Bricks

INTRODUCTION TO HISTORICALINTRODUCTION TO HISTORICAL
DEVELOPMENTS IN MASONRYDEVELOPMENTS IN MASONRY
• It is the simplest of all the building techniques - Mason stacksIt is the simplest of all the building techniques - Mason stacks
pieces of material (bricks, stones, concrete blocks, etc.) over thepieces of material (bricks, stones, concrete blocks, etc.) over the
top of one another to make walls, with mud or mortar as bindingtop of one another to make walls, with mud or mortar as binding
material in between themmaterial in between them
HistoryHistory
• Began as low walls of stones or caked mudBegan as low walls of stones or caked mud
• Sun-dried bricks - With the availability of fire became burnt bricksSun-dried bricks - With the availability of fire became burnt bricks
• Invention of kilns made mass production of bricks easyInvention of kilns made mass production of bricks easy
• Limestone turned into lime mortar replaced mud as mortarLimestone turned into lime mortar replaced mud as mortar
• In Mesopotamia, palaces and temples were built of stone and sun-In Mesopotamia, palaces and temples were built of stone and sun-
dried bricks in 4000 B.C.dried bricks in 4000 B.C.
• The Egyptians erected their temples and pyramids of stones byThe Egyptians erected their temples and pyramids of stones by
3000 B.C.3000 B.C.
• By 300 B.C., Greeks perfected their temples of limestone andBy 300 B.C., Greeks perfected their temples of limestone and
marblemarble
• Romans made the first large-scale use of masonry arches and roofRomans made the first large-scale use of masonry arches and roof
vaults in their basilica, baths and aqueductsvaults in their basilica, baths and aqueducts

DEVELOPMENTS IN MASONRYDEVELOPMENTS IN MASONRY (Cont’d)(Cont’d)
• Medieval and Islamic civilizations perfected masonry vaultingMedieval and Islamic civilizations perfected masonry vaulting
to a high degree of development - Islamic craftsmen builtto a high degree of development - Islamic craftsmen built
palaces, markets, and mosques of bricks and often facedpalaces, markets, and mosques of bricks and often faced
them with brightly glazed tilesthem with brightly glazed tiles
• Europeans built fortresses and cathedrals using pointed vaultsEuropeans built fortresses and cathedrals using pointed vaults
and flying buttressesand flying buttresses
• In America and Asia other cultures were building with stonesIn America and Asia other cultures were building with stones
• During industrial revolution, machines were developed toDuring industrial revolution, machines were developed to
quarry and cut stones, mould bricks, and speed thequarry and cut stones, mould bricks, and speed the
transportation of these materials to site of buildingtransportation of these materials to site of building
• Portland cement came into wide use and this enabled thePortland cement came into wide use and this enabled the
construction of masonry building of greater strength andconstruction of masonry building of greater strength and
durabilitydurability

• Late in 19th century tall buildings were built, of steel andLate in 19th century tall buildings were built, of steel and
reinforced concrete (pored into simple forms), economicallyreinforced concrete (pored into simple forms), economically
• Development of hollow concrete forms in 19th centuryDevelopment of hollow concrete forms in 19th century
averted the extinction of masonry as a building material -averted the extinction of masonry as a building material -
Cavity wall, developed by the British during the earlier part ofCavity wall, developed by the British during the earlier part of
the 19th century also contributed to the survival of masonrythe 19th century also contributed to the survival of masonry
as a building materialas a building material
• This facilitated the introduction of thermal insulationThis facilitated the introduction of thermal insulation
• High strength mortars, high-strength masonry units, andHigh strength mortars, high-strength masonry units, and
complex shapes of masonry units extended the use ofcomplex shapes of masonry units extended the use of
masonry for buildingsmasonry for buildings
DEVELOPMENTS IN MASONRYDEVELOPMENTS IN MASONRY (Cont’d)(Cont’d)

Masonry - Primary Uses TodayMasonry - Primary Uses Today
 Concrete Masonry Units (CMU)Concrete Masonry Units (CMU)
Foundation WallsFoundation Walls
Structural Support Walls (low rise)Structural Support Walls (low rise)
Backup Walls for Exterior FacingBackup Walls for Exterior Facing
 Brick & StoneBrick & Stone
Facing Materials - VeneersFacing Materials - Veneers
Decorative WallsDecorative Walls

