese,
dioxide, etc.
Shale is soft finely stratified sedimentary rock that formed
from consolidated mud or clay and can be split easily into
fragile plates
Shale Clay
INTRODUCTION
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Good bricks should be thoroughly burnt, this makes them hard and durable
A hard ringing sound emitted when two bricks are stuck together indicates that they have been brunt
satisfactorily.
CHARACTERISTICS OF BRICKS
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Bricks should be true to size and shape, with straight edges and even
surfaces.
They should be free from cracks, chips, and larger particles of lime.
Brick when broken should show a bright homogeneous and compact
structure free from voids.
No impression should be left on brick surface when it is scratched with
finger nail.
Brick should not break when dropped flat on hard ground from a height
CHARACTERISTICS OF BRICKS
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Absorption
Water absorption is brick is carried out by immersing it in water
for 24 hours.
It is again weighed and the different is in indicated the amount of
water absorbed by brick.
It should not in any case exceed 20% of wet of dry bricks.
TEST ON BRICK
Crushing Strength
Crushing strength of brick is found out by placing it in compressive
test machine.
It is pressed till it breaks
The minimum crushing strength of brick is 55kg/cm2
In this test, a stretch is made on brick surface with the help of
finger nail.
If no impression is left on surface, the brick is treated to be
sufficiently hard.
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Presence of soluble salts
The soluble salts, if present in bricks will cause efflorescence in the surface of bricks.
For finding out the presence of soluble salts in a brick, it is immersed in water for 24 hrs.
TEST ON BRICK
Soundness
In this test, two bricks are taken and than struck together with each other, the bricks should not
break and a clear ringing sound should be produced.
Structure
A brick is broken and its structure is examined.
It should be homogeneous, compact and free from any defects.
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Colour
Texture
Porosity
Fire resistance
Compressive strength
PROPERTIES OF BRICKS
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Burnt bricks Unburnt bricks
First class bricks
Second class bricks
Third class bricks
Fourth class bricks
Bricks used in construction works are burnt bricks and they
are classified into the following four categories.
CLASSIFICATION OF BRICKS
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First class bricks:
These bricks are table- moulded and of standard shape.
The surfaces and edges of the bricks are sharp, square, smooth
and straight.
They complete with all the qualities of good bricks.
These bricks are used for superior work of permanent nature.
These bricks gives metallic sound when stuck together.
After immersing the brick in water for 24 hours, water
absorption should not be more than 15 per cent by weight.
CLASSIFICATION OF BRICKS
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Second class bricks:
These bricks are ground moulded and they are burnt in kilns.
The surface of these bricks is some what rough and shape is also
slightly irregular.
These bricks are commonly used at places where brickwork is to
be provided with a coat of plaster.
After immersing the brick in water for 24 hours, water absorption
should not be more than 20 per cent by weight.
CLASSIFICATION OF BRICKS
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Third class bricks:
These bricks are ground moulded and they are burnt in clamps.
These bricks are not hard and they have rough surfaces with
irregular and distorted edges.
These bricks gives dull sound when stuck together.
They are used for unimportant and temporary structures and it
places where rainfall is not heavy.
CLASSIFICATION OF BRICKS
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Fourth class bricks:
These bricks are used as aggregate for concrete in foundation,
floors, roads etc.
These bricks are over burnt with irregular shape and dark in
colour.
Because of the fact that the over burnt bricks have a compact
structure and hence, they are sometimes found to be stronger
than even the first class bricks.
CLASSIFICATION OF BRICKS
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ADVANTAGES OF BRICKS DISADVANTAGES OF BRICKS
Better thermal insulation Time consuming construction
Economical Cannot be used in high seismic zones
Masonry is easier, faster and stronger Very less tensile strength
Bricks have greater fire resistance Since bricks absorbs water easily, therefore it
causes fluorescence when not exposed to air
Its size enables easy handling and placement in walls. Rough surfaces of bricks may cause mould growth
if not properly cleaned
It can be easily adapted to small scale and large scale
structure to give pleasing appearance and texture.
