Manufacturing, types, brick bonds, defects

1. BRICKS
BY
RIMPI BARO
LECTURER, CIVIL ENGINEERING DEPARTMENT
PANDIT DEENDAYAL PETROLEUM UNIVERSITY,
GANDHINAGAR
BUILDING MATERIALS AND CONSTRUCTION

2. A brick is a man-made building material used to
make walls and make places to walk. It is a single unit
of a kneaded clay-bearing soil, sand and lime,
or concrete material, fire-hardened or air-dried, used
in masonry construction.
Bricks are made mostly of clay. They are put
into moulds or cut with wires, and then baked in
an oven. The colour of a brick depends on the clay from
which it was made.

3. BRICKS
COMPOSITION
• Alumina: - A good brick earth should contain 20 to 30
percent of alumina. This constituent imparts plasticity to
earth so that it can be moulded. If alumina is present in
excess, raw bricks shrink and warp during drying and
burning.
• Silica-A good brick earth should contain about 50 to 60
percent of silica. Presence of silica prevents cracks, shrinking
and warping of raw bricks. It thus imparts uniform shape to
the bricks Excess of silica destroys the cohesion between
particles and bricks become brittle.
• Lime – A small quantity of lime is desirable in finely
powdered state to prevents shrinkage of raw bricks. Excess
of lime causes the brick to melt and hence, its shape is lost
due to the splitting of bricks.

4. • Oxide of iron- A small quantity of oxide of Iron to the extent of 5 to 6
percent is desirable in good brick to imparts red colour to bricks. Excess of
oxide of iron makes the bricks dark blue or blackish.
• Magnesia- A small quantity of magnesia in brick earth imparts yellow tint
to bricks, and decreases shrinkage. But excess of magnesia decreases
shrink leads to the decay of bricks.
• The ingredients like, lime, iron pyrites, alkalies, pebbles, organic matter
should not present in good brick earth

5. – Qualities of Good Brick:
• Bricks should be table well burnt in kilns, copper coloured,
free from cracks and with sharp and square edges.
• Bricks should be uniform shape and should be of standard
size.
• Bricks should give clear ringing sound when struck each other.
• Bricks when broken should show a bright homogeneous and
compact structure free from voids.
• Bricks should not absorb water more than 20 percent by
weight for first class bricks and 22 percent by weight for
second class bricks, when soaked in coldwater for a period of
24 hours.

6. MANUFACTURE OF BRICKS
• The following operations are involved
1.Preparation of clay
2. Moulding
3.Drying
4.Burning

7. 1. Preparation of clay :- The preparation of clay involves following
operations
Unsoiling :- Top layer of 20cm depth is removed as it contain impurities.
Digging: - Clay dug out from ground is spread on level ground about 60cm
to 120cm heaps.
Cleaning:-Stones, pebbles, vegetable matter etc removed and converted
into powder form. if large quantity of particulate matter is present, then
the clay is washed and screened. The lumps of clay are converted into
powder with earth crushing rollers.
Weathering:- Clay is exposed to atmosphere from few weeks to full
season.
Blending:- Clay is made loose and any ingredient to be added to it is
spread out at top and turning it up and down in vertical direction.
Tempering:- Clay is brought to a proper degree of hardness, then water is
added to clay and whole mass is kneaded or pressed under the feet of
men or cattle for large scale, tempering is usually done in pug mill.

9. Tempering
Pug mill

10. Moulding: Clay, which is prepared form pug mill, is sent
for the next operation of moulding. Following are the
two ways of moulding.
Hand Moulding and Machine moulding

11. Hand Moulding:
• If manufacturing of bricks is on a small scale and manpower is
also cheap then we can go for hand moulding. The moulds are
in rectangular shape made of wood or steel which are opened
at the top and bottom. The longer sides of moulds are
projected out of the box to serve it as handles. If we take
durability in consideration steel moulds are better than
wooden moulds. In hand moulding again there are two types
and they are
• Ground moulded bricks
• Table-moulded bricks

12. Ground moulded bricks
• In this process of ground moulding, first level the ground and sand or ash
is sprinkled over it.
• Now place the wet mould in the ground and filled it with tempered clay
and press hard to fill all corners of the mould. Extra clay is removed with
metal strike or wood strike or with wire.
• The mould is then lifted up and we have raw brick in the ground. And
again wet the mould by dipping it in water and repeat the same process.
The process of dipping mould every time to make bricks is called slop
moulding.
• Sometimes, the inside surface of mould is sprinkled with sand or ash
instead of dipping in water this is called sand moulding
• Frog mark of bricks are made by using a pair of pallet boards. Frog mark
means the mark of depth which is placed on raw brick while moulding.
The depth may be 10mm to 20mm.
• Frog mark stats the trademark of manufacturing company and also it is
useful to store mortar in it when the bricks is placed over it.

