brick masonary
TRANSCRIPT
Brick Masonry
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Brick A brick is rectangular in shape and of size that can be conveniently handled with
one hand.
density of brick range= 2.5 – 2.8 g/cm3.
Modulus of elasticity = 5-30 N/mm2.
Size of brick = 19 x 9 x 9 cm or 19 x 9 x 4 cm.
An indent called frog 1-2 cm deep is provided
Size of frog = 10 x 4 x 1 cm.
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Ingredients of good brick earth
Sr no
Ingredients Limit (%)
1 Silica 50-60%2 Alumina 20-30%3 Lime 10%4 Magnesia
Ferric OxideAlkalis
< 1%<7%<10%
5 Carbon DioxideSulphur trioxideWater
Very small percentage
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Function of Various Ingredients
Silica
It enables the brick to retain its shape, impart durability, and prevent shrinkage and warping. Excess of silica makes the brick brittle and weak on burning.
Alumina
Absorb water and renders the clay plastic. If it present in excess, it produce crack in brick on drying.
Lime
Reduces the shrinkage on drying
Causes silica in clay to melt on burning and thus help to bind it
In carbonated form, lime lowers the fusion point.
Excess of lime causes the brick to melt and the brick looses its shape.
Magnesia
Affects the color and makes the brick yellow. In burning, it causes the clay to soften at slower rate than does lime and reduces warping.
Iron
Gives red color on burning when excess of oxygen is available and dark brown or even black color when oxygen available is insufficient. However, excess of ferric oxide makes the brick dark blue.
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Classification of Clay Bricks Based on field practice
Clay bricks are classified as first class, second class, third class and fourth class based on physical and mechanical properties.
First clay bricks
Thoroughly burnt and are of deep red, cherry or copper color
Surface should be smooth and rectangular, with parallel, sharp and straight edges and square corners.
Should be free from flaws, cracks and stones
Should have uniform texture
No impression should be left on the brick when a scratch is made by finger nail.
A metallic or ringing sound should come when two bricks are struck against each other.
Water absorption should be 12-15% of its dry weight when immersed in cold water for 24 hours.
The crushing strength should not be less than 10 N/mm2.
These bricks recommended for pointing, exposed face work in masonry structures, flooring and reinforced brick work.
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Cont’d… Second Class Bricks
Are supposed to have the same requirement as the first class bricks except that
Small cracks and distortions are permitted
A little higher water absorption of about 16-20% of its dry weight is allowed.
The crushing strength should not be less than 7.0 N/mm2.
These bricks are recommended for all important or unimportant masonry
works and centering of reinforced brick and reinforced cement concrete
structures
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Cont’d…
Third Class Bricks
These are under burnt. They are soft and light-colored producing a dull
sound when struck against each other. Water absorption is about 25%
of dry weight.
it is used for building temporary structures.
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Cont’d… On strength
On the basis of use : Common bricks, Facing Bricks, Engineering Bricks
On the basis of finish: Sand-faced bricks, Rustic Brick
On the basis of Manufacture: Hand Made, Machine Made
On the basis of Burning: Pale Bricks, Body Bricks, Arch Bricks
On the basis of types: Solid, Perforated, Hollow, Cellular
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Brick Masonry Brick masonry is made of brick units, bonded together with mortar. Two essential
components of brick masonry are therefore.
I. Bricks
II. Mortar
Mortar acts as a cementing material and unites the individual brick units together to
act as a homogeneous mass. Following types of mortar may be used in brick masonry.
1. Cement Mortar
2. Lime Mortar
3. Lime-Surkhi Mortar
4. Mud Mortar
5. Lime-Cement Mortar
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Cont’d… Cement mortar are used for high-rise buildings, where strength is of prime importance.
Lime mortar and lime-surkhi mortars are used for all types of construction
Mud mortar is used only for low-rise building which carry light loads.
Lime cement mortar known as guarded mortar or gauged mortar is made by mixing
cement and lime. The advantages are increased water retentivity, workability, bonding
properties and frost resistance. The mortar gives good and smooth plaster finish.
