1 Stone Masonry

Introduction
Stone is an economical material used in the construction
of buildings and various building parts. In some parts of
our country, stones are abundantly available in nature.
These are cut and given different shapes as per the need.

Categories of Stone
Stones are categorised depending on their use in the
construction of building structures and location. The
categories of stone have been discussed as follows.
Selection of stones for masonry depends on the
availability, ease of working, appearance, strength
and stability, polishing characteristics, economy and
durability.
Table 1.1: Stones used for different purposes
S.No. Purpose Stone used
1. Heavy engineering work, Granite and gneiss
e.g., docks, breakwaters,
lighthouses, bridge piers
2. Buildings situated in Granite and
industrial towns compact
sandstones
 Pavements railway ballast,
3. Granite and ballast
door sills and steps

4. Fire resistance works Compact sandstone

5. Carving and ornamental works Marble and laterite

Marble, granite
Facelift and architectural
6. and closer grained
purposes
sandstone

Sill
It is the bottom surface of a door or window opening
Sill
(Fig. 1.1). Sill stones are dressed in a way that they
prevent the entry of water into the building.
Fig. 1.1: Sill

Corbel
It is a projecting stone, which is used to provide support
to roof truss, beam and weather sheds, etc. (Fig. 1.2).
Corbels are, generally, moulded and given ornamental
treatment. The corbels should extend at least two-third
of their length into a wall.
Fig. 1.2: Corbel Cornice
It is a decorative border around the top of walls
in a room or on the outside walls of a building. In
Coping other words, it is the uppermost horizontal area that
appears like moldings along the top of a wall or just
below a roof line. Stone is used to make cornice.
Cornice overhang is used to protect the building’s
walls. It is, usually, painted to make it waterproof and
weather resistant.

Coping
To protect the walls of a building from rainwater, a course
of stones are laid at the top of the wall or parapet wall.
It is known as ‘coping’. These stones are weathered and
threaded for better resistance and durability (Fig.1.3).

String Course
When a horizontal projected course of masonry is
Fig. 1.3: Coping provided between the plinth and cornice, it is called

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 ‘string course’. The purpose of string course is to provide
architectural features, as well as, to check rainwater
impact in buildings.

Through Stone
It refers to a stone that is set with its longest
dimension perpendicular to the face of a wall and the String
length of which is equal to the thickness of the wall
Fig. 1.4: String course
(Fig.1.5). Such stones are known as through stones.
The through stone should be strong and of sufficient
thickness so as to avoid the danger of fracture due to
any slight settlement of the wall.

Classification of Stone Masonry

Based on the arrangement of stones in construction and
degree of refinement in the surface finish, stone masonry
Fig. 1.5: Through stone
can be classified into rubble and ashlar masonry.

Rubble Masonry
In rubble masonry (also called rubble‑work), stones of
irregular sizes are used in construction of walls. The
stones, as obtained from quarry are broken with the
help of a hammer. The strength of rubble masonry
depends on these factors.
• Quality of mortar
• Use of long through stones at frequent intervals
• Proper filling of mortar in space between stones

Classification of rubble masonry

Rubble masonry is classified into the following
categories:
(a) Coursed rubble
(b) Uncoursed rubble
(c) Random rubble
(d) Dry rubble
(e) Polygonal rubble
(f) Flint rubble

