This document describes the properties of bricks, including their physical, mechanical, and thermal characteristics. It discusses the shape, size, color, density, compressive strength, insulation properties, durability, and frost resistance of standard bricks. It also outlines various tests conducted on bricks, such as those measuring compressive strength and water absorption. Additionally, it defines the qualities of good bricks and provides a classification system for bricks based on their characteristics and intended uses. Special types of bricks are also outlined, including those with modified shapes, perforations, and alternative compositions like sand lime bricks and refractory fire bricks.

1. Bricks

2. Properties Of Bricks
• Physical properties
• Shape
• Size
• Colour
• Density
• Mechanical properties
• Compressive strength
• Flexure strength
• Thermal characteristics: Insulation property
• Durability property
• Absorption value
• Frost resistance
• Efflorescence

3. Properties Of Bricks

4. Properties Of Bricks
• Physical Properties
Shape:
• Standard shape - truly rectangular.
• Sharp and true right angled corners.
• Surface of bricks - regular and even.
• Special purpose bricks may be either cut or manufacture in various
other shapes.
Size:
• varies from country to country even place to place.
• Standard size: 19 cm * 9 cm * 9 cm
• Found very convenient in handling the bricks during construction and
making quantity estimation.
• Five hundred such bricks will be required for completing one cubic
meter of brick masonry.
• Pakistan and Bangladesh: 22 cm * 10.5 cm * 7 cm
• UK : 20 cm * 9.5 cm * 5.5 cm
• U.S.A: 20 cm * 10 cm * 10 cm or 30 cm * 10 cm * 10 cm

5. Properties Of Bricks

6. Properties Of Bricks
Colour:
• Uniform and bright. Most common colour falls under the
class red.
• Varies from dark red to light red colour.
• Very dark red colour indicates over burning and yellow
colour indicates under burning.
Density:
• Depends upon the type of clay used and method of
moulding.
• Varies from 1600 kg/m3 to 1900 kg/m3
• A single brick (19 cm * 9 cm * 9 cm) weight: 3.2 to 3.5 kg.

7. Properties Of Bricks

8. Properties Of Bricks
• Mechanical Properties
• Compressive strength:
• Most important property of bricks because they are to be used in load
bearing walls.
• It depends on the composition of clay and degree of burning.
• Varies from 35 kg/cm2 to 200 kg/cm2.
• Flexure strength:
• Bricks are often used in situation where bending loads are likely to
develop in building, so strength is required to take transverse loads.
• It should not be less than 10 kg/cm2 for common building.
• It should be more than 20 kg/cm2 for best grade bricks.
• Good building bricks – shearing strength 50-70 kg/cm2

9. Properties Of Bricks

10. Properties Of Bricks
• Insulation Property
• Ideal Brick Should Provide Adequate Insulation
Against Heat, Cold And Noise.
• The Heat And Sound Conductivity Of Bricks Varies
Greatly With Their Density And Porosity.
• Very Dense And Heavy Bricks Conduct Heat And
Sound At A Greater Rate. So, They Have Poor
Thermal And Sound Insulation Qualities.
• Bricks Should Be Design In Such A Way That They
Are Light Strong And Give Adequate Insulation.

11. Properties Of Bricks

12. Properties Of Bricks
• Durability Property: length of the time for which
they remain unaltered and strong when used in
construction. It depends on following factors:
• Absorption value: related to porosity of the brick.
• True porosity: it is defined as the ratio of volume of the
pores to gross volume of the sample of the substance.
• Apparent porosity: it is the quantity of water absorbed by
the brick sample.
• For ordinary bricks – not greater than 25%.
• Frost resistance: water on freezing expands by about 10%
in volume and exerts a pressure of the order of 140 kg/cm2

13. Properties Of Bricks

14. Properties Of Bricks
• Cold climate – decay.
• Efflorescence: it is disfiguring and deteriorating process of
brick in hot and humid climates.
• Brick surface gets covered with white or grey coloured
patches of salts (presents in ordinary clay).
• When rain water penetrates, salts get dissolved.
• When evaporation starts, salts move out along with the
water.
• Sulphates of calcium, magnesium, sodium and
potassium.

15. Properties Of Bricks

16. Qualities of Good Brick
• It should be uniform shape and should be of
standard size (ISI: 190 mm x 90 mm x 90 mm,
Depth of frog – 10 to 20 mm, Length of frog – 100
mm, Width of frog – 40 mm, Size including mortar
joint 200 mm x 100 mm x 100 mm, weight - 30 N).
• It should be properly burnt.
• It should give clear ringing sound when struck each
other.
• Bricks when broken should show a bright
homogeneous and compact structure free from
voids.