CMU Structural Walls on a Low Rise Building

Reinforcing Structural CMU Walls

• Bricks will categorized with different used:
– load bearing wall
– Non-Load bearing wall
– Insulation wall
– Covering wall.
• Selection of bricks based on their using.
• Brick shape : 4 side geometric with length 2 x from
width. The thickness is 2/3 of width
• Standard size of bricks is 215 x 102.5 x 65 mm
• It’s can be made from clay, sand & lime, cement
mortar

Brick will not burn, buckle or melt.
Brick will not rot and allow Termites to invade.
Brick will not rust and corrode.
Brick will not dent.
Brick will not fade from the Sun's UV (ultra-violet) Rays.
Brick will not be damaged by high winds, rain or hail.
Brick will not require constant maintenance.
Brick will not devalue.
Brick will not limit your personal expression.
Brick will not limit your design options.

Clay Bricks
• Manufactured from clay. The basic
compositions of clay brick are:
i. Silica (Si O2
) – 60%
ii. Alumina (Al2
O2
) – 20%
iii. Remaining ingredients – 20%
• Remaining ingredients such as:
i. Calcium oxide
ii. Iron oxide – give pleasing red colour
iii. Manganese
iv. Magnesium oxide

Functions of Ingredients
• Silica – Free silica (sand), if added to clay in
suitable proportion makes a brick hard and
prevents it from warping and shrinking on drying.
• Alumina – Alumina is main constituent of every
clay. On the addition of water clay becomes
plastic and can be moulded into shape.
• Lime – It helps to lower the fusion temperature,
i.e. it helps silica to fuse at lower temperature and
thus helps to bind the particle together. It also
prevents shrinkage of raw bricks

Harmful ingredients
• Alkalise – The alkalise lower the fusion
temperature and melts the brick, changes it shape
or get twisted. Also these salts have hygroscopic
action.
• Iron pyrites – during burning, iron pyrites due to
high temperature oxidise, decompose and
disintegrate brick into pieces.
• Organic matter – Although the presence of
organic matter in brick helps it burning, this
causes porosity in the bricks. The presence of
organic matter such as roots, dry leaves, in brick
should be avoided.

Characteristics of good
bricks
1. Appearance and colour – A good brick should have a
uniform rectangular shape with even surfaces and sharp
corners. It should be free from cracks. It should have a
uniform brick-red colour.
2. Hardness and soundness – Good bricks should be hard
and should not be scratched by fingernail. Also, should give a
metallic sound when two brick are struck to each other.
3. Durability – A good brick should be able to withstand
weathering actions of Sun, rain wind etc.
4. Fire resistance – A good brick should be able to withstand a
temperature up to 1500˚ F or 816˚ C.
5. Strength – A good brick is strong enough to not to break,
when dropped on another brick from a height of about 1.25
Meters.

• Engineering bricks :-
6. Water absorption – A good brick should not
absorb more than 20% of water by weight, when
placed in water for 24 hours.
7. Efflorescence – It should not contain much
alkaline salts which causes efflorescence on the
surface and decays the brick.
Min. Compressive
Strength
Max. water
absorption
Class A 70 N/mm2
4.5%
Class B 50 N/mm2
7.0%

Types of clay bricks
• Common type or common bricks
– These are ordinary bricks, which are not designed
to provide good finishes appearance or high
strength
• Facing bricks
– These are designed to give attractive appearance;
hence they are free from imperfections such as
cracks
• Engineering bricks
– These are designed primarily for strength and
durability. They are usually of high density and well
fired.