The chief properties of hardened mortar are strength, development of good bond with
building units, resistance to weathering and those of green mortar mixes are mobility,
playability and water retention. In addition, the mortar should be cheap and durable
and should not affect the durability of building units in contact. The joint made with
mortar should not develop cracks.
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Cont’d…
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Some Definitions
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Cont’d… Stretcher : A stretcher is the longer face of the brick (i.e. 19 cm x 9 cm) as seen in the
elevation of the wall. A course of brick in which all the bricks are laid as stretchers on
facing is known as a stretcher course or stretching course
Header : A header is the shorter face of the brick (i.e. 9 cm x 9 cm) . A course of bricks in
which all the bricks are laid as header on the facing is known as header course or
heading course.
Lap : Lap is the horizontal distance between the vertical joints of successive brick
courses.
Perpend: A perpend is an imaginary vertical line which includes the vertical joint
separating two adjoining bricks.
Bed: Bed is the lower surface (19cm x 9cm) of the brick when laid flat
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Cont’d…
Closer : It is a portion of a brick with the cut made longitudinally,
and is used to close up bond at the end of the course. A closer helps
in preventing the joints of successive sources (higher or lower) to
come in vertical line. Closer may be of various types, defined below.
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Cont’d… Queen Closer: it is a portion of a brick
obtained by cutting a brick lengthwise
into two portions. Thus a queen closer
is a brick which is half as wide as full
brick. This is also known as queen
closer half. When a queen closer is
broken into two pieces, it is known as
queen closer quarter. Such as closer is
thus a brick piece which is one quarter
of the brick size.
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Cont’d… King Closer
It is the portion of a brick which is so cut that the width of one its end is half that of a full brick, while the width at the other end is equal to the full width. It is thus obtained by cutting the triangular piece between the center of one end and the centre of the other side. It is half header and half stretcher face.
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Cont’d…
Beveled Closer
It is a special form of a king closer in which the whole length of brick (i.e. stretcher face) is beveled in such a way that half width is maintained at one end and full width is maintained at the other end
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Cont’d…
Mitred Closer
It is a portion of a brick whose one end is cut splayed or mitred for full width. The angle of splay may vary from 45° to 60°.
Thus one longer face of the mitred closer is of full length of the brick while the other longer face is smaller in length.
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Cont’d… Bat : it is the portion of the brick cut across the width. Thus, a bat
smaller in length than the full brick. If the length of the bat is
equal to half the length of the original brick, it is known as half
bat. A three quarter bat is the one having its length equal to three
quarter of the length of a full brick. If a bat has its width beveled,
it is known as beveled bat.
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Cont’d… Arris: it is the edge of the brick
Bull Nose: it is a special molded brick with one edge rounded (single bull nose) or with two edge round (double bull nose). These are use in copings or in such positions were rounded corners are preferred to sharp arises.
Splays: these are special molded bricks which are often used to form plinth. Splay stretcher (plinth stretcher) and splay header (plinth header)
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Cont’d… Dogleg or angle : it is also special form of molded bricks which
are used to ensure a satisfactory bond at quoins which are at an
angle other than right angle. The angle and lengths of the faces
forming the dogleg vary according to requirements. These are
preferred to mitered closer.
Quoin: it is a corner on the external angle on the face side of a
wall. Generally, quoin are at right angles. But, in some cases,
they may be at angle greater than 90°also.
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Cont’d…
Frog or kick
A frog is an indentation in the face of a brick to form a key for holding the mortar. When frog is only on one face, that brick is laid with that face on the top. Sometimes, frog are provided on both the faces. However, no frogs are provided in wire cut bricks. A pressed brick has two frogs and a hand made brick has only one frog.
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Cont’d… Racking Back: It is the termination of a wall in a stepped
fashion
Toothing: it is the termination of the wall in such a fashion that
each alternate course at the end projects in order to provide
adequate bond if the wall is continued horizontally at a later
stage.