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 Coursed rubble
This type of masonry is commonly used
in the construction of low height walls
of public and residential buildings,
abutment and piers of ordinary bridges.
In this type of masonry, the height of
stones varies from 5 to 200 mm. The
masonry work carried out in this course
is such that the height of stones in a
particular course should be the same.
Coursed rubble masonry is further
divided into three categories.
Coursed rubble masonry—Class I
Fig. 1.6: Coursed rubble masonry
In this type, stones of the same height
are used and the courses are also of the
same heights (Fig.1.7).
Coursed rubble masonry—Class II
This type is similar to Class I, except that:
• the stones to be used are of
different heights.
• the courses need not to be of
equal heights.
Fig. 1.7: Coursed rubble
masonry—Class I • only two stones are to be used
to make up the height of one
course.
• the thickness of mortar joint is
12 mm.
Coursed rubble masonry—Class III
This type is similar to Class I, except that:
• the stones to be used are of
Fig. 1.8: Coursed rubble different heights, the minimum
masonry—Class II being 50 mm.
• the courses need not be of equal
heights.
• only three stones are to be used
to make up the height of one
course.
• the thickness of the mortar joint
is 16 mm.
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 Uncoursed rubble masonry
When stones from quarry are used
without any dressing, except knocking
out some coarseness, then it is known
as uncoursed rubble masonry. The
courses are not uniformed and no
maintenance is required. In this
masonry, larger stones are fixed in
bottom and spaces between these
stones are filled up by means of Fig. 1.9: Uncoursed rubble masonry
small stones known as spall (Fig.
1.9). The height of wall made with
this masonry can vary from 30 cm to
50 cm. This rubble masonry is used
for construction of compound walls,
garages, godowns, etc. Cost of this
masonry is the cheapest.
Elevation Section
Random rubble masonry Fig. 1.10: Random rubble masonry

This type of masonry consists of stones

of irregular sizes and shapes. The
stones are arranged in such a pattern
that gives good appearances. It is a
specialised job and requires skilled
personnel to make the structure
stable.
Uncoursed random rubble masonry Fig. 1.11: Uncoursed random rubble masonry
is made by stacking stones of different
sizes and qualities. Weak corners
and edges of the stone are removed
by hammer.
Dry rubble masonry
In this masonry, no mortar is used
in joints. It is similar in construction
to coursed rubble masonry. This type
of construction is the cheapest but it
requires more skill in construction. It is
preferred for compound walls pitching
on bridge approaches, retaining walls, Fig. 1.12: Dry Rubble Masonry

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 etc. To avoid displacement of stones,
two courses at the top and about 50
cm length at the ends may be built
in mortar.
Polygonal rubble masonry
It is a technique of stone wall
construction. In this masonry, visible
surfaces of the stones are dressed in
such a way that the block appearance
looks like a polygon. It is a special
technique of masonry. More skill is
Fig. 1.13: Polygonal rubble masonry
required in the construction of this type
of masonry.
Flint rubble masonry
In this type of masonry,
Coursed
the stones used are
Lacing course called flints. The flint
stones varying in
1 to 2 thickness from 8 to
m Uncoursed
15 cm and in length
from 15 to 30 cm, are
Lacing course arranged in the form of
coursed or uncoursed
Fig. 1.14: Flint rubble masonry masonry. In the case
of buildings in coastal
areas, the rounded flints procured
from beaches are used. The joints of
flint rubble masonry are slightly raked
back with a pointed stick to improve the
appearance.

Ashlar Masonry
This is considered to be a superior
quality of masonry. This is built from
accurately dressed stones with uniform
and very fine joints. The various types
of ashlar masonry can be classified as:
(a) Ashlar fine
Fig. 1.15: Ashlar Masonry
(b) Ashlar rough tooled

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 (c) Ashlar rock or quarry faced
(d) Ashlar chamfered
(e) Ashlar facing
(f) Ashlar block in course

Ashlar fine
At all beds joints and faces stones
should be dressed perfectly so that
they confirm to the desired pattern (Fig.
1.16). The stones are arranged in proper Fig. 1.16: Ashlar Fine
bond and the thickness of the mortar
joint does not exceed 3 mm. This gives
perfectly smooth appearance but it is
costly in construction.

Ashlar rough tooled

The size of stones bond, etc., have similar
specification as described in case of
ashlar fine masonry. The exposed face
of this masonry should be given a fine
dressed, chisel drafting of about 25 mm
Fig. 1.17: Ashlar rough tooled masonry
in width. The thickness of mortar joint
does not exceed 6 mm.

