Building Stones.pdf

Building Stones
Building Construction Material

Definition
• Stones are naturally occurring compact,
solid and massive material that make the
crust of the earth.
• Technically, the stones are called as rocks.
The rocks occur in great variety. The rocks
posses suitable properties often find use in
building stones. It follows that all building
stones are rocks in nature, all rocks may not
be useful as building stones.

Introduction
• Stones have been used in all type of construction
since time immemorial. The pyramids of Egypt, The
eiffel tower, The temple of Jagannathpuri, the Taj
Mahal, the red fort, the great wall of china and
hundreds of historical buildings in each big country are
made of stones. The greatest thing about stone is that
they are natural and do not required to be
manufactured.
• Stone, timber and clay had been the most commonly
construction used material right from the beginning
of the civilization till the advent of Portland cement
and hence concrete in the early nineteenth century.

Classification of Stones
• The building stones are classified in three
ways: Geologically, Chemically and
structurally

A ) Geological Classification:
• This classification is based on mode of
formation of the rock from which building
stones are obtained. Three main group
recognized are:
• I) Igneous Rocks
• II) Sedimentary Rocks
• III) Metamorphic Rocks

Igneous Rocks (Greek word ignis= fire)
• All those rocks of the earth that have been
formed by the natural process of cooling and
crystallization from originally hot and molten
magma are grouped as Igneous Rocks. They are
the most abundant rocks in the crust when
considered depth wise.
• In fact the igneous rocks are further
distinguished by geologists into three sub
classes on the basis of their depth of formation.

(a) The Plutonic Rocks
• These are formed at greater depth below the
surface. They are exposed on the surface by
erosion of the overlying secondary rocks
with passage of time. They are coarsely
crystallized. i.e. the component of crystals can
be easily seen without the help of magnifying
glasses. Granites, Syenites and gabbros are
typically igneous plutonic rocks.

(b) The Volcanic Rocks
• These are formed on the surface of the earth
from lava coming out of numerous
volcanoes that erupt from time to time.
Basalt and trap rocks are very common
examples; the constituents minerals are so
small that they can be seen only after
magnifying under microscope.

(c) The Hypabyssal Rocks.
These are formed at shallow depths, about
2-3 km below the surface from magma that
could not come out as lava. They show
crystal that are partly coarse and partly fine in
size. Rock known as porphyries belong to
this group.

Sedimentary Rocks
• Sedimentary Rocks (sediment=particle)
They are the most widespread rocks
found covering a great part of the surface of
earth. The Sedimentary rock are formed
from any type of preexisting rocks by a
simple process of breakdown into smaller
particles under the influence of natural
agencies like wind, water and ice and
atmospheric gases.

Sedimentary Rocks
• The natural process of rock disintegration are
called weathering and erosion. The sediments
produced by natural agencies are transported by
these very natural agencies to riverbed, lake
basin, seas and oceans where this deposition takes
place for million of years. Gradually, the
particles so deposited are compressed under
their own load into hard massive rocks, called
secondary rocks. Since they are formed of
sediments it is quite appropriate to call them
sedimentary rocks.

Sedimentary Rocks
• Just like igneous rocks, sedimentary rocks
may also be formed in different manners.
These sub group of sedimentary rocks are
• Clastic Rocks.
• Chemically formed Rocks
• Organically formed rocks

Sedimentary Rocks
Clastic Rocks
• These are sedimentary rocks formed by
deposition and consolidation of disintegrated
sediments and fragments from the previous
rocks in suitable river basins, lake and the sea
basins etc. They are most widespread and include
such types as sandstones, hales, breccias and
conglomerates. Sandstones are made mostly of
silica grains fused together or thoroughly
compacted under natural environment. They
form very good type of building stone.

Sedimentary Rocks
Chemically formed Rocks
• Many sedimentary rocks are precipitated from
river, lake and especially from seawater by
evaporation etc. some of the components of previous
rocks are taken in solution during the processes of
weathering and erosion. The water may get saturated
with these compounds with passage of time and
precipitate them. The huge accumulation of these
precipitates and evaporates ultimately may form
rock deposits of considerable importance.
Limestones, Gypsum, anhydrite and rock salts are few
examples of chemically formed sedimentary rocks.
None of them are used as building stones.

Sedimentary Rocks
Organic formed Sedimentary Rocks
• As we know that more than 70 % of the surface of earth
is covered with water in the form of sea and oceans.
Great variety of life exists in these great water bodies. Many
sea animals have their hard parts made up of bones, which
are a mixture of calcium and magnesium carbonates. These
parts accumulate at proper places on the sea floor.
Gradually huge thickness of such deposits get formed and
compacted and consolidates with passage of time. These
are the organically formed sedimentary rocks. The best
example of organically formed sedimentary rock is a
great variety of limestone, which now form the greater
part of many mountains of the earth including
Himalayas. Many massive types of limestone form best
type of building stones.