17. Qualities of Good Brick

18. Qualities of Good Brick
• It should not absorb water more than 20 percent of its dry
weight for first class bricks. Absorption should not exceed
25% in any case.
• It should have good compressive strength, not less than 35
kg/cm2 .
• It should be sufficiently hard enough so that it should not
scratched by finger nail.
• Bricks should be low thermal conductivity and they should
be sound proof.
• It should have uniform colour (copper coloured) and
structure (free from cracks, sharp & square edges) through
out its body.

19. Qualities of Good Brick
• It should have adequate resistance to fire and can
resist temperature upto 1200⁰C.
• It should not contain much alkaline salts, which
may cause efflorescence on surface and decay the
bricks.
• It should be able to resist the weathering effects like
temperature variations, rain frost action etc.

20. Qualities of Good Brick

21. Classification Of Bricks (ISS 1077-1971)
Class Characteristics Use
FIRST • Well burnt having even surface and perfectly
rectangular shape
• Clear ringing sound produced, when struck
each other.
• Compressive strength, not less than 140 kg/cm2
and its absorption after 24 hours immersion shall
not exceed 20%
• Uniform appearance, texture and structure.
• Specific gravity 1.8
• Should not break when dropped from 1 to 2 m
height
• Excellent for all types of
construction in the exterior
walls when the plastering is
not required.
• Suitable for flooring.
• Shaped bricks are used in
carvings, arches and copings
SECOND • Well burnt, even slightly over burning is
accepted.
• Clear metallic-ringing sound is also must.
• Compressive strength, not less than 70 kg/cm2
and absorption value between 20 to 22 %.
• Rectangular but slightly irregularity is permitted.
• Surface may be slightly uneven.
• Fine, compact and uniform texture
• For exterior works when the
plastering is to be done.
• For internal walls
• May not be used for
flooring.

22. Classification Of Bricks (ISS 1077-1971)
Class Characteristics Use
THIRD • Poorly and uneven burnt, it may be over
burnt or under burnt
• Dull sound produced, when struck each
other.
• Compressive strength, lies between 35 - 70
kg/cm2 and its absorption after 24 hrs,
absorption between 22 – 25 %.
• Appearance, shape and size are also non-
uniform and irregular.
• Soft, associated with flaws & cracks
• Used mostly in ordinary
type of construction and in
dry situations.
• For temporary building
FOURTH
class or
JHAMA
• Irregular in shape and dark in colour due
to over burning.
• Low in porosity and absorption.
• Unfit for use in building
construction because of
irregular size.
• Used in broken form.
• Used as aggregate for
concrete in foundation,
floors, roads, etc
Heavy Duty bricks: exceptionally dense, perfectly burnt and very strong bricks
compressive strength- 440 kg/cm2.

23. Standard Tests For Bricks (ISS – 1077-1970)

24. Compressive Strength of Bricks

25. Standard Tests For Bricks (ISS – 1077-1970)

26. Water Absorption of Bricks

27. Standard Tests For Bricks (ISS – 1077-1970)
Efflorescence Test:
• Take 5 bricks at random.
• Place each brick in separate shallow flat bottom
dish containing distilled water.
• Depth of immersion should not be less than 2.5
cm.
• Keep these in warm room (18 to 300 C) with
adequate ventilation.
• Add fresh quantity of water when the bricks
dries.
• At the end of 2nd drying, observed for
appearance.

28. Efflorescence Test

29. Standard Tests For Bricks (ISS – 1077-1970)
• Serious: salt deposition is all around and quite
heavy. Powdering of salt is prominent.
• Heavy: salt deposits covers more than 50% area.
Tendency to powder is absent.
• Moderate: salt deposits covers more than 50%
area. Forms thin layers without showing any
tendency to peal off in flacks or become powder.
• Slight: salt covers surface area of less than 10%
area. Forms only a very thin sticky layer.
• Nil: no deposits of any salt even after repeated
wetting.

30. Special Types Of Bricks

31. Special Type Of Bricks
• Ordinary bricks are typically rectangular
in shape, solid in structure and made from
suitable type of brick-clays.
• Different types of groups for special type of
brick:
• Types where shape is modified
• Types with perforation in the body
• Types where a different material is used
to make the bricks.