Ashlar rock or quarry faced

In this type of masonry, the exposed
faces of the facing stones between
the chisel drafting all around are left
undressed. However, the projections
of size more than 8 cm are broken. All
other specifications are kept similar to
that of ashlar rough tooled masonry.
This type of construction gives Fig. 1.18: Ashlar rock or quarry faced
massive appearance.

Ashlar chamfered
The specifications regarding size bonds
and the type of joints are similar to the
one as described above. The exposed
edge of stones are levelled for a depth of
about 2.5 cm (Fig.1.19).
Fig. 1.19: Ashlar Chamfered

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 Ashlar facing
In this type of construction the facing is constructed in
ashlar masonry and the backing may be on the brick
masonry, rubble masonry or concrete masonry. This
arrangement of masonry leads to saving of material
and money. The height of course should be more than
200 mm. The facing stones are either rough tooled or
chamfered.

Ashlar block in course

This type of masonry occupies an intermediate position
between rubble masonry and the ashlar masonry. The
faces of the stones are generally hammer dressed and
thickness of mortar joint does not exceed 6 mm. This
type of construction is used for heavy engineering works
such as retaining wall, sea wall, etc.

Joints in Stone Masonry

The joints in stone masonry can be broadly categorised
in the following types.
(1) Butt or squared joint
(2) Rebated or lapped joint
(3) Tongued and grooved joint
(4) Tabled joint
(5) Saddled joint
(6) Rusticated joint
(7) Plugged joint
(8) Dowelled joint
(9) Cramped joint
(10) Flushed joint

(1) Butt or Squared Joint

Fig. 1.20: Butt joint
This is a common joint and is extensively used for usual
tasks. Square surface of one stone is placed against that
of another stone in this joint. (Fig. 1.20)

(2) Rebated or Lapped Joint

Rebates are used in these joints. These rebates prevent
Fig. 1.21:Rebated joint the movement of stones. The length of rebate varies

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 as per the requirement, but it should not be less
than 70mm.

(3) Tongued and Grooved Joint

In this joint, a projection of one stone gets fitted in
the adjoining stone. Both stones get joined with
the depression or groove. This arrangement reduces
the sliding of one stone over the other. This is also
known as joggle joint.

(4) Tabled Joint

To check the lateral movement of water through the
bed of the stone, a joggle joint is used. This joint Fig. 1.22: Bed joint or
tabled joint
is mostly used where lateral pressure is heavy, like
the structure of sea walls.

(5) Saddled Joint

To protect the joints or
cornices from rain water,
the stone is rounded off, it
is known as saddled joint. It
diverts the water moving on
the weathered surface from
the joints. Vee Joint Channeled Joint

(6) Rusticated Joint

In this type of joint the edges
of the joints are sunk below
the plane of face work. The
different types of rusticated
joints can be—channeled Moulded Joint Vee and Channeled Joint
joint, vee joint, and vee and Fig. 1.23: Rusticated or rebated joint
channeled joint.

(7) Plugged Joint

It can also be used in place of cramped joints.
In this joint, dovetail shaped mortises are
kept in the sides of adjacent stones. They are
sealed by pouring molten lead in the joint. The
Fig. 1.24: Different forms of plug joints
stones get connected firmly when molten lead
becomes cool.

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 (8) Dowelled Joint
Stone
Dowels In this type of joint, a
hole is made into every
stone in which small
pieces of hard stone,
slate, gun-metal brass,
Fig. 1.25: Dowel Joint
etc., are inserted and
Rich cement mortar then sealed with cement.
Iron cramp
Lead (9) Cramped Joint
When two stones are
joined with the help
of metal cramps, then
this joint is known as
cramped joint. This joint
Fig. 1.26: Cramp joint checks the stones to get
away from each other.
Cramps are made up of non-corrosive
metals. Cramps are inserted in stone
40–50 mm. The length, width and
thickness of the cramps vary from 20
to 30 cm, 25 to 50 mm and 5 to 10 mm,
respectively.

