The stones which are suitable for the
construction of the structures such as
retaining walls, abutments, dams,
barrages, roads etc are known as
building stones. Building stones should
possess enough strength and durability.
Stones have been considered as one of
the popular building material from the
olden days due to their availability in
abundance from the natural rocks.
COMMON USES OF BUILDING STONE:
It is used in foundations of buildings,
It is used in construction of dams, barrages, etc,
In its crushed (powdered form) it is used as artificial
It is used as raw material for manufacturing of cement,
In its broken form it is used as material for construction
of road and railway tracks,
It is used as decorative material in buildings,
It is also used as parts of buildings such as lintels and
It is also used as thin slabs for building roofing,
It is also used for ornamental works in buildings,
In its broken form it is in the manufacturing of concrete,
GOOD BUILDING STONES:
There are so many
characteristics of good building
stones, but some important
characteristics are given below.
Hardness denotes several qualities of
stones such as resistance to cutting and
resistance to abrasion ( rub with each
other). Specially stones are used in case of
roads and railway tracks. To check the
hardness of stones various tests are
conducted in the laboratories. The more
important tests to check the hardness is
Loss Angles Abrasion test. It depends upon
the nature of its constituent minerals.
Durability is the power of stone to resist
atmospheric and other external effects.
It depends upon:
Resistance to weathering effects,
Place where it is used
Stone which contain silicates will be durable
than those stone which contain calcareous
(3) Porosity and Absorption :
Stone can hold water in two ways
Either through porosity or absorption
For building purposes, the better stones are those
which are less porous because they will absorb
less moisture. Porous stones damaged easily.
Gases and acids in rain water dissolve some
constituents of stone and cause the stone decay.
In cold countries water freezes and expands and
thus disintegrates the stones.
When exposed to fire stone should be reliable (good
This is an important characteristic of stone. It
depends upon the type of structure of stone in which
we shall use.
E.g. we shall use heavy stones in the construction of
the dams, bridges, etc.
It is power of stone to sustain pressure or resistance
to crushing force.
Average crushing strength of stone is 3 tons per
Appearance and color:
Highly colorful stones are preferred
for architectural purpose but those
are soft and thus less durable.
Therefore, lighter stones are
preferred than to darker ones.
Crystalline structures are more
durable than non-crystalline structure
A good building stone should have good
seasoning qualities. All the stones contain some
moisture which is known as quarry sap stones.
The period 3-6 months are enough for
A good building stone should be fire resistant.
Some stones such as basalt and trap resist fire
very well but some varieties of igneous and
metamorphic stones are very weak against fire.
EXAMINATION AND TESTING OF
It is very important to examine the stone
before its selection for any particular
type of engineering structure. For this
purpose various types of tests are to be
conducted to find out the suitability of
stone for engineering structure. There
are so many tests but some important
among them are as follows.
(1) Crushing test:
For this test 04 cubic cm finely dressed
different samples of stones are used.
Their type is made flat and horizontal and
covered with plaster of Paris. They are
tested in a compression testing machine.
The load must be applied axially and the
changes in the blocks at the
corresponding load are recorded. The
blocks or samples which bear more loads
are to be selected.
(2) Crystallization or weathering test :
For this test 04 cubic cm different samples
of stones are first weighed and then
immersed in a 14 % solution of sodium
sulphate (NA2SO4) at room temperature for
two hours and dried at 1000C . They are
again weighed. This process of weighing,
immersing in salt solution, drying and reweighing is repeated for 10 to 15 times. A
stone which is not much affected by salt
solution is supposed to have very good
(3) Porosity and Absorption test :
To ascertain the relative qualities of
different stones, they are immersed in
water for 24 hours and the amount of
water absorbed by each specimen is
noted. Greater absorption of water by
the stone means that it is porous and
can not resist weathering forces well.
The test specimen which absorbs the
smallest amount of water is the best.