32. Types Based On Modification In Shape
• Different situations where a perfect rectangular shape is not
suitable. Specially moulded bricks avoid the cumbersome process
of cutting & rounding rectangular bricks to the desired shape.
• E.g. plinth, the corners of walls and at the copings.
• King closer: the brick is so cut that it has length and width on one
side only. (corner cut)
• Queen closer: the brick cut is lengthwise so that brick has only
one half of the length.
• Squint brick: cut brick, the portion of cut forms angles other than
right angle.
• Splay bricks: These have level or portion taken off, width-wise,
length-wise or in both directions, which includes:
• Plinth header:
• Plinth stretcher:
• Plinth return:
• Coping bricks, bullnose, cow nose, miscellaneous shape.

33. Types Based On Modification In
Shape

34. Special Type Of Bricks
Queen CloserKing Closer
Squint Brick
Splay Bricks – Plinth Header
Splay bricks - Plinth stretcher
Splay Bricks - Plinth Return

35. Types Based On Perforations
• There are mainly three types of bricks:
• Perforated bricks
• Hollow bricks
• Channelled bricks
• Perforated bricks:
• Modern class of building bricks.
• Cylindrical, rounded or rectangular holes are made in the
bricks after the moulding stage. These holes are called
perforations.
• Properly spaced from the side of the bricks, min 15 mm
• The volume of perforations may be as much as 20 to
50% of total volume of the brick.
• Bricks may be larger in size which can increase work
output.

36. Perforated Bricks
• Advantages of perforated bricks:
• Light in weight
• Less quantity of clay is required for
manufacture.
• Less time required for drying and burning.
• Better resistance against rain penetration and better
insulation against heat, which is suited for tropical
countries.
• Efflorescence is least.
• Specially suitable for construction of brick
panel in multi storied structure.
• Widely used in Germany, France and America.

37. Perforated Bricks

38. Hollow Bricks
(Cavity Bricks Or Cellular Bricks)
• A few well defined sets of cavities with specified
dimensions made in the body of brick.
• Net weight = one third to one half of the solid brick.
• The thickness of the brick wall near to cavity should not
be less than 2 cm.
• The cavity extends throughout the body of the brick.
• Made from the special homogeneous clay.
• Advantages:
• More convenience and output may be three to four times
compared to ordinary bricks.
• Offer better insulation against heat, sound and dampness
• Ideal and economical for non-load bearing walls (e.g.
Partition walls)

39. Channel Or Gutter Bricks
• Continuous central semi circular cavity or
depression running through their length.
• Use: laying of drains
Hollow Bricks Channel Brick

40. Types Based On Composition
• There are mainly two major sub-classes of
bricks:
• Sand lime bricks (the common building bricks)
• Refractory bricks: has a specific use in
industrial processes.
• Sand lime bricks: bricks made from sand and lime as
the raw material instead of clay. The clay content may
be negligible.
• Method of manufacture and composition are different
from ordinary bricks.
• Shape and size is similar.

41. Sand Lime Bricks
• Manufacture: raw materials are:
• Sand: free from harmful impurities like mica, chlorine, iron
oxides black minerals and organic matter. (Around 90%)
• Lime: hydrated (slaked) lime. (8-12%)
• Has high-calcium content and should be free from
magnesium.
• Clay - upto 4%
• Salt Free Water (not sea water).
• For different colours, pigments are added in small
percentages.
• Iron oxides – for red and brown colour
• Chromium oxide – for green colour
• Ochre – for yellow colour
• Carbon black – for grey and black colour

42. Sand Lime Bricks

43. Sand Lime Bricks
• Moulding: after mixing powdered raw materials in the
desired proportion, add 2-3 % clean water to obtain
damp moisture.
• Moulded using Rotary press under pressure ranging from
300 – 600 kg/cm2 which results into highly compressed
and dense sand lime bricks, almost dry at this stage.
• Auto-claving: A steel cylinder with closed end where
heating is done by steam under pressure – Auto-clave.
• Bricks are treated for 6-12 hrs under steam pressure
between 8-16 kg/cm2.
• Sand and lime react chemically and form chemical
compound: calcium silicate – chemical composition of
brick.
• The bricks taken out from the auto-clave are ready for use.