(10) Flushed Joint

Underpinned joint Flushed jointIt is used in brick wall construction,
Fig. 1.27: Underpinned and Flushed joint when the surface requires plastering
and final finishing. Thus the flushed
joint will be hidden. Construction of flushed joints
takes more time and work to make it watertight and
water resistant.

Maintenance of Stone Masonry Construction

Stone masonry construction should be maintained with
respect to the following:
(1) Stains
(2) Efflorescence
(3) Cracks
(4) Waterproofing

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 Stains
The stains on stone work can be iron stains, copper
stains, smoke and fix stains, oil stains, tobacco stains
and ink stains.
Iron stains can be removed by washing the stained
area with the solution of oxalic acid mixed in water
(1 kg of oxalic acid mixed with 10 litres of water). The
stained area is rubbed with brush and water after
three to four hours. In order to remove dark and
deep stains, a solution having one part of sodium
citrate mixed with six parts of water is sprinkled.
This surface is then covered with a thin layer of
sodium hydrosulphide. The surface is washed after
an hour.
Copper and bronze stains are removed by
application of ammonium chloride solution (one part of
ammonium chloride, four parts of powdered talc) with
ammonia water.
Smoke and fix stains are treated with powdered
pumice or grit. The surface is rubbed several times
and cleaned.
Oil stains are treated with benzene or petrol. In order
to remove deep oil stains, a mixture of acetone and amyl
acetal is used. A dilute solution of trisodium phosphate
can be used to remove the tobacco stains.
Chlorinated lime, ammonia water or concentrated
solution of sodium perborate can be used to remove the
ink stains.

Efflorescence
The stones to be used for masonry work should be kept
saturated with water so that they may not get discoloured
because of acid action. Efflorescence is common with
certain types of stones and can be prevented by having
proper drainage in the building.

Cracks
There can be small as well as large stone masonry
cracks. Small cracks canbe cleaned with wire brush
and filled with thick paste of cement mix.

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 Large cracks canbe raked out to get a firm key for the
mortar. For this an inverted groove of at least 10 mm
depth is required. A cement sand mortar of 1:2 ratio
with less water is applied within an hour after mixing.
Aluminium may also be added in the mixture to make
it a tight fit.

Waterproofing
Application of waterproofing material makes the
stone masonry free from efflorescence, dampness,
frost action, etc. Generally heavy petroleum
distillate, fatty oil or insoluble soap serve as
excellent waterproofing matter. These materials are
applied as a washing coat; they may cause some
temporary discolouration.

Laying of Stone Masonry

Points to be considered during construction
• The stone should be hard, tough and durable.
• The stones should be well watered before use.
• There should not be any hollow space inside the
wall.
• Through stones (headers) should be used in
successive layers, at 1 m (3’ to 5’) to 1.5 m apart,
both ways.
• Use artificial header (R.C.C.) in case of more
width.
• Care should be taken to secure a good mortar
bond throughout the masonry (approximately
20mm i.e. ¾”). Corner stones are prepared from
the mason’s hammer.
• The joints should not be too smooth, to prevent
the stones from sliding down.
• The wall should be truly vertical.
• Minimum 12mm (½”) margin should be provided
in column external face and masonry, to avoid
the offset of rubble in plinth masonry after the
plaster.

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 • Old work should be cleaned and watered before
starting any new work on it.
• Keep expansion joint at 15m interval, in case of
a compound wall.
• Lay some vertical stones in masonry for better
bonding of the first and second day’s work or
layer of rubble masonry.
• The curing for masonry should be done for
minimum two weeks.
• The through stone should be of a length which
is at least thrice the depth.
• The joints should be pointed after proper curing
and racking for at least 25mm (1”) depth.

