Building Stones

1. Module 2: BUILDING STONES
• Properties of Rock
• Requirement of good building stone
• Building Stones of India
• Groundwater : Sources, water table, zones of ground water
• Porosity and Permeability

2. BUILDING STONES
• The building stones are products of rocks that are
used in constructing buildings, dams, bridges, etc.
• The rock material used for construction includes:
(i) building stones-in the form of masonry blocks,
(ii) rubbles –in the form of small irregular
fragments,
(iii) crushed stones o make concrete, and
(iv) lime stones-to make lime and cement

3. Properties of Building Stones
• In order to select the rock material for construction, the
properties that are commonly examined are:
(i) Mineral Composition
(ii) Texture
(ii)Structure
(iv) Porosity
(v) Permeability
(vi) Durability
(vii) Strength of Rock
(viii) Heat Resistance

4. Mineral Composition
• The rocks are aggregates of minerals. If the
mineral constituents of a rock are hard, free
from cleavage and resistant to weathering, it is
likely to be strong and durable.
• The rocks which are rich in weak minerals,
such as micas, chlorite, talc, felspars and clay
minerals are not durable.

5. Texture
• Fine grained rocks are generally more dense
and stronger than
coarse grained rocks. It is for this reason that
the basalts and dolerites are
widely used as road material

6. Structure
• Many rocks contain structures like stratification,
lamination, foliation and
cleavage.
• Such rocks bear greater loads if they
are placed in the construction parallel to the
planes of weakness.
• Further, since laminated or banded rocks may
scale badly due to weathering, it will not be wise
to place them in the civil engineering works with
the cleavage or bedding planes vertical.

7. Porosity
• The porosity of a rock is the ratio of the volume occupied
by pores to the total volume of the rock sample.
• It is generally expressed in percentage of the volume of the
sample.
• If W1 is the weight of the dry rock sample, W2is the weight
of the sample when it is made saturated with water
and V is its total volume, the porosity P can be determined
as follows (FORMULA)
• A less porous rock is generally more durable and strong and
therefore it is preferred for construction purposes

8. Permeability
• Permeability is the capacity of a rock to transmit water.
It indicates the case with which the water can percolate
through the opening of the rocks.
• The permeability of rocks is particularly important in a
number of engineering problems such as those
connected with dams, reservoirs water supply, sanitary
engineering and other structures.
• The permeable rocks are considered harmful because
they cause seepage of water which may lead to the
destruction of the structure

9. Durability
• The durability of a stone is its capacity to retain its own size,
strength and appearance throughout a long period.
• Some rocks do not resist weathering, decay and lose strength
early.
• The durability of a rock is directly related to its mineral
composition and texture
• In cold countries the frost action plays an important part in
disintegrating rocks. The water which enters into the openings
of a rock, freezes during the night. On freezing it induces
tensile stresses due to which cracks develop
in the rocks.

10. Strength of Rock
• The strength of a rock is determined by knowing its crushing strength,
shearing strength and resistance to abrasion.
• The "crushing strength" is the resistance offered by a stone to pressure.
• The resistance offered by a stone to shear stresses which tend to move one
part of a specimen with respect to the other, is called "shearing strength".
• The stones which are to be put in the foundation of civil engineering
structures, must have high crushing and shearing strength.
• For making road metal the rocks having high crushing strength are selected
• The resistance of a stone to scratching or rubbing action is called its
"resistance to abrasion".
• The stone used for paving and flooring purposes must have high resistance
to abrasion

11. Heat Resistance
• When rocks are heated to a high temperature
and then would, they may get damaged. This is
particularly the case if they are rich in minerals
like calcite and feldspar
• The rocks in the order of decreasing resistance
to damage by fire are sandstones, granites,
lime stones, gneiss and marble

12. Rocks and Building Stones
1. Granites
• Granites are used for construction
purposes on account of their high crushing
strength, low porosity and pleasing pink or
grey colours.
• They are capable of taking good polish.
Granites are commonly used for massive
masonries, and for architectural work.

13. 2. Basalts and Dolerites.
• The basalts and dolerite are fine grained igneous
rocks of basic composition.
• These rocks serve as excellent road metal
because of their high crushing strength.
• Although the basalts are easily workable and
durable stones, they are not used commonly as
building stone due to their dull and unpleasant
colour.
• The basalts which are commonly known as the
Deccan
traps occupy a wide region of western and central
India.

14. 3. Sandstones and Quartzites.
• Well cemented sandstones generally have all the
characters of a good building stone.
• In India the Upper Vindhyan sandstones are
widely used for building work.
• They are used both for masonry work and as
flagstones. Many historical buildings of Delhi,
Agra and Rajasthan are made up of the Vindhyan
sandstone.
• Quartzites do not for good building stone because
their extremely hard nature renders their working
difficult

15. 4. Lime stones and Marbles.
• Because of their homogeneous texture, easy
workability and pleasing colours, limestones
and marbles form good building stones.
• The limestones are not only used as building
stones, they are also used for making lime and
cement

16. 5. Slate
• The slate is a metamorphic work which can be
broken easily into thin smooth slabs.
• It is used chiefly for roofing and paving in
buildings.