44. Sand Lime Bricks

45. Sand Lime Bricks
• Properties:
• Very smooth and uniform finish and a pleasing
appearance.
• Dense, strong and hard.
• Least porous and hence free from efflorescence.
• Uniform in shape, size and finish and no plastering
requires.
• When requires, quantity of plaster is quite less.
• Water repelling.
• Material required are quite common in occurrence, can be
used as alternative of clay bricks.
• Disadvantages:
• Manufactured only by using mechanised method.
• Unsuitable for foundation and paving because bricks
can be damaged in presence of water and poor resistance
to abrasion.

46. Refractory Bricks Or Fire Bricks
• Separate group of bricks, which is capable to withstanding very
high temperature without undergoing any deformation in size or
shape and without reacting with the material of a particular
composition at these temperature.
• Use: making of inner walls of furnaces for manufacture of metals and
for similar high temperature applications.
• Classification: based on their reactivity towards melts at high
temperature.
• Acidic bricks: resistant to the metals of acidic composition but react
with the basic composition.
– E.g: fire clay bricks, silica bricks
• Basic bricks: resistant to the metals of basic composition.
– Not suitable in those furnaces where acidic melts are being heated.
– E.g. magnesia bricks, bauxite bricks.
• Neutral bricks: non reactive to both acidic and basic melts.
– Find application in heating either type of melts.
– E.g. chromite bricks, chrome-magnesite bricks.

47. Refractory Bricks Or Fire Bricks

48. Refractory Bricks Or Fire Bricks
• Manufacture: same as building bricks.
• The raw materials are first crushed to the required
size and mixed thoroughly in the presence of required
quantity of water.
• From this homogeneous mix, bricks are moulded.
• Dried and then burnt at very high temperature,
between 1600-20000C.
• Allowed to cool very gradually.

49. Refractory Bricks Or Fire Bricks

50. Different Important Refractory Bricks Or Fire Bricks
Fire clay bricks: Refractory materials of acidic group.
• Raw material: it can withstand very high temperature without fusing or
softening.
• Available under the coal layer in nature.
• Silica (65-75 %) and alumina (25-35 %)
• Free from impurities like oxides of calcium, magnesium and iron.
• Maximum limit for impurities = 5%
• Manufacture – similar to common building bricks.
• Temp very high – 16000 – 19000 C
• Types of fire clay bricks
• High duty fire clays – 1482-16480 C
• Medium duty fire clays – 1315-14810 C
• low duty fire clays – 870 -13140 C
• Properties: high resistance to spalling (breaking under heat).
high bearing capacity
low coefficient of thermal expansion
• Use: lining material in steel making furnaces, glass making furnaces.

51. Fire Clay Bricks

52. Different Important Refractory Bricks
Or Fire Bricks
Silica Fire Bricks: acidic bricks made up mostly of silica (more
than 95%) and Calcium oxide (binding agent).
Raw material - pure quartz or sandstone of high silica content.
Burnt to around 15000 C, compressive strength – 15 MPa
Properties: Low porosity and free from air pockets
Good thermal expansion and conductivity
Remarkable load bearing capacity especially at
high temperature
Ability to withstand thermal shock
Use: lining material, roofs of acid and basic open hearth
furnaces, electric furnaces, refining furnaces

53. Silica Fire Bricks

54. Different Important Refractory Bricks
Or Fire Bricks
Magnesium Fire Bricks: Basic Refractories
Raw material – magnesia = 85% (min.), calcium oxide =
25% (max.), silica = 5.5% (max.)
Source – rock dolomite
Properties: Thermal conductivity greater than that for fire
clay and silica fire bricks.
Highly resistant to the action of basic slags and
iron oxides
Starts losing strength at temperature above 15000
C
Use: Hearths of basic open-hearth and copper
reverberatory furnaces, electric arc and induction
furnaces

55. Magnesium Fire Bricks

56. Different Important Refractory Bricks Or Fire
Bricks
Bauxite Fire Bricks: very important class of basic refractories
Source – rock bauxite, which may be mixed with some clay.
Properties: Bricks are highly refractory, not commonly used because
of high shrinkage at high temperature
Chromite Fire Bricks: neutral class of refractories.
Raw material – chromite (double oxide of chromium and iron in its
composition)
Some alumina and silica are also added to make a typical neutral
material.
Capable to resist both the acidic and basic environment in a furnace.
Properties: Low porosity
High resistance to both acid and basic slags
High thermal conductivity
Low resistance to spalling
Use: steel making furnaces.

57. Bauxite Fire Bricks

58. References
• Building Construction : Dr B.C. Punmia
• Civil Engineering Material : Prof. Singh
• Internet Web Sites

59. Thanks…