15. Hand moulding on the table: Here the moulding is
done on the table which is generally of the size 2 m *
1m. It may take somewhat longer time than the
ground moulding.

16. • Machine moulding: This method proves to be economical
when bricks in huge quantity are to be manufactured at the
same spot. It is also helpful for moulding hard clay
• Here also we are having two types of machines,
• Plastic clay machines
• Dry clay machines

17. • Plastic clay machines This machines contain an opening in
rectangular shape and when we place the tempered clay in to
this machine it will come out through this opening. Now, the
rectangular strips coming out the opening are cut by wires to
get required thickness of brick. So, these are also called wire
cut bricks. Now these raw bricks are ready for the drying
process.
• Dry clay machines Dry clay machines are more time saving
machines. We can put the blended clay into these machines
directly without tempering. Means tempering is also done in
this machine by adding some water. When the required
stiffness is obtained the clay is placed in mould and pressed
hard and well-shaped bricks are delivered. These are called
pressed bricks and these do not require drying they may
directly sent to burning process.

18. Plastic clay machine

19. Dry clay machine

20. 3. Drying:
The damp bricks, if burnt, are likely to be cracked and distored.
Hence moulded bricks are dried before they are taken for the
next operation of burning. Bricks are laid along and across the
stock in alternate layers. The drying of brick is by the following
means
• The bricks are laid in stacks. The bricks in these stacks should
be arranged in such a way that circulation of air in between
the bricks is free.
• The period of drying may be 3 to 10 days. It also depends
upon the weather conditions.
• The drying yards are also prepared on higher level than the
normal ground for the prevention of bricks from rain water.
• In Some situations artificial drying is adopted under special
dryers or hot gases.

22. Artificial Drying: In artificial burning bricks are put under a
temperature of about 120 degrees Celsius in a tunnel like
structure where arrangements are there to maintain the
temperature.
These tunnel kilns can be period or continuous. In periodic
kilns the bricks are dried periodically but in the continuous
they are put continuously at one end and dried bricks are
taken out at the other end.

23. Artificial drying

24. 4. Burning of Bricks
The burning of clay may be divided into three main stages.
• Dehydration (400�-650�C): This is also known as water
smoking stage. During dehydration,
• (1) the water which has been retained in the pores of the
clay after drying is driven off and the clay loses its plasticity,
(2) some of the carbonaceous matter is burnt, (3) a portion of
sulphur is distilled from pyrites. (4) hydrous minerals like ferric
hydroxide are dehydrated, and (5) the carbonate minerals are
more or less decarbonated. Too rapid heating causes cracking
or bursting of the bricks. On the other hand, if alkali is
contained in the clay or sulphur is present in large amount in
the coal, too slow heating of clay produces a scum on the
surface of the bricks.

25. • Oxidation Period (650�900�C): During the
oxidation period, (1) remainder of carbon is
eliminated and,
• (2) the ferrous iron is oxidized to the ferric form. The
removal of sulphur is completed only after the
carbon has been eliminated. Sulphur on account of
its affinity for oxygen, also holds back the oxidation
of iron. Consequently, in order to avoid black or
spongy cores, oxidation must proceed at such a rate
which will allow these changes to occur before the
heat becomes sufficient to close its pore. Sand is
often added to the raw clay to produce a more open
structure and thus provide escape of gases generated
in burning.

26. • Vitrification�To convert the mass into glass like
substance � the temperature ranges from 900�-1100�C for
low melting clay and 1000-1250�C for high melting clay.
Great care is required in cooling the bricks below the cherry
red heat in order to avoid checking and cracking. Generally,
clay products are vitrified to the point of viscosity. However,
paving bricks are burnt to the stage of complete vitrification
to achieve maximum hardness as well as toughness.