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Bonds in Brick Work Bond is the interlacement of bricks, formed when they
lay (or project beyond) chose immediately below or above them. It is the method of arranging the bricks in courses so that individual units are tied together and the vertical joints of the successive courses do not lie in same vertical line. Bond of various types are distinguished by their elevation or face appearance. Bricks used in masonry are of all of uniform size.
If they are not arranged properly continuous vertical joint will result. An unbonded wall, with its continuous vertical joints has little strength and stability. Bonds help in distributing the concentrated loads over a larger area.
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Cont’d… Types of Bonds
Stretcher Bond Header Bond
English Bond Flemish Bond
Facing Bond English Cross Bond
Brick on edge bond Dutch Bond
Raking Bond Zigzag Bond
Garden wall bond
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Stretcher Bond In this bond all the bricks are laid as stretchers on the faces of
walls. The length of the bricks are thus along the direction of the wall. This pattern is used only for those walls which have thickness of half brick, such as those used in partition walls, sleeper walls, division walls or chimney stacks. The bond is not possible if the thickness of the wall is more
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Header Bond Header bond is the one in which all the bricks are laid as headers
on the face of walls. The width of the brick are thus along the
direction of the walls. The pattern is used only when the
thickness of the wall is equal to one brick. The overlap is kept
equal to half the width of the brick. This is achieved by using
three-quarter brick bats in each alternate courses as quoins. This
bond does not have strength to transmit pressure in the
direction of the length of the wall. As such it unsuitable for load
bearing walls.
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Cont’d…
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English Bond
This is the most common used bond, for all wall thickness. This
bond is considered to be the strongest. The bond consist of
alternate courses of header and stretchers. In this bond, the
vertical joints of the header courses come over each other.
Similarly, the vertical joints of the stretcher courses also come
over each other. In order to break the vertical joints in the
successive courses, it is essential to place queen closer after the
first header (quoin header) in each heading course. Also, only
header are used for hearting of thicker wall.
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Cont’d
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Cont’d…
Plan for I brick thick wall
1,3,5… Course
2,4,6 … Course
1,3,5… Course
2,4,6 … Course
Plan for I ½ brick thick wall
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Cont’d…
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Cont’d…
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Essential Features1. Alternative courses will show either headers or stretchers in
elevation
2. Every alternate header comes centrally over the joint between two stretchers in course below.
3. In the stretcher course, the stretchers have a minimum lap of 1/4th their length over headers.
4. There is no continuous joint
5. Wall of even multiple of half bricks (i.e. 1 brick thick wall, 2-brick thick wall, 3- bricks thick wall) present the same appearance on both faces. Thus a course showing stretchers on the front face will also show stretchers on the back face.
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Cont’d…5. Wall of odd multiple of half bricks (i.e. 1 ½ brick thick wall, 2 ½
brick thick wall etc.) will show stretchers on one face and
header on the other face.
6. The hearting (middle portion) of each of the thicker walls
consist entirely of header.
7. At least every alternate transverse joint is continuous from face
to face.
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Cont’d…8. A header course should never start with queen’s closer, as it will
get displaced. The queen’s closer should be placed just next to the
quoin header. Queen’s closers are not required in stretcher
courses.
9. Since the number of vertical joints in the header course are twice
the number of vertical joints in the stretcher course, the joint in
the header course are made thinner than the joints in the
stretcher course.
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Flemish Bond In this type of bond, each course is comprised of alternate headers
and stretchers. Every alternate course starts with a header at the
corner (i.e. quoin header). Quoin closer are placed next to the
quoin header in alternate courses to develop the face lap. Every
header is centrally supported over the stretcher below it.
Flemish bond are of two type.
Double Flemish Bond
Single Flemish Bond
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Cont’d… In the double Flemish bond, each course presents the same
appearance both in the front face as well as in the back face.
Alternate headers and stretcher are laid in each course.