It enhances good sound absorption
Very low maintenance cost is required
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2. Curved sector bricks: these bricks are in the form of curved sector and they are used in the
construction of circular brick masonary, pillars, brick chimneys.
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3. Channel bricks: these bricks are moulded to the shape of a gutter or a channel and they are
very often glazed. These bricks are used to function as drains.
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4. Coping bricks: these bricks are made of suit the thickness of walls on which coping is to be provided.
Such bricks take various forms such as chamfered, half round or saddle-back.
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5. Bull nose bricks: A brick moulded with a rounded angle is termed as a bull nose. It is used for a
rounded quoin.
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6. Hollow bricks:
These are also known as cellular or cavity bricks.
Such bricks have wall thickness of about 20 cm to 25cm.
They are prepared from special homogeneous clay.
They are light in weight about one-third the weight of the ordinary brick of the
same Size.
These bricks can be laid almost about four times as fast as they ordinary bricks
and thus the use of such bricks leads to speedy construction.
They also reduce the transmission of heat, sound and damp. They are used in the
construction of brick partitioning.
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7. Paving bricks:
These bricks are prepared from clay containing a higher
percentage of iron.
Excess iron vitrifies the bricks at a low temperature.
Such bricks resists better the abrasive action of traffic.
Paving bricks may be plain or chequered.
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8. Perforated bricks:
These bricks contain cylindrical holes throughout their thickness.
these bricks are light in weight and they require less quantity of clay for their
preparation.
The dying and burning of these bricks are also easy.
The perforated bricks are used in the construction of brick panels for light
weight structures and multistoried framed structure.
The perforation may be circular, square, rectangular or any other regular shape
in cross section.
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9. Purpose-made bricks:
In order to achieve certain purpose, these bricks are made.
The arch brick are made of wedge shape to keep mortar joint of
uniform thickness.
The ornamental brick are prepared for corbels, cornices.
The gutter bricks are used to construct gutter.
The plinth bricks are used to emboss the plinth level.
These bricks are usually more costly than the ordinary bricks but
they grant safe,
clean and quick construction.
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10. Queen closer bricks:
The queen closer is usually placed next to the first brick in header course. The
queen closer-1/2 is obtained by cutting an ordinary brick into half bats and then
splitting one into half.
The queen closer quarter is more often used than queen closer-half as it is
easier to cut, all though it is generally produced a 56mm wide continuous
vertical joint.
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Following factors affect the strength of bricks:
Composition of brick earth
Preparation of clay and blending of ingredients
Nature of moulding adopted
Care taken in drying and stacking of raw or green bricks
Type of kiln used including type of fuel and its feeding
Burning and cooling processes
Care taken unloading
STRENGTH OF BRICKS
34. Types of Bond
Header Bond
Stretcher Bond
English Bond
Flemish Bond
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BRICK BONDS
Stretcher Bond
Originally used for single brick walls, it
became the obvious choice for cavity walls
with the least amount of cutting required.
It is therefore the most economical bond
pattern and is extensively used in modern
building.
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BRICK BONDS
Header Bond
A brick course laid flat with the short end
of the brick exposed. This method is
particularly strong as the width of the wall
is the whole length of a brick. Historically
it was used for buildings of high quality,
often used for curved brickwork.
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BRICK BONDS
English Bond
It comprises of alternative courses of
headers and stretchers. It provides a
strong bond when the wall is one brick
thick. It is the preferred bonding pattern
for bridges, viaducts, embankment walls
and other civil engineering architectures
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BRICK BONDS
Flemish Bond
Flemish bonds can be replicated in the
half-brick outer leaf of a cavity wall by
using whole bricks as stretchers, while the
headers are created by half bricks called
bats or snap-headers. It is not as strong as
English bond at one brick thick.
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The length of brick should be twice its width plus the thickness of one
vertical joint in order that a proper bond may be maintained. Brick in
common use vary in size from 210 to 230mm long by 100 to 115 mm wide
by 38 to 75 mm thick.
Clay bricks are mostly 230 X 115 X 75 mm, using a 10mm joint this gives a
nominal size or format of 240 X 125 X 85 mm.
BRICKS