27. Burning of Bricks:
• Bricks are burned at high temperature to gain the strength,
durability, density and red colour appearance.
• All the water is removed at the temperature of 650 degrees
but they are burnt at an temperature of about 1100 degrees
because the fusing of sand and lime takes place at this
temperature and chemical bonding takes between these
materials after the temperature is cooled down resulting in
the hard and dense mass.
• Bricks are not burnt above this temperature because it will
result in the melting of the bricks and will result in a distorted
shape and a very hard mass when cooled which will not be
workable while brickwork. Bricks can be burnt using the
following methods:
• (a) Clamp Burning
• (b) Kiln Burning

28. Clamp Burning:
• Clamp is a temporary structure generally constructed over the
ground with a height of about 4 to 6 m. It is employed when
the demand of the bricks is lower scale and when it is not a
monsoon season.
• This is generally trapezoidal in plan whose shorter edge
among the parallel sides is below the ground and then the
surface raising constantly at about 15 degrees to reach the
other parallel edge over the ground.
• A vertical brick and mud wall is constructed at the lower edge
to support the stack of the brick. First layer of fuel is laid as
the bottom most layer with the coal, wood and other locally
available material like cow dung and husk.

29. • Another layer of about 4 to 5 rows of bricks is laid
and then again a fuel layer is laid over it. The
thickness of the fuel layer goes on with the height of
the clamp. After these alternate layers of the bricks
and fuel the top surface is covered with the mud so
as to preserve the heat.
• Fire is ignited at the bottom, once fire is started it is
kept under fire by itself for one or two months and
same time period is needed for the cooling of the
bricks.
• The production of bricks is 2-3 lacs and process takes
6 months.
• This process yields about 60 % first class bricks.

31. Disadvantages of Clamp burning:
• Bricks at the bottom are over-burnt while at the top
are under-burnt.
• Bricks loose their shape, and reason may be their
descending downward once the fuel layer is burnt.
• This method can not employed for the
manufacturing of large number of bricks and it is
costly in terms of fuel because large amount of heat
is wasted.
• It can not be employed in monsoon season.

32. Kiln Burning:
• Kiln is a large oven used for the burning of
bricks. Generally coal and other locally
available materials like wood, cow dung etc
can be used as fuel. They are of two types:
• (a) Intermittent Kilns.
• (b) Continuous Kilns.

33. • Intermittent Kilns- are also the periodic kind of kilns, because
in such kilns only one process can take place at one time.
Various major processes which takes place in the kilns are:
• Loading, unloading, Cooling, and Burning of bricks.
• Wastage of fuel is the disadvantage since walls have to be
heated again during reloading of bricks

35. Continuous Kilns:
• These kilns are called continuous because all the processes of
loading, unloading, cooling, Heating, pre-heating take place
simultaneously. They are used when the bricks are demanded
in larger scale and in short time. Bricks burning is completed
in one day, so it is a fast method of burning.
• There are two well known continuous kilns:
• Bull's Trench Kiln
• Hoffman’s kiln
• Bull's trench kiln consist of a rectangular, circular or oval plan
shape of 6 - 9 m wide, 2 - 2.5 m deep, and 100 - 150 m long
They are constructed below the ground level by excavating a
trench of the required width for the given capacity of brick
manufacturing.

36. • This Trench is divided generally in 12 chambers so that 2
numbers of cycles of brick burning can take place at the same
time for the larger production of the bricks. Or it may happen
that one cycle is carried out at one time in all the 12 chambers
by using a single process in the 2-3 chambers at the same
time.
• The structure is under-ground so the heat is conserved to a
large extent so it is more efficient. Once fire is started it
constantly travels from one chamber to the other chamber,
while other operations like loading, unloading, cooling,
burning and preheating taking place simultaneously.
• Such kilns are generally constructed to have a manufacturing
capacity of about 20,000 bricks per day. The drawback of this
kiln is that there is not a permanent roof, so it is not easy to
manufacture the bricks in the monsoon seasons.

37. • The green bricks to be fired are set in rows, two to three bricks wide, with
holes in between that allow feeding of coal and a sufficient flow of air
through the setting (Figure 2). A linking layer of bricks is made across the
width of the kiln and half way up, to stabilize the setting. On top of the
bricks, two layers of bricks, covered with ash or brick dust, seal the setting.
The trench contains 200 - 300,000 bricks at a time.
• Chimneys, 6 - 10 m high, made of sheet metal, are placed on top of the
brick setting. Small circular Bull's trench kilns use only one chimney,
whereas the larger elliptical kilns need two chimneys.
• The firing in a Bull's trench kiln is continuous, day and night. Green bricks
are loaded and finished bricks are drawn all the time. The fuel saving is
achieved by reusing part of the energy that is otherwise lost in periodic
kilns. As shown in Figure, the air for combustion is drawn through the
already fired but still hot bricks. The cooling bricks transfer their heat to
the combustion air, pre-heating it before it enters the firing zone. After
combustion, the hot exhaust gases pass through the yet unfired bricks on
their way to the chimneys. This pre-heats the bricks, so less fuel is needed
to bring the bricks to the maximum temperature. Once every 24 hours the
chimneys are moved forward 5 to 7 m