Because of this, double Flemish bond present better
appearance than English bond
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Cont’d…
S H S HQ
S
S
S
H
H
H
H
Q
Q
Q
S
S
S
S
H
H
H
H
H
H
H
H
S
S
S
S
Fig- Double Flemish Bond (Elevation)
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Cont’d… Special Features of Double Flemish Bond
1. Every course consists of headers and stretchers placed alternately
2. The facing and backing of the wall, in each course, have the same
appearance
3. Quoin closer are used next to quoin headers in every alternate course.
4. In wall having thickness equal to odd multiple of half bricks, half bats
and three quarter bats are amply used.
5. For walls having thickness equal to even multiple of half brick, no bats
are require. A header or stretcher will come out as header or stretcher
on the same course in front as well as back faces.
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Cont’d…
Fig: Double Flemish Bond
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Cont’d…
Double Flemish Bond
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Cont’d…
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Single Flemish Bond Single flemish bond is comprised of double flemish bond
facing and English bond backing and hearting in each course. This bond thus used the strength of English bond and appearance of flemish bond. However this bond can be used for those walls having thickness at least equal to 1 ½ brick. Double flemish bond facing is done with good quality expensive bricks. However cheaper bricks can be used for backing and hearting.
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Cont’d…
Q
1,3,5 -----Course
2,4,6 -----Course
S
S S S
HB3 B2
H
S = StretcherQ= Queen’s CloserB2 = Half Bat B3 = ¾ Brick; B1 = Quarter Bat
Q
S H S H S
B3
S
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Cont’d… Comparison of English Bond and Flemish Bond
1. English bond is stronger than Flemish bond for wall thicker than 1
½ brick.
2. Flemish bond gives more pleasing appearance than the English
bond
3. Broken bricks can be used in the form of bats in Flemish bond.
However, more mortar is required.
4. Construction with Flemish bond requires greater skill in
comparison to English bond.
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Facing Bond This bond is used where bricks of different thickness are to be used
in the facing and backing of the wall. In this bond, a header course is
provided after several stretcher course. Since the thickness of
bricks are different in the facing and backing, the vertical distance
between the successive header course is kept equal to the least
common multiple of the thickness of backing and facing bricks.
Thus, if the nominal thickness of facing bricks is 10 cm and that of
backing bricks is 9 cm, the header course is provided at a vertical
interval of 90 cm. this type of bond is not structurally good and load
distribution is not uniform.
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English Cross Bond This is a modification of English bond, used to improve the
appearance of the wall. This bond combines the requirements
of beauty and strength. Special features of the bond are as
follows:
1. Alternate courses of header and stretchers are provided as in
English bond
2. Queen closer are placed next to quoin headers
3. A header is introduced next to the quoin stretcher in every
alternate stretcher course.
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Cont’d…
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Brick on Edge Bond This type of bond uses stretcher bricks on edges instead of bed.
This bond is weak in strength, but is economical. Hence it is used for garden walls, compound walls etc. Bricks are kept standing vertically on end. The bricks are arranged as headers and stretchers in such a manner that headers are placed on bed and stretchers are placed on edge thus forming a continuous cavity. Due to this, the bond consumes less number of bricks.
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Dutch Bond This is another modified form of English Bond. In
this bond the corners of the wall are strengthened. Special features of this type of bond is as follows.
1. Alternative courses of headers and stretchers are provided as in English bond.
2. Every stretcher course start at the quoin with a three-quarter bat.
3. In every alternate stretcher course, a header is placed next to the three-quarter brick bat provided at the quoin.
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Cont’d…
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Raking Bond This bond is used in thick wall. In this type of bond, the bonding bricks are kept
at an inclination to the direction of the wall. Due to this, the longitudinal stability of thick wall built in English bond is very much increased. This bond is introduced at certain intervals along the height of the wall. Special feature of raking bond is
1. The bricks are arranged in inclined direction, in the space between the external stretchers of the wall
2. The raking or inclination should be opposite direction in alternate courses of raking wall.
3. Raking bond is not provided in successive courses. It is provided at a regular interval of four to eight courses in the height of a wall
4. The raking course is generally provided between the two stretcher courses of the wall having thickness equal to even multiple of half- bricks, to make the bond more effective.