• Facing bricks are used primarily in the
construction of external walls in domestic
and commercial applications.
• They are chosen for their aesthetic appeal
and technical characteristics, including
their speed of use in construction.
• They must also meet minimum standards
for weather resistance.
• Facing bricks are made using either soft
mud or extruded techniques.
• Soft mud bricks are generally more
expensive to produce than extruded
bricks.
• Soft mud bricks are made by throwing clay
into a mould.
• This throwing process is generally
automated, but some soft mud bricks are
hand-made
• Engineering bricks are designed for use
where the strength of the brick or the
need for a brick to have a low level of
water absorption is paramount (eg in the
construction of retaining walls or for
ground works.
• Engineering bricks are usually extruded
bricks. The majority of engineering bricks
sold are smooth red Class B bricks, which
are also among the cheapest bricks sold.
Class A engineering bricks have lower
water absorption than Class B engineering
bricks and are more expensive to buy.
• They are often blue-grey in appearance,
and are generally used in facing
applications on account of their distinctive
appearance.
• In most, but not all, facing applications,
Class B engineering bricks are considered
to be less attractive than facing bricks,
and their colour may be less uniform.
Different between facing bricks & engineering bricks

Manufacture - 4 stages
◦ Material preparation
◦ Moulding
◦ drying
◦ Firing
Material Preparation:
material (clay) washed and
grinding (fineness)
Sample of grinding machine
for clay
Sample of crushing machine

Materials / Clay preparation
• Clay is prepared by crushing and/or
grinding and mixing with small quantities
of sand, ash and lime until it is of a
uniform consistency.
• Water may be added to increase plasticity
(a process known as ‘tempering’). In some
cases chemicals such as barium
carbonate is added to reduce the problem
of efflorescence, crystallisation damage or
chemical attack of the mortar.

Materials preparation
Weathering
• The soil is left in heaps and exposed to weather for
at least one month in cases where such weathering is
considered necessary for soil.
• The soil is turned at least twice and it is ensured that
the entire soil is wet throughout the period of
weathering.
• The purpose of weathering is to disintegrate big
boulders of clay under the action of atmospheric
agencies to make it a uniform mass and also to
eliminate the impurities which get oxidized.

Materials preparation (Cont’d)
Tempering
• After weathering, the required quantity of water
should be mixed with the soil to obtain the right
consistency for moulding. Addition of sand and other
materials, if necessary, may be made at this stage to
modify the composition of the soil.
• The quantity of water to be added, may range from
¼ to 1/3 of the weight of soil, sandy soils requiring
less water and clayey soils more water. But the
nature and degree of wetness of the soil at this stage
should also be duly considered.

• There are 4 methods of moulding;
– Semi-dry process
– Stiff plastic process
– Wire-cut process
– Soft mud process

• Used in manufacture of bricks having a moisture
content of around 10% in the clay
• The ground and the screened material has a dry
granular consistency which is still evident in the
fractured surfaces of the fired brick

• Applicable to clays having a moisture content of
about 15%
• Should possess stiff plasticity
• Clay is extruded and then compacted into a mould
under higher pressure
• Many engineering blocks are made by this process

• Clay is tempered to 20% moisture content
• Extruded to a size which allows for drying and
firing shrinkage
• Units are cut to the correct thickness by
tensioned wires

• For clays having very high moisture content
• Clay is pressed into moulds having sanded
surfaces to prevent the clay from sticking to
the surfaces of the mould

After bricks become in form,
then the identification or
perforation will occur to the
bricks.
Drying :
Wet unit bricks will be drying
in space or room with control
temperature to make sure
that the bricks completely
dry.
Brick compile before
taking to the kiln

Drying
• Drying is essentially evaporation of moisture either in
a normal atmosphere or with controlled humidity and
temperature.
• Drying is done prior to burning of bricks. The purpose
is to reduce the tendency of the bricks to distort or
crack while burning.
• Drying is slow, otherwise cracks may develop on its
surface. The process is usually take a number of days
(3 to 10 days).
• For artificial drying, this is done by drying bricks in
chambers or tunnels.
• Hot flue gases may be used to heat these chambers
or tunnels. Temperature is usually maintained at
120°C and the bricks get dried within 1 to 3 days.

Firing :
Dry bricks, compile in kiln to
start the firing process with
600o
C (temperature). This is
for burn the carbon and
sulfur that have remain.
After that, temperature will
increase to 900o
C to get a
verification process.
Normally, verification
process occurred around
800o
C.
Bricks become hard/strong
after verification process.
Beehive Kiln
Tunnel Kiln

30
Bricks manufacturing process flow

Quiz
• Why it is important that, the bricks meet
certain absorption requirements?
• Explain a method to measure the water
absorption on bricks.
• Explain the term of ‘tempering’ in clay bricks
preparation.