38. Bull trench kiln

39. Hoffman's Kiln:
• The main difference between the Bull's trench kiln and the
Hoffman kilns are:
• Hoffman's kiln is an over the ground structure while Bull's
Trench Kiln is an underground structure.
• Hoffman's kiln have a permanent roof while Bull's trench Kiln
do not have so it former can be used in 12 months a year to
manufacture bricks but later is stopped in the monsoon
season.
• Hoffman's kiln is generally circular in plan, and is constructed
over the ground. The whole structure is divided into the 12
chambers and all the processes takes place simultaneously
like in Bull's trench Kiln.

40. • With the kiln is in full operation two chambers will be open,
and the other ten sealed up at the door and by the
interconnecting steel dampers. If the chambers are numbered
from 1 to 12, then bricks are being unloaded from 2 and
loaded in 1. The damper is closed between 1 and 12, but
opens between all other chambers. Air is drawn through the
open door of 2 and through the bricks in 3, 4, 5, and 6, cooling
them down and at the same time being heated itself.
Chamber 7 is being fired, with fuel being fed at intervals
through the roof, which is immediately ignited by the hot air
from 6. The products of combustion pass on to 8, 9, 10, and
11 drying and pre-heating the bricks in these chambers The
chambers being loaded and unloaded move forward in
sequence, and this way heat is extracted from the cooling
bricks and also from the hot combustion gases.

42. Comparison between Clamp and kiln burning
Clamp burning Kiln burning
Temporary structure Permanent structure
Small quantity of bricks are required Large quantity of bricks
Initial cost less Initial cost more
Cost of fuel less : waste wood, cow dung More cost fuel: coal
Wastage of heat more and no
arrangement for utilising the heat of
gases
Proper arrangement
Once stacked and fired, no supervision
required
Skilled labourer and constant supervision
Time of burning: 2-6 months Time for burning: 24 hrs and cooling 10
days
30,000-1,000,00 at a time 25,000 bricks daily
% of 1st class brick 50-60 % % of 1st class brick 80-90 %

43. Classification of Bricks based on
Quality

44. Class I Bricks
• They are used where superior and
permanent work is desirable.
• Used when brick texture is supposed to be
exposed.

45. Class II Bricks
• These are commonly used in permanent
brick masonry work where the plastering is
followed.

46. Class III Bricks
• These are desirable for only least important
temporary works

47. Class IV Bricks
• These are overburnt bricks and have very little
compressive strength making them unfit for any masonry
work. They are used as aggregates for concrete roads, floor
and foundations

48. BRICKS SIZE
• Traditional bricks
Not standardized in size; dimensions vary; commonly adopted
23 cm x 11.4 cm x 7.6 cm
• Modular bricks
BIS standards
Nominal size : 20 x 10 x 10 (cm)
Actual size : 19 x 9 x 9 (cm)

49. Absorption: A good should not absorb not more than 20 percent of
weight of dry brick
Compressive strength: crushing or compressive strength of brick
is found out by placing it in compression testing machine. It is
pressed till it breaks. Minimum crushing strength of brick is
35kg/cm^2 and for superior bricks, it may vary from 70 to 140
kg/cm^2.
•Hardness: No impression is left on the surface the brick is treated
to be sufficiently hard
•Presence of soluble salts: The bricks should not show any grey or
white deposits after immersed in water for 24 hours
•Shape and size: It should be standard size and shape with sharp
edges
•Soundness: The brick should give clear ringing sound struck each
other
•Structure: The structure should be homogeneous, compact and
free from any defects
TESTING OF BRICKS

50. Tests on Bricks

51. Compressive Strength Test
Couple of bricks are taken at random and
soaked in water for 24 hours. They are
then taken out and allowed to drain the
water absorbed. The bricks are then
applied with a compressive load at a rate
of 140 kg/sq cm per minute and the
ultimate strength is obtained. The average
value indicated the compressive strength
of the batch of given bricks.