Organic formed Sedimentary Rocks

Metamorphic Rocks
• (meta= Change; morph= form) These are
originally either igneous or sedimentary rocks.
The process for their change under the
influence of increased temperature, pressure,
and chemical environment is called
metamorphism. When an existing rock gets
subjected to increased temperature or changed
stresses and chemically active fluids it undergoes
a slow but definite change in its original structure
and chemical composition. The new rock so
formed is called metamorphic rock.

Metamorphic Rocks
• To well-known example of metamorphic rock
are marble and slate. Marble is formed in
natural environment by very gradual heating of
sedimentary rocks, limestone, in its natural
environment. The heating may be caused by rise
of magma from below in a limestone area.
Similarly, another sedimentary rock, shale may be
formed combined action of temperature, pressure
& chemically active fluids that it gets changed to
a metamorphic rock slate.

Metamorphic Rocks
• The nature of change of an original rock
depend on following factors:
• (i) The type of agent/s operating (
Temperature, Pressure, chemically active fluid
etc.)
• The duration of operation of the above agent.
• The nature and composition of the original rocks,
Some very common metamorphic rocks are
Marble, Quartzite, Gneiss, Slate and Schist; The
first three rocks are very good building stones in
many cases.

Chemical Classification
• On the basis of dominant chemical composition,
following three main groups of rocks are commonly
recognized:
• I.) Siliceous Rocks
• These rock have SILICA (SiO2) as the predominant
component, that is more than 50 % of the bulk
composition of the rock.
• These include variety of quartzites. Naturally they are
classed among the strongest type of building stones.
Some other rocks like granites, sandstones and gneisses
are also made up of Silica in combined form.

2) Calcareous Rocks.
• In these rocks, the dominant component is a
carbonate ,generally of calcium but often
with magnesium. Most commonly they
belong to sedimentary and metamorphic group
of rocks. Limestone, dolomite and marbles
are entirely carbonate rocks and all form
good building stone.

3) Argillaceous Rocks.
• They are mostly sedimentary rocks having
clay (hydrous alumino silicates of K, Na, Ca,
Mg. etc.) as a dominant constituent. They are
invariably soft and untrustworthy as building
stone and untrustworthy as building stones.
Shales, Slates, and Schists are examples.

Structural Classification
• Broadly speaking, in apparent structures,
the rock (Stones) may either be found in the
form of undifferentiated masses or they
occur in very well defined layers or sheets. A
third category is foliated rocks.

1) The Massive or Unstratified Rocks.
• These rocks occur in huge masses without
showing any layered structure in them.
Igneous and many metamorphic rocks and
some sedimentary rocks may be seen
occurring as big masses. Granite and
Quartzite often occur in massive form.

The Massive or Unstratified Rocks

• 2) The Stratified Rocks.
• Most sedimentary rocks occur in distinct
layers of same and different color and
composition. Their different layers are also
called beds and are separated by planes of
weaknesses called bedding planes

3) Foliated Rocks
• Very often a third group of rock is
distinguished as foliated rocks in which
there is profuse development of well defined
band of different composition. This is seen as
schists and gneisses. The foliated rocks do
not yield building stone of good quality.

Quarrying of Stones
• It is known that stones occur in nature in
the form of natural rock masses forming
hills or walls of valleys. These have to be
broken and extracted from those natural
outcrops for using in the construction. The
process of extraction of suitable stones from
their natural place of occurrence for use in
construction is called quarrying.

Quarrying of Stones
• Quarrying is different than mining used for
extraction of ores for metal in that in mining
we go deep below the surface, the top surface
is left in tact, and the ores are extracted from
under the earth. In quarrying, however, the
process of extraction starts from the
surface.

Selection of Quarrying Site
• Engineers and Contractors have to keep in mind
following factors while deciding about the
location of quarry site
• (i) Availability of Sound Rock.
• A quarry can be opened up where a sound rock
that can yield good quality of building stones
existing in sufficiently larger area. These is
essential because quarrying operation require
quite heavy initial investment in men and
machinery and these have to be economically
viable.

• (ii) Distance of Area of Construction:
• Quarrying is a common operation. The
quarrying site must necessarily be close to a
main road so that stones extracted from it
can be transported to any outside place at
economic rate.

Distance of Area of Construction

(iii) Availability of Water and dumping space
• In quarrying operations, large number of
equipments, men and machines are often required.
Sufficient safe distance from quarrying must be
available. Often lot of water is also required for the
workers and even during cutting operations when
machines are to be used. This must be available
locally. Dumping space is required for storing the
broken stone and also for dumping useless rock
fragments obtained during quarrying. Further,
adequate drainage outlet for removing any
underground or surface waters immediately after
rain must be provided at the quarry.

Availability of Water and dumping
space

Preparatory Steps
• Once a site for quarrying of Stone is decided.
Following predatory steps becomes necessary
for starting operations
• i) Selection of method of Quarrying
• Quarrying can be done manually or with
the help of machines. Mechanized
quarrying is the advanced and preferred
method of the quarry, the nature of the rock
and the commercial demand.