Mortar and Other Bonding Material

Used for Masonry
Mortar is a mixture of sand, water, lime and
cement used in building construction for
holding stones and bricks together. Mortar
is placed in the joints. The selection of mortar
depends on the load on structure, strength
required, resistance desired for weathering
agencies, etc. Mortar is classified as per its
usage. Its different types are lime mortar,
cement mortar, cement lime mortar and
lime cement mortar.
When a portion of cement is replaced
by hydrated lime, it is called ‘cement lime Mortar Joint
mortar’. This mortar spreads more easily Chisel
and faster. Spread with the help of a
trowel, it acts as a smooth material like
plastic. In ‘lime cement mortar’, a part of
lime is removed and replaced by cement.
It makes the mortar stronger, workable
Hammer
and more smooth. This type of mortar gets
settled easily and faster.
• Masonry in cement mortar
• Masonry in lime mortar
• Masonry in mud mortar
Fig.1.28: Dressing the stone with tools

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 Chisel

Measuring Tape

Square

Curing Pipe

Mortar Pan (Ghamela)

Bucket

Tacha

Spirit Level
Line string

Spade
Trowel (Phavada)
(Thapi)

Mallet Plumb Bob

Fig. 1.29: Tools used in stone masonry

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 Thickness of Masonry
• 10 cm thick
• 20 cm thick
• 30 cm thick
• 40 cm thick
• 50 cm thick
• 60 cm thick

Proportion of Mortar
• Masonry in cement or lime mortar 1:8
• Masonry in cement or lime mortar 1:6
• Masonry in cement or lime mortar 1:4
• Masonry in cement or lime mortar 1:2
• 1:8, 1:6, etc., is the volumetric proportion where
1 stands for cement or lime and 8, 6 stand
for sand.

Practical Activity
1. Students may do the practice of dressing the stone with
appropriate tools.
2. Students are requested to construct coursed rubble
masonry as per the drawing given below.

Elevation Section

Plan

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 Check Your Progress
A. Short Answer Questions

1. Differentiate between ashlar masonry and rubble masonry.

2. What is the function of the following materials?
(a) Through stone (b) Corbel
(c) Cornice (d) String course
3. Explain the construction of a wall in coursed rubble
masonry.
4. What type of stone masonry will you use for constructing
the following?
(a) Compound wall (b) Parapet wall
(c) Retaining wall
5. What is the object of preliminary dressing of stone at site?

B. Fill in the blanks

1. Stone masonry is constructed with stones and

_____________.
2. In cramped joint, cramps are used instead of ___________.
3. Butt or squared joint is the most __________ joint and is
extensively used for __________ work.
4. The stones of ____________ sizes and shapes are used in
rubble masonry.
5. Coursed rubble masonry is commonly used in
the _________________ of low height walls of public
buildings, residential buildings, abutment and piers of
ordinary bridges.
6. The curing for masonry should be done for minimum
_____________ weeks.

C. Multiple Choice Questions

1. Stone used in construction work should be _____________.

(a) hard (b) durable
(c) soft (d) tough
2. Mortar is prepared by mixing _____________.
(a) cement (b) sand
(c) water (d) All of the above
3. Bottom surface of a door or a window opening is known
as_______________.
(a) sill (b) corbel
(c) cornice (d) coping
4. Small cracks should be cleaned with _____________.
(a) paper (b) cloth
(c) wire (d) brush

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 5. Butt joint is the most common joint and is extensively
used for_____________.
(a) heavy work (b) small work
(c) ordinary work (d) None of these

C. Long Answer Questions

(a) Describe the tools used in stone masonry construction
with a diagram.
(b) Write a short note on uncoursed rubble masonry.
(c) Write the different types of ashlar masonry. Explain any
one.
(d) How the maintenance of stone masonry construction is
carried out?
(e) Enlist the types of rubble masonry. Explain any one.
(f) List the tools used in masonry work.

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