52. Water Absorption Test
Couple of bricks are taken at random and
dried until a constant weight is obtained.
This usually takes 48 hours. They are then
cooled to room temperature and soaked
into clean water for 24 hours. They are
then taken out and weighed again to
obtain % increase in weight.

53. Efflorescence Test
The presence of soluble salt in bricks
cause efflorescence on surface. Couple of
samples are taken and immersed in
distilled water. They are then taken out
and the water is allowed to evaporate.
This process is repeated thrice or four
times to test the appearance of salt
patched on the surface.

54. Dimension Tolerance Test
The process of making of bricks involves
high temperatures during which the
dimension of moulded bricks could
change. Couple of bricks are selected at
random and their size is analysed with the
accuracy of 1mm.

55. Hardness Test
Hardness refers to the material’s ability to
resist surface abrasion. Couple of bricks
are selected at random and are tested for
hardness by scratching with fingernail.

56. Soundness Test
When two bricks are struck together, it
must produce a metallic sound which is a
characteristic of good quality bricks.
Couple of bricks are selected at random
and are tested with a reference brick for
soundness test.

57. Types of bricks
• High Alumina Bricks
High alumina bricks from 50% upto 90% Alumina are made
with various selected superior grade aggregates to meet the
various service conditions of various types of furnaces like
blast furnace, cement and sponge iron Rotary Kiln, calciner ,
etc., The 90% alumina dense bricks are manufactured from
tabular alumina purer micro fine alumina and other special
type raw material and fired in ultra high temperature kiln at
1650-1700 deg C. Due to the intent micro structural features
of the raw materials used for these bricks, they have excellent
resistance to wear and thermal shock.

59. • Light Weight Hollow Blocks
This blocks are used in construction of houses
in earthquake prone areas. These bricks are
made of fly ash, cement, lime, gypsum, stone
dust etc. Available in different sizes. Hollow
concrete blocks is used as substitute for
conventional bricks or stones used in
construction of buildings

61. Sand Lime Bricks
• Sand lime bricks are made by mixing sand, fly ash and lime
followed by a chemical process during wet mixing. The mix is
then moulded under pressure forming the brick. These bricks
can offer advantages over clay bricks such as:
• Their colour appearance is gray instead of the regular reddish
colour.
• Their shape is uniform and presents a smoother finish that
doesn’t require plastering.
• These bricks offer excellent strength as a load-bearing
member.
• These bricks are used for several purposes in construction
industries such as ornamental works in buildings, masonry
works etc.
• Sand lime bricks are popularly used in European countries,
Australia and African countries. In India, these bricks are
widely used in Kerala state and its usage is regularly growing.

62. Sand Lime brick

63. Concrete Bricks
• Concrete bricks are made from solid concrete
and are very common among homebuilders.
Concrete bricks are usually placed in facades,
fences, and provide an excellent aesthetic
presence. These bricks can be manufactured
to provide different colors as pigmented
during its production.

65. Fly Ash Clay Bricks
• Fly ash clay bricks are manufactured with clay
and fly ash, at about 1,000 degrees C. Some
studies have shown that these bricks tend to
fail poor produce pop-outs, when bricks come
into contact with moisture and water, causing
the bricks to expand.

67. Fireclay
• Fire clay/ refractory clay vitrify at a high temperature
• Has usually whiter-lighter colour. Whitish to yellowish,
pinkish, light brownish. It’s also cheap as mud. Refractory or
pottery suppliers sell it. Even if it comes in dry powdered form
in bags, fire clay is still very heavy.
• Silica 55%, Alumina 20-35 %, Iron oxide 2-5 %, 1 % of lime,
magnesia and alkalis.
• Capable of resisting high temperature upto 1700 degrees C

68. Fireclay or Refractory bricks
• Manufactured in Hoffman’s kiln
• Colour is whitish yellow or light brown
• Water absorption of fire clay bricks varies from 4-10 %
• Used for lining blast furnaces, ovens, kilns, boilers and
chimneys

69. • Acid refractory bricks: 95-97 % silica and 1-2%
lime
• Silica bricks are hard
• Tendency to spall during rapid temperature
change, cant be used for lining of furnaces