(4) Attrition test:
This is the test to check the wear and tear
of stone. To conduct this test different
angular pieces of stones are weighed and
charged into a cylindrical drum along with
the iron blocks provided. The drum is then
rotated at the rate of 30 to 33 rmp. About
100 to 150 revolutions are made and the %
age of wear is noted. The machine used
may be Devals attrition machine. The stone
which ears less is considered to be the
(5) Acid test:
This is the best test to find out the action of
acids on the stone. For this test about 50 to
100 grams sample of stone is immersed in a
solution of 1 % HCl or H2SO4 for about a
week. The sample being agitated (pressed,
disturbed) at intervals. If the edges of stone
are retained and there is no deposition of
any loose particles on the surface, it
indicates that the stone is good other wise
weak and bad.
(6) Smith’s test:
This test is carried out to find out whether the
specimens possess crystalline structure.
Small stone chips are kept for about half an
hour in a glass of water filled to one third. The
glass containing the specimens and water is
moved quickly by giving it a circular motion
with the hand. If the specimen gives out
earthy matter and water gets milky
appearance, it shows that the stone particles
are not properly cemented together.
(7) Hardness test:
This test is conducted to find out the
resistance of stone to abrasion. The
sample piece of stone is cleaned and
rubbed by piece of rubbing
material/paper. The rubbed face of the
stone is examined through a microscope.
If marks of rubbing are visible, it shows
that the stone is soft and it can not be
used for roads, pavements, etc.
(8) Fire test:
For very important buildings, fire
resistance of stone is also examined. For
this test a small hut or a wall panel of
stone is built. One side of it is subjected
to 9500C and the behaviour of the stone
under fire is studied. If the cracks
developed are deep. Then it should not
be used for important buildings.
(9) Microscopic test:
This is a geological test in which a thin slice of
the sample is examined through the
microscopic to determine the following
physical properties of stone.
The texture of the stone.
The nature of the building materials/stones.
The size, shape and nature of the individual
grains or crystals.
The kind and nature of the mineral present.
The presence of pores, if any.
DETERIORATION OF STONES:
Deterioration of stone is the process of their breaking
or their decay. Atmospheric agencies such as:
rain,temperature,wind,frost, and living organisms, etc
are responsible for their deterioration and these
agencies bring about physical and chemical changes in
the stones and disintegrate them. So, the stones which
can resist the effect of all these agencies are said to be
durable. Some preservative materials which are used
to preserve the stones from deterioration are:
coal tar, linseed oil, barium hydrate solution, alum soap
solution (mixture of alum and soft soap).
By applying some of above preservative materials,
stones can be preserved from the decaying.
CLASSIFICATION OF ROCKS (STONES) OR
VARIETIES OF STONES:
There are three main classes of rocks.
(1) CHEMICAL CLASSIFICATION:
Chemically stones are stones are classified into
(i) Argillaceous Rocks:
Argillaceous or clay stones are those stones which
contain (alumina Al2O3) (clay) as principal
constituent. These stones are less durable stones.
All clay stones belong to this group.
The examples of argillaceous rocks are Slate,
(ii) Silicious Rocks:
The stones which contain (Silica SiO2) as principal
constituent are called silicious rocks. These stones
are durable stones.
The examples of silicious rocks are granite, Quartzite
and Sand stone etc.
• (ii) Calcareous Rocks:
• The stones which contain
calcareous material (CaCO3) as
principal constituent are called
calcareous rocks. They also
contain some proportion of
siliceous and clay matter.
• The examples of calcareous rocks
are marble stone and lime stone,
(2) PHYSICAL CLASSIFICATION:
Physically rocks are classified as:
(i) Stratified Rocks:
The rocks which are split into thin slabs or
layers easily are called stratified rocks. All
sedimentary rocks are essentially stratified
and metamorphic rocks may be either
stratified or unstartified depending upon its
The examples of stratified rocks are Slate,
Sand stone and Lime stone.
• (ii) Unstratified Rocks:
• These rocks do not show sign of
stratification and can not be easily split
into thin slabs or layers are called
unstratified rocks. All igneous rocks are
essentially unstratified and metamorphic
rocks may be either stratified or
• The examples of unstratified rocks are
Granite, Basalt and Lime Trap.
• (3) GEOLOGICAL CLASSIFICATION:
• Geologically stones are stones are classified into
• (i) Igneous or Primary Rocks:
• These are primary rocks which are formed from
molten magma. They represent different
structural features depending upon the condition
of solidification and composition. Generally
igneous rocks are strong and durable.