Raking bonds are of two types:
Diagonal bond Herring-bone bond
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Cont’d…
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Zig Zag Bond This bond is similar to herring-bone bond, except that the
bricks are laid in zig-zag fashion. This bond is commonly
used for making ornamental panels in the brick flooring
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Cont’d…
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Garden Wall Bonds
As the name suggests, this type of bond is used for the construction of garden walls, boundary walls, compound walls, where the thickness of wall is one brick thick and the height does not exceed two meters. This type of bond is not so strong as English Bond, but is more attractive. De to this reason, it is sometimes used in the construction of outer leaves of cavity walls. Garden wall bonds are of three types:
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Cont’d… Garden wall English bond Garden wall Flemish bond Garden wall Monk bond
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Cont’d…
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Junctions
Junctions is that connection which is formed at the meeting of one (subsidiary) wall at same intermediate position of another wall. When both these walls meet at right angles, we get a tee-junction, we have a cross-junction or intersection. However, if the subsidiary wall meets the main wall at some intermediate point, and if the angle formed between the two is other than a right angle, a squint junction is formed.
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Cont’d… Junctions are of the following types: (a) Right angled junctioni. Tee Junctionii. Intersection or cross junction (b) Squint junction
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Tee Junction (a) External and Internal walls in English
Bond
Tee junction is formed when the internal walls at its end meets external wall at some intermediate position. Tee-junctions can be either in English bond or in Flemish bond
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Cont’d… Figure shows a one-brick thick
external wall and a half brick thick internal wall (partition wall), both walls being constructed in English bond. Bond is obtained by making alternate courses of internal wall entering into the stretcher course of the main wall. Due to this, lap of half brick is obtained through the brick (shown shaded). Alternate courses of both the walls remain unbonded
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Cont’d… Figure shows the tee junction
between 1 ½ brick thick external wall and one-brick thick internal (cross) wall, both the walls being constructed in English bond. Here, the header course of internal wall centers the stretcher course of the main through half of its width. Due to this, lap of quarter –brick is obtained through the tie-brick, which is placed near the queen closer (Q). Alternate course of both the walls remain unbonded.
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Cont’d… It shows the Tee-junction between
1 ½ brick thick external wall and 1 ½ brick thick internal wall, both the walls being constructed in English bond. In alternate courses, the header brick at the junction enters the stretcher courses of the main wall. The tie-brick (shown shaded), placed near the queen closer (Q) furnishes a lap of quarter brick. Additional courses of both the walls remain unbonded.
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Cont’d… Figure shows the Tee-junction between
2- brick thick main wall and 1 ½ brick thick cross wall, both the walls being constructed in English bond. Here the header course of internal wall enters the stretcher course of the main wall through half of its width. Due to this, lap of quarter brick is obtained through the tie-brick (header brick) which is placed near the queen closer (Q). Additional lap is obtained in the same course, through placing a ¾ brick bat. Here also, alternate courses of both the walls remain unbonded.
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External wall in Flemish bond and internal wall in English bond
It shows the Tee-junction for a brick
thick external wall in Double Flemish
bond and one brick thick internal
wall in English bond. The header
course of internal wall enters into the
main wall, thus getting a lap of one-
quarter brick. The tie-brick (header
course) is placed adjacent to a queen
closer. Alternate courses of both the
walls remain unbonded.
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Cont’d Figure shows the Tee-junction for 2 brick
thick external wall in Double Flemish bond
and 1 ½ brick thick internal wall in English
bond. Here also, the header course of the
cross wall (internal wall) enters the main
wall, thus getting a lap of quarter brick. The
tie brick (header brick) is placed next to a
queen closer. Additional lap is obtained
through the stretcher brick of the same
course of the internal wall, which is placed
adjacent to a ¾ brick bat of the main wall.
The alternate courses of both the walls
remain unbonded.