There are many types of
brick. Some are different
in formation and
composition while others
vary according to their use

brick is made of ordinary clays or
shale and burned in the usual
manner in the kilns. These bricks
do not have special scorings or
markings and are not produced in
any special color or surface texture.
Common brick is also known as
hard- and kiln-run brick. It is used
generally for backing courses in
solid or cavity brick walls. The
harder and more durable kinds are
preferred for this purpose.

bricks are used in the exposed face of a wall and are higher
quality units than backup brick. They have better durability
and appearance. The most common colors of face brick are
various shades of brown, red, gray, yellow, and white.

bricks that have been over burned in the kilns. This
type of brick is usually hard and durable and may be
irregular in shape. Rough hard corresponds to the
clinker classification.

made by the dry press process. This class of brick has regular
smooth faces, sharp edges, and perfectly square corners.
Ordinarily, all press brick are used as face brick.

bricks have one surface of each
brick glazed in white or other
colors. The ceramic glazing
consists of mineral ingredients
that fuse together in a glass-like
coating during burning. This
type of brick is particularly
suited for walls or partitions in
hospitals, dairies, laboratories,
or other buildings where
cleanliness and ease of cleaning
are necessary.

is made of a special type
of fire clay that will
withstand the high
temperatures of
fireplaces, boilers, and
similar usages without
cracking or
decomposing.
Firebrick is larger than
regular structural
brick, and often, it is
hand molded.

Are made with two rows of five holes extending
through their beds to reduce weight. There is no
significant difference between

• stretcher brick is a brick laid with the longest side exposed
• header brick is a brick laid with the smallest end exposed to the weather
• soldier is a brick laid on its end vertically

51
Header - Bonds two wythes together
Wythe: vertical layer 1 unit thick
Soldier - Laid on its end, face parallel
Rowlock -
laid on face,
end visible
Stretcher - long dimension horizontal
& face parallel to the wall

52
Basic Brickwork TerminologyBasic Brickwork Terminology
Bed
Joint
Head
Joint
Course - horizontal layer of brick

• Entirely comprised of stretcher bricks,
set in rows that are offset by half a
brick.
• Most common bond in modern time
• Can consist of one layer , two layers or
two layers with a gap in between
• The main advantage of this technique
is that it allows walls with both faces
visible, and can be used for : domestic
low-height walls where the part of the
structure above is built of a
lighter,framed material such as glass to
be built using low-cost bricks that have
only two fair faces

is made up of alternating courses of stretchers and headers. This produces
a solid wall that is a full brick in depth. English bond is fairly easy to lay and
is the strongest bond for a one-brick-thick wall. If only one face of an
English bond wall is exposed, one quarter of the bricks are not visible, and
hence may be of low visual quality.

(also known as Spanish bond) was a
very common bond for bearing walls.
It is composed of header bricks, set in
rows that are offset half a brick, which
produces a solid easy to lay bond
which is useful when building circular
work. It is the most used bond in
historical Spanish brick constructions.
Picture shows Header bond.

 Flemish bond, also known as Dutch bond, has historically always been
considered the most decorative bond, and for this reason was used
extensively for dwellings until the adoption of the cavity wall. It is created
by alternately laying headers and stretchers in a single course. The next
course is laid so that a header lies in the middle of the stretcher in the
course below. Again, this bond is one brick thick. It is quite difficult to lay
Flemish bond properly, since for best effect all the perpendiculars (vertical
mortar joints) need to be vertically aligned. If only one face of a Flemish
bond wall is exposed, one third of the bricks are not visible, and hence may
be of low visual quality. This is a better ratio than for English bond, Flemish
bond's main rival for load-bearing walls.
 A common variation often found in early 18th century buildings is Glazed-
headed Flemish Bond, in which the exposed headers are burned until they
vitrify with a black glassy surface. Monk bond is a variant of Flemish bond,
with two stretchers between the headers in each row, and the headers
centered over the join between the two stretchers in the row below.