Selection of method of Quarrying

Preparatory Steps
• (ii) Preparation of a layout
• A scheme for operation process or layout of
the quarry has to be prepared after
selecting method of quarrying. This should
include the face of attack, the progression of
attack and various stages in which the block
of rocks are removed.

Preparatory Steps
• (iii) Removal of overburden
• The upper surface of natural bedrock is
quite often covered with some thickness of
soil or weathered rock called overburden.
Such overburden as well as loosely held rock
pieces have to be removed well before the start
of quarrying operations.

Methods of Quarrying
A. Quarrying Without Blasting
• In this methods, skilled persons remove
blocks of rocks from the places of
occurrence. They may use hand tools or even
light channeling machines called channellizers.
No explosive material is used for breaking
the stones.

Methods of Quarrying
• B) Quarrying by blasting This method involves use
of explosives for breaking stones from very hard
rock like quartzite and sandstones, basalts, traps,
and non-ornamental granites. It has been observed
that quarrying of these types of hard rock becomes
very laborious and costly by other methods.
• The basic principle employed in this method is to
explode a small quantity of an explosive at a
calculated depth within the body of the rock.
• The force generated due to explosion is sufficient to
only create cracks and loosen rock block of good size.

Dressing of Stones
• By dressing of stones is meant the process of
giving a proper size, shape and finish to the
roughly broken stone as obtained from
quarry. This is done either manually or
mechanically or in some case using both the
methods.

Dressing of Stones
• Stones as obtained from quarries are very rough and irregular
in shape. Besides, they may be too bulky to be used in
construction, Hence various objectives of dressing are:
• (a) To reduce the size of blocks to easily portable units. This is
often done at the quarry itself because transport of big rock may be
costly.
• (b) To give a proper shape to the stone
• We can use stones in foundation as blocks, in walls as small
units, in floor as slabs and in column as rounded or square
pillars. Each situation requires a proper shape that has to be given
under the process of dressing.
• (c) To obtain an appealing finish Stones always come in rough
and rugged forms. For use in building construction in walls and
exteriors, they have to be given an aesthetic appealing finish. A
stone house has its own distinction, beauty and indivuality in a
concrete jungle.

Dressing of Stones
Method of dressing of stones
• Dressing of stones can be done both manually or
mechanically.
• Manually, Skilled workers can work wonders on suitable
types of stones with chisels, hammers and abrasives. Not
only they can give excellent finish and polish stones but also
may do carving and engraving that can withstand centuries.
• Mechanically, special saw fitted machines can cut slabs and
any other shape from rough rocks. These are called rock
cutters. The grinding and polishing machines are fitted with
wheels or discs with abrasives capable enough to give polish
and fine finish to any desired degree even on the hardest of
stones.

Dressing of Stones
• The Traditional Dressing methods applied in manual dressing are described
below:
• Pitched dressing
• In this method, only the edges of a block are leveled skillfully by use of
hammers. The surface is left in original cut.
• Hammer Dressing
• In this method of dressing edge as well as the face are reduced to even
regular surface. It has pitted appearance on the surface.
• Chisel Dressing
• In this method straight grooves are made with the help of a chisel at all
four edges. The superfluous stone from the centre is removed. Chisel
drafted stones are specially used in plinths and corner of the building.
• Rough Tooling
• The edges are first made square by using chisel and hammer. Then a
series of grooves of variable width are developed over the surface of stone.

Dressing of Stones
• Punched Dressing
• It is done on the stone that have been already
been roughed. A series of parallel ridges are
made on the stone surface using hammer and
chisel. It is also called furrowed finish.
• Closed picked fine tooling
• This is extreme type of dressing in which
almost every type of projecting irregularity is
removed from all four sides of stones. Its
surface is given fine finish and an appealing look.

Dressing of Stones
• Boasted Finish
• It is a very common type of finish in which the
surface of the stone is covered with parallel
marks that may run in a particular direction
on a particular face. A boaster which is actually
a wide-edge chisel is used for the purpose and
hence the same.
• Numerous other types of finishes are given to
stones in the dressing process depending upon
the skill of the worker and fancy of the owner.

Selection of Stones For Construction
• Three factors are generally considered by an engineer while
deciding use of stone in construction jobs:
First
• The type of building and the situation where stone is to
be used such as :
• First
• 1) Residential building or a public building, such as for
school, department office, community centre etc.
• 2) Commercial building like cinema hall, shopping complex
stadium, etc
• 3) a monument building such as templr, mosque, church,
fort etc.

Second:
• The precise location in the building where
the stone shall give a preferential benefit in
terms of cost, appearance, and durability
such as in foundations, superstructures, arches,
columns, beams, plinths, or flooring, sills and
cantilever.

Third
• Cost of construction with stones. This will depend on
factors of availability of stone, in nearby area, their
extraction, transportation and dressing before
putting them in use. Sometimes a desired quantity of
stone may not be available locally. It may have to be
imported from other states or even from other
countries.
• It is only after through analysis of factors as
mentioned above that the engineer will be able to
decide about using stone in the construction at hand.

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

Building Stones.pdf

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