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Both external and internal walls in double Flemish bond
Figure shows the Tee- junction for a 1-brick thick main wall and ½ brick
thick cross wall, both being constructed in Double Flemish bond. The
stretcher bricks of alternate courses of the cross wall enter into the main
wall through half brick length. Due to this, it is necessary to place a half-
brick bat adjacent to it, in the main wall. The alternate courses of each
wall remain unbonded.
B2 = Half Brick
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Cont’d… Figure shows the Tee-junction for
a 1 ½ brick thick main wall and one-brick thick cross wall, both being constructed in double Flemish bond. In alternate course, the stretcher bricks of the cross wall enter into the main wall through quarter brick. A queen closer (Q) is placed next to it in the main wall. Alternate courses of both the walls remain unbonded
B2 = Half BrickQ= Queen Closer
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Cont’d… Figure shows the Tee-junction
for two-brick thick main wall and 1 ½ brick thick cross-wall. Bonding is obtained through a lap of one-quarter brick. It is essential to use a queen closer and a ¾ brick bat in the main wall, at the alternate courses in which both the walls are bonded.
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Cross Junction or Intersection
A cross-junction is formed when two internal walls cross each other at right angles. One of the walls may be called as the main wall while the other of lesser thickness as cross wall.
Figure (a) shows a cross junction between 1 ½ brick thick main wall and 1 brick thick cross-wall, both being constructed in English bond. The header course of cross-wall enter into the main wall: the tie bricks thus give a lap of quarter brick on both sides. Alternate courses of both the walls remain unbonded.
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Cont’d…
Fig. (b) shows a cross junction between two walls, each of 1 ½ brick thick constructed in English bond. A lap of quarter brick is obtained through header courses, on both the sides. Alternate courses thus remain unbonded.
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Cont’d… Fig. (c) shows a cross junction
between a 2 brick thick main wall and 1 ½ brick thick cross wall. A quarter brick lap is obtained on both sides thick main wall and 1 ½ brick thick cross wall. A quarter brick lap is obtained on both sides through the header course. Additional lap is also obtained through ¼ stretcher brick on one side and ¾ stretcher brick on the other side. Alternate courses of both the walls remain unbonded.
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Squint Junction A squint junction is formed when an internal wall meets
an external continuous wall at an angle other than 90°. Usually, the angle of squint is kept at 45°, though squint junctions are not very common in brick work.
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Cont’d… Fig. show a squint junction
between 1 ½ brick thick external wall and a 1 brick thick internal wall, both being constructed in english bond. The header courses of the cross-wall is taken inside the main wall, thus getting the required bond. Alternate courses of both the walls remain unbonded.
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Cont’d…
Fig. (b) shows a squint junction between two walls each of 1 ½ brick thickness and constructed in English both. The header bricks are taken inside the main wall. Alternate courses remain unbonded.
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Squint junction in Double Flemish bond
Fig. Shows the squint junction for the walls constructed in Double Flemish bond. These junctions are quit difficult to be constructed.
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Load Bearing Walls Load bearing walls are those which are designed to
carry super-imposed loads (transferred through roofs etc.,) , in addition to their own weight (self weight). Non-load-bearing walls carry their own load only. They generally serve as divide walls or partition walls. The external non-load bearing wall, commonly related to framed structure is termed as panel wall.
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Cont’d… Load bearing walls may further be divided into following steps
a) Solid masonry wall
b) Cavity wall
c) Faced wall
d) Veneered wall
Solid Masonry Wall
It is one most commonly used. These walls are built of individual blocks of material, such as bricks, clay or concrete blocks, or stone, usually in horizontal courses, cemented together with suitable mortar. A solid wall of the same type of building units throughout its thickness. However, it may have opening for doors, windows etc.