Flemish bond photoFlemish bond photo

• These bonds are variations on normal bonds. They use a high proportion of
stretchers, and hence require fewer facing bricks than normal bonds. This makes
them less sturdy, but cheaper to lay. As such they are most commonly used for
garden- and other non-load-bearing walls.
• Flemish garden wall bond has a header alternating with (typically) three stretchers
in each course. Flemish garden wall bond was commonly used for garden walls in
southern England.
• English garden wall bond has a course of headers alternating with (typically) three
courses of stretchers. English garden wall bond was typically used in northern
England for buildings where English bond would have been used in southern
England, and not just for garden walls.
• Scottish bond has one row of headers to five of stretchers.
• American common bond is made by laying the courses of headers where they are
separated by approximately five to seven courses of stretchers. On occasion
American common bond can be found with nine courses of stretchers between
courses of headers. The stretcher courses are most often an uneven number.

Rat-trap bond, also known as Chinese bond, is a type of garden wall bond
in which the stretchers and headers are laid on their sides, with the base of
the stretcher facing outwards. This gives a wall with an internal cavity
bridged by the headers, hence the name. The main advantage of this bond
is economy in use of bricks, giving a wall of one brick thickness with fewer
bricks than a solid bond. Rat-trap bond was in common usage in England
for building houses of fewer than 3 stories up to the turn of the 20th
century and is today still used in India as an economical bond, as well for
the insulation properties offered by the air cavity. Also, many brick walls
surrounding kitchen gardens were designed with cavities so hot air could
circulate in the winter, warming fruit trees or other produce spread against
the walls, causing them to bloom earlier and forcing early fruit production.

• When bricks are laid on alternating angles, it is called a Herringbone.
This is primarily a decorative style, more often used for paving or
fireplace reflectors than for walls. It is generally considered
unsuitable for load-bearing structures, but may be found as infill in
traditional timber framed buildings. This style is also sometimes
called by its Latin name: Opus spicatum.

• This decorative pattern imitates the weave of a basket. It is also
sometimes called basket weave bond, and there are many
variations on the weave pattern, some very elaborate.

Decorative of brick work
Walk way

MORTAR
• A cushion and makes the masonry units toA cushion and makes the masonry units to
bear against one another and thus providesbear against one another and thus provides
strength to the wallstrength to the wall
• A seal in between the masonry units, andA seal in between the masonry units, and
keeps the water and air from penetrating itkeeps the water and air from penetrating it
• A bonding agent to make the individual unitsA bonding agent to make the individual units
to adhere to one anotherto adhere to one another
• A surface enhancer , proving beautifulA surface enhancer , proving beautiful
contrast and appearancecontrast and appearance

MORTAR (Cont’d)
• Mortar is made of Portland cement, hydratedMortar is made of Portland cement, hydrated
lime, and aggregates (sand) and water.lime, and aggregates (sand) and water.
Portland cement acts as bonding agent, limePortland cement acts as bonding agent, lime
imparts smoothness and workability, sandimparts smoothness and workability, sand
provides the bulk around which lime sets, andprovides the bulk around which lime sets, and
water provides workability to set brickswater provides workability to set bricks
properly. Setting of hydrated lime withproperly. Setting of hydrated lime with
absorption of COabsorption of CO22 from air makes the mortarfrom air makes the mortar
strongstrong

66
Mortar FunctionsMortar Functions
 Provides for full bearingProvides for full bearing
 Seals between masonry unitsSeals between masonry units
 Adheres / bonds masonry unitsAdheres / bonds masonry units
 AestheticsAesthetics

68
Brickwork StrengthBrickwork Strength
 Depends on:Depends on:
– Strength of the masonry unitStrength of the masonry unit
– Strength of the mortarStrength of the mortar

References
• http://www.glengerybrick.com/about/manufa
cturing/index.html
• http://brickcollecting.com/history.htm
• http://www.oldvirginiabrick.com/technical/bo
nd_patterns.html
• http://www.ixlbrick.com/index.php?
page=bond-patterns

Compressive strength test
• The specimen brick is immersed in water for 24
hours. The frog of the brick is filled flush with 1:3
mortar and the brick is stored under damp jute bags
for 24 hours followed by immersion in clean water
for three days. The specimen is then placed between
the plates of the compression testing machine. Load
is applied axially at a uniform rate of 14N/mm2
(140
kgf/cm2
) and the maximum load at which the
specimen fails is noted for determination of
compressive strength of brick given by
Compressive strength = max load at failure / loaded
area of brick

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