• These are also called unsratified or eruptive
• The examples of igneous rocks are granite,
basalt, trap, etc.
(ii) Sedimentary or Secondary Rocks:
• These are secondary rocks and are formed by the
denudation and deposition of previously existing rocks
due to weathering actions. Water (rain) is the most
powerful and principal weathering agent. The other
destructive agents are frost, winds and chemical actions.
The destructive agents break up the surface of earth
which gets further broken up when carried down by rains
and rivers. When the velocity of water in the rivers those
broken particles are deposited in the river bed and thus
sedimentary rocks are formed.
• These are also called aqueous and stratified rocks.
• The rocks which are formed by gradual deposition are
called Sedimentary Rocks.
• Examples: Lime stone, sand stone, etc.
• (iii) Metamorphic or Tertiary Rocks:
• Rocks which are formed due to
metamorphic action of pressure or internal
heat or by both (or) alteration of original
structure due to heat and excessive
pressure) are called Metamorphic Rocks.
• Examples: Marble etc.
• QUARRYINFG OF STONES:
• Stones are extracted from natural rocks in
different sizes. The various methods which
are involved in the extraction of stones
from rock beds are collectively termed as
“Quarrying of Stones”.
• Open part of the natural rock from which
useful material is obtained is known as
• For this purpose particular rock is
inspected (checked) for particular work
and then quarrying operations are to be
• Methods of quarrying:
• It is depending upon the rock and purpose
for which it is to be used.
• Commonly two methods are used for
• (1) Quarrying by digging
• (2) Quarrying by blasting
• (1) Quarrying by digging:
• This is done by three methods.
• (a) By driving steel wedges into
• Fissures, cracks, planes of cleavages are
all weak points in the rock and by taking
the advantage of these weak points, steel
wedges are driven in these natural
fissures or cracks, so that rock splits
• (b) By drilling artificial line of holes:
• Some times line of holes (in rows) is
drilled with the help of chisel and hammer.
Thus, the solidity of rock mark is divided
into small portions and artificial fissures
are made. Steel wedges are driven in
these artificially made fissures. Then all
the wedges are hammered simultaneously
and consequently the rock cracks along
the face of holes.
(c) By swelling hard wooden pegs:
•Some times hard wooden pegs are driven
in either natural or artificially made fissures
and are kept soaked with water. And in this
way rock is splitted.
(d) Quarrying by blasting:
When the rock is very hard and unfissured
then quarrying is done by blasting. Blasting is
the process of loosening the hard and closely
packed material with the help of explosive
materials. Various explosives which are used
for blasting purposes are:
•Gun powder or black powder
But mostly two explosives are used which
are gun powder and dynamite. Where gun
powder is the mixture of potassium nitrate,
charcoal and sulphur and dynamite is the
mixture of nitroglycerine.
There are four main operations are involved
•Boring hole in the rock
•Charging with the explosives
DRESSING OF STONES:
Dressing of stones is a process in which
their surfaces are prepared to a form, fit to be used
for any constructional purpose. Dressing is
according to the type of work and demand.
Purpose of Dressing:
•To give them good looking.
•To provide horizontal and vertical joints in the
•To make them fit, to be used for particular
•Generally to give them neat/good appearance.
• Methods of Dressing
Rough dressing Fair dressing
Dressing at quarry site
• Dressing at construction site
,Hammering , Self faced, quarry
Chisel Tooled, Fluted , Pointed
Rock faced dressing
(1) ROUGH DRESSING OR DRESSING AT
There are three main methods of
rough dressing, which are a sunder:
In scabbling only irregular angels are
taken off with a scabbling hammer and
therefore that dressing is called scabbling.
(ii) Hammer Dressing:
In hammer dressing stones are roughly
dressed at a site with the help of quarry
hammer and therefore work is called
• (iii) Self faced, quarry faced (OR) Rock
In this type of dressing, stone are only
splitted into either as face stones or as
corner stones and nothing special is done.
• (2) FAIR DRESSING OR DRESSING AT
There are four main methods of Fair
dressing, which are a sunder:
• (i) Chiseled Dressing:
About one inch width on all the four sides of
the exposed surfaces of the stones is
chiseled to give them a better
appearance. This work is done with the
help of chisel made of cast iron.
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