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Cavity Wall A cavity wall is a wall comprising two leaves, each leaf
being built of structural units and separated by a cavity and tied together with metal ties or bonding units to ensure that the two leaves act as one structural unit. The space between the leaves is either left two leaves act as one structural unit. The space between the leaves is either left as a continuous cavity or is filled with non-load-bearing insulating and water proofing material
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Faced wall It is a wall in which the facing and backing are of two
different materials which are bonded together to ensure common action under load
Veneered wall
It is a wall is a wall in which the facing is attached to the backing but not so bonded as to result in a common action under load.
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Cont’d… In order to carry vertical loads, the wall has to be
continuous from top to bottom. Ideally, openings should be rather narrow and in-line vertically, rather than wide or haphazardly located on the elevation.
Since walls rely on intersecting with each other to provide some of their stability, continuous vertical openings would turn the wall into a series of isolated piers. This layout would only be efficient if the floors each served to tie the separate piers together at each level.
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Cont’d…
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Stability of load bearing walls
In order to resist the horizontal loads, walls rely on either their own thickness, or the support provided when two walls meet at right angles. In modern buildings there is no need to use the very thick walls and adequate stability can usually be achieved either by having a lot of intersecting walls or by articulating the wall itself to provide both strong modelling and stability.
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Cont’d…
The principal vertical loads acting on any wall will be its own weight, and if it is load bearing, also the loads from parts of the building's floors and roofs. It must be able to support these loads.
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Cont’d… An external wall will be subjected to horizontal wind
loads. It must be able to resist the effect of the wind, which will be either to overturn the wall as a unit, or to bend a panel of walling inward or outward between its supports. In this respect, a load bearing wall is stabilized to some extent by the effect of the vertical load on top of it. Because of being attached to a floor or roof structure at the top of the wall, it also is stabilised more than a freestanding wall would be.
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Cont’d…
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Multi-storey load bearing buildings
Buildings up to 10 or 12 storeys have been constructed from loadbearing brickwork, both in Australia and overseas. In these cases the structural requirements become more severe, both because of the additional load of the building, and also because of the increased effect of wind loads. Usually the strength of the bricks and of the mortar have to be increased, and it is common for the lower storeys to require full-brick (230mm) thick walls, at least in parts.
Many brickworks can and do produce high-strength bricks, but if they are required to test and certify them at a particular strength, the cost will increase, and the range of colours and finishes might be reduced. Testing and certification of the mortar strength and the techniques of laying (such as ensuring full bed joints) might also add something to the cost. On the other hand, in a multistorey building with an appropriate plan layout, the use of loadbearing brick walls can save the cost of a separate structural frame, and of the details where the walls abut columns and beams
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Cont’d…
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Non-Load bearing Walls The base of the walls in large nineteenth-century buildings were quite thick
(up to a meter or more), because of the heavy loads to be carried and, before the use of cement mortar, the low strength of the joints. Modern masonry walls can be made to carry considerable loads by the use of high-strength bricks and mortar, but often a framed structure allows more freedom in the design of the facade as well as in the planning of the interior.
A structural frame of reinforced concrete or steel can support the loads of the floors and roof, and also of the non-load bearing walls. The external walls then perform all the 'enclosure' functions. Each wall panel also carries its own weight and resists wind and seismic loads, but only those that act on the panel itself.
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Wednesday, May 3, 2023
THAPAR UNIVERSITY, PATIALA 92
Arrangement of supports
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Brick Panel Walling A wall panel is single piece of material, usually flat and
cut into a rectangular shape, that serves as the visible and exposed covering for a wall. Wall panels are functional as well as decorative, providing insulation and soundproofing, combined with uniformity of appearance, along with some measure of durability or ease of replacability. While there is no set size limit for a piece of material fulfilling these functions, the maximum practical size for wall panels has been suggested to be 24 feet by 8 feet, to allow for transportation
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Cont’d… Use of wall panels can reduce construction costs by
providing a consistent appearance to the paneled surface without requiring the application of paint or another finishing material. Wall panels may be finished on only one side, if the other side is going to be against a brick or concrete wall, or a comparable structure. Alternately, the panels may, if assembled to an appropriate framework, substitute for having any other kind of wall at all. Holes may be cut or drilled into a wall panel to accommodate electrical outlets and other devices coming out of the wall.