70. • Structural uses: such as foundations walls and floors.
• Decorative/ornamental uses: May be cast to from moldings
and other decorative features may be carved also may be used
in a variety of colors, textures, bonds and joints.
• May be concealed by other finish materials such
as plaster or paint, or may be exposed both on
the interior and exterior.
• Bricks are also used in the metallurgy and
glass industries for lining furnaces.
• They have various uses, especially refractory bricks such
as silica, magnesia, chromomagnesite refractory
bricks. This type of brick must have good thermal shock
resistance, under load, high melting point, and satisfactory
porosity.
• Bricks are used for building and pavement.
Uses

71. Advantages
• The use of materials such as brick and stone can increase the
thermal mass of building, giving increased comfort in the heat
of summer and cold of winter and can be ideal for passive
solar applications.
• Brick typically will not require painting and so can provide a
structure with reduced life cycle costs. Concrete block of the
non decorative variety generally is painted if exposed.
• The appearance especially when well crafted, can impart an
impression of solidity and permanence.
• Brick is very heat resistant material and thus will provide good
fire protection.
• Being much more resistant
to cold and moist weather conditions, brick enabled the
construction of permanent buildings in regions where the
harsher climate precluded the use of mud bricks.

73. Bonds in Brickwork
• Bonds is the method of arranging the bricks in courses and
vertical joints of successive courses are not in same line.
Rules for bonding
• Bricks should be of uniform size
• Amount of lap should be minimum ¼ brick along the length of the wall
and ½ brick along thickness of wall.
• Use of brick bats should be discouraged except in special locations
• Vertical joints in alternate courses should be along same perpend.

74. TYPES OF BONDS
• Stretcher bond
• Header bond
• English bond
• Flemish bond
• Zig Zag bond

75. Stretcher bond
• Bricks are laid as stretchers on the faces of wall, length of
bricks is along the face
• Use for walls which have thickness of half brick i.e. 9 cm
• Used as Partition walls, chimney stacks
• This bond is not possible if thickness is more

76. Header bond
• Bricks are laid down as headers, width is along the direction
of wall.
• Used only when thickness of wall is equal to one brick
• This bond is not suitable for transmitting pressure in the
direction of wall, hence not used for load bearing walls.
• Used for curved brick work

77. • Most commonly used bond for all wall thickness
• Strongest bond; Alternate course of headers and stretchers;
Vertical joints of header courses come over each other; same
with stretcher.
• In order to break the vertical joints in the successive courses,
it is essential to place queen closer after the first quoin
header in each heading course.
• In a stretcher course, the lap must be minimum ¼ of their
length.
English bond

79. Flemish Bond
• Each course is comprised of alternate headers and stretchers.
Every alternate course starts with a header at the corner
(quoin header).
• Queen closer are placed next to quoin header in alternate
course to develop the face lap.
• Two types: Double flemish bond; Single flemish bond
• In double; each course presents the same appearance both in
front and back face; presents better appearance than English
bond
• In walls having thickness equal to odd multiple of half bricks,
half bats and three quarter bats are used.
• In single flemish; uses English bond backing and double
flemish bond facing
• Can be used for walls having thickness at least equal to 1 ½

81. Comparison of English and Flemish bond
• English bond is stronger than Flemish bond for
walls thicker than 1 ½ brick
• Flemish bond gives more pleasing appearance
and requires greater skill than English bond
• Broken bricks in the form of bats can be used
in Flemish bond

82. Used for making ornamental panels in the brick flooring

83. Comparison of Brick and Stone masonry
• Brick masonry can be constructed with less
skilled masons in comparison to stone work.
Hence brickwork is cheaper.
• No special lifting arrangement is required for
bricks
• Brick masonry can be used in any type of
mortar; mud mortar can be used in low rise
houses
• Better fire resistant than stones

84. • Stone masonry is stronger than brick masonry
of same wall thickness
• Life of stone masonry longer than bricks
• Stone masonry doesn’t require external
plaster.
• Stone masonry more water tight than bricks.

85. Defects in Brick masonry
• Sulphate attack: sulphate salts
present in brick react with
hydraulic lime in case of lime
mortar and with alumina
present in cement mortar,
volume of mortar increases;
chipping and spalling of bricks
• Crystallization of salts: If bricks
containing soluble salts get
dissolved with water, appear in
the form of fine white crystals
on the surface; Efflorescence
• Corrosion of iron or steel
fixture
• Drying shrinkage leading to
cracks

86. REFERENCES
• Building construction materials techniques, P.
Purushottam Raj
• Building Materials, S.K. Duggal
• Building Materials, B C Punmia
• www.civilconstructor.org