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Cont’d…
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Reinforced Masonry Reinforced brick work is the one in which the brick masonry is
strengthened by the provision of mild steel flats, hoop iron, expended mesh or bars. It is adopted or used in the following circumstances:
1. When the brick work has to bear tensile and shear stresses
2. When it is required to increase the longitudinal bond.
3. When the brick work is supported on soil which is susceptible to large settlement
4. When the brick work is supposed to act as a beam or lintel over
opening.
5. When the brick work is to resist lateral loads, such as in retaining walls etc.
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Cont’d…6. When the brick work is to carry heavy compressive
loads.
7. When the brick work is to used in seismic areas, since it can also resist lateral loads.
Reinforced brick work uses first class bricks with high compressive strength. Dense cement mortar is used to embed the reinforcement. The reinforcing material may be (i) hoop steel bars, (ii) mild steel bars (iii) mild
steel flats (iv) Expended metal. The reinforcement is laid either horizontally or vertically.
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Horizontal Reinforcement Horizontal Reinforcement for wall
consists of either (i) wrought iron
flat bar, known as hoop iron, or (ii) steel mesh.
Fig shows hoop iron reinforcement for a brick wall. Generally, two strips of hoop iron
are used per header brick and
one hoop iron per stretcher brick i.e., one strand of hoop iron for each half brick thickness of wall
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Cont’d… Mild steel flats may also be
used in place of hoop iron. It is usually to reinforce every 6th
course (width 22 to 32 mm and thickness 0.25 to 1.6mm). Protection against rust is
provided by dipping the bars in
hot tar; these are then at once sanded to increases the adhesion of the mortar.
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Cont’d… Another form of horizontal r/f, which is more
commonly used, is the provision of steel
meshed strips called Exmet (Expended
Metal). It is provided at every third course. Sizes available are (width 65 mm, 178 mm and 230 to 305 mm, with thickness of 0.6 mm, 0.8 mm and 1 mm). To prevent the corrosion, the
metal in the coil form is coated with oil and
then dipped in asphaltum paint. Cement mortar is first trowelled on the bed and the Exmet is uncoiled and pressed down in the mortar. Another form of meshed r/f, called bricktor, is made of a number of straight tension wires (1.4 mm) interlaced with binding wires (1.1 mm). One such strip is provided for
every half-brick thickness of wall.
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Cont’d… Horizontal reinforcement is also used
for brick lintels as shown in fig. Generally mild steel bars (6mm to 12
mm) are provided, through the
vertical joint, all along the span of
lintel. If the lintel carries heavy
loads, resulting in heavy shear force,
6mm dia. Steel wire stirrups are
provided at every 3rd vertical joint. The longitudinal steel bars (main
reinforcement) should extend 150
mm beyond the jambs.
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Vertical reinforcement Vertical reinforcement, in the form
of mild steel bars, is provided in
brick columns, brick walls and
brick retaining walls. In such a circumstances, special bricks, with one or two holes extending upto the face, are used. Vertical
mild steel bars are then placed in
the holes. These bars are
anchored by steel plate or wire-tie
bars at some suitable intervals.
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Cont’d… Brick retaining walls are often reinforced
since such a work is cheaper than the RCC, when the height of the wall is upto 3 m. Vertical reinforcing bars are placed vertically near each face, in addition to steel meshed stris at every fourth course. The bricks opposite each bar are purpose made, having a groove. The size of the groove is kept slightly more than the diameter of the bar so that it may be grouted in with cement mortar, to prevent corrosion. Steel wire ties may be provided at every fourth course.
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Cont’d… In all type of reinforced brick work, it is essential to
embed the steel reinforcement in rich cement mortar (usually 1:3), with proper cover so that reinforcement is not corroded. Corrosion will result in expansion of the joint and consequent cracking. The bricks should also be of high quality, possessing high compressive strength so that optimum use is made of all the materials (i.e., bricks, mortar and reinforcement).