Introduction and classification of rocks

Introduction and classification of rocks for building and construction materials... types of rocks and their classifications, and types of stone quarrying.

1. BUILDING MATERIALS
CONSTRUCTION PLANNING

2. Classification of stones :
•Construction planning is a fundamental and challenging 
activity  in  the  management  and  execution  of 
construction projects.
  
•The term rock is commonly defined as a hard mass of   
mineral matter having, as a rule, no definite external 
form.
•The word stone is applied indiscriminately to all classes  
of hard rocks.

3. Description of Classes:
    Rocks are classified as follows:
1.According to geological origin- 
             Igneous, Sedimentary and Metamorphic
2.   According to the physical form-
            Stratified, Unstratified and Foliated.
3.   According to their chemical composition–
            Silicious, Argillaceous and Calcerous.

4. GEOLOGICAL CLASSIFICATION:
IGNEOUS ROCK:
•Igneous  Rock, rock formed when molten  or  partially  molten 
material, called magma, cools and solidifies. The inner layers of 
the earth are at a very high temperature causing the masses of 
silicates to melt. 

5. SEDIMENTARY ROCKS:
•Sedimentary rocks are types of rock that are formed by the 
deposition and subsequent cementation of that material at the 
Earth's surface and within bodies of water.

6. METAMORPHIC ROCKS:
•Metamorphic Rock is a type of rock formed when rocky 
material experiences intense heat and pressure in the crust 
of the earth. This change from one mineral assemblage to 
another is called metamorphism.

7. Physical Classification of Rocks:
Based on the structure, the rocks may be
classified as:
1.Stratified rocks
2. Unstratified rocks

8.     The layering that occurs in most sedimentary rocks and in 
those igneous rocks formed at the Earth’s surface, as from lava 
flows and volcanic fragmental deposits. The layers range from 
several millimeters to many meters in thickness and vary greatly 
in shape
Stratified Rocks:

9. Unstratified:
   These rocks are not stratified. They possess crystalline 
and compact grains. They cannot be split in to thin slab. 
Granite, trap, marble etc. are the examples of this type 
of rocks.

10. Foliated rocks:
     Metamorphic rock is formed when existing rock (whether it is 
sedimentary, igneous, or another metamorphic rock) is changed 
by intense pressure and temperature. Typically, this happens 
deep within the Earth, or near volcanoes. 

11. Stone Quarrying:
•The  word quarry can  also  include  the  underground 
quarrying for stone.
•A quarry is  a  place  from  which dimension 
stone, rock, construction  aggregate, riprap, sand, gravel, 
or slate has been excavated from the ground.
• A quarry is the same thing as an open-pit mine from 
which minerals are extracted.

12. •Quarrying of stone is completely different from mine. 
•Mine belongs to underground operation only whereas 
quarry is carried out on exposed surface of natural 
rocks.
•Stone quarrying is generally done at hilly areas where 
large quantity of stone is available.

14. Site Selection for Quarrying of Stones:
    The quarry should be selected based on some conditions 
as follows.
•The site should be near to human living areas where 
labor and tools are always available, required materials 
also should be available.
•At least one of type transportation facilities (road or 
railway or port or all) should be available.
•Good quality and quantity of stone should be available.

15. •The site should be far from permanent structures like 
bridges,  dams  etc.  because  the  vibrations  due  to 
blasting in the site may cause harm to them.
•Non-living area should be available to dump the 
refuse obtained in quarrying.

16. Methods of Quarrying of Stones
Quarrying can be done by three methods as follows:
1.Hand tools
2.Machine quarrying
3.Blasting

17. Quarrying of Stones using hand tools:
Wedge method:
In these methods, blocks of rocks are broken loose from their
natural outcrops by men using hand tools:
•It is consists digging a few holes at carefully selected places on
the rock. These holes are dug either manually using chisels and
hammers by the skilled workers.
•Or, in major quarrying, these holes may be drilled by special
machines called hammer drills.
•Once the hole is ready, a steel wedge is inserted in between two
steel strips or feathers. This is done with all the holes drilled in a
sequence.

19. •Such firmly inserted wedges are then struck with hammer
almost simultaneously. This process develops cracks along the
lines joining the holes.
•After that, long iron bars are inserted in the holes and cracks,
and then the blocks of the rocks are pushed forward onto the
free face of a quarry.

20. Quarrying of Stones using Machines:
Channeling Method:
•In this method of quarrying involves the use of big machines
called Channelizers which have reciprocating cutting tools and are
power driven.
•When single large blocks of costly stones like marbles and
limestones are required, this method is most suitable.
•The channelizer can cut a groove as deep as 3 m, as wide as 5 cm
and as long as 3 m, or even more.

21. •When a single block is required, grooves of required depth and
length are first cut at the back and sides of the working face of
the quarry.
•Single blocks as big as 10 meters long and 3 meters thick and 1-
3 meters wide can be quarried by this method from soft rocks.

22. Quarrying of Stones by Blasting:
•This method consists of using explosives for breaking stones
from very hard rocks.
•It has been observed that quarrying of granites, basalts, traps,
quartzites, and sandstones by wedging and other methods is
very laborious and costly.
•These hard rocks, however, can be loosened economically and
easily by using explosives.

23. •The basic principle of this method is to explode a small quantity
of an explosive material at a calculated depth within the rocks.

24. •The force generated due to this explosion is sufficient
only to create cracks and loosen blocks of good size.
• Blasting for quarrying for stones may be quite
different from blasting for road clearance.
•In the latter case, the size of the broken stone is of not
much consequence.

25. •Quarrying by blasting, therefore, requires very
experienced persons thoroughly acquainted with
blasting explosives on the one hand and strength
qualities of rocks on the other hand.

26. Precautions in blasting:
1.The blasting should not be carried out in late evening (or) early
morning.
2.The danger zone should be marked with red flag.
3.Explosive should be stored and handled carefully.
4.First aid should be made available.
5.Detonators and explosives should not be carried together
A detonator, frequently a blasting cap, is a device used
to trigger an explosive device.

27. Dressing of Stones:
•The Dressing of stone is defined as “The process of giving a
proper size, shape and finish to the roughly broken stones as
obtained from the quarry.”
•This process is done manually or mechanically. A dressed stone is
fit for use in a particular situation in a building.

28. •Stones obtained from the quarries are very rough and irregular in
shape and quite bulky in size and weight.
Various objectives of dressing are below:
(a) To reduce the size of the big blocks of stones so that they are
converted to easily lift-able pieces. This reduction in size is
generally carried out at the quarry itself because that saves a lot of
transportation cost.

29. b) To give a proper shape to the stone. It is known that stones
can be used at different places in the building, e.g. in
foundations, in walls, in arches or for flooring, each situation
will require a proper shape.
(c) To obtain an appealing finish. In a residential building,
stones are used not only because of their extra strength,
hardness, and durability but also because of their aesthetic
value.
Stone surfaces can be made very decorative and of appealing
appearance which will last for a considerable time. A stone
house has its distinct individuality in a city of concrete
structures.

30. Methods / Types of Dressing of Stones:
•As said earlier, dressing of stone can be done both manually as
well as mechanically.
•Manually, skilled stone-smiths can work wonders on the suitable
type of stones with chisels and hammers and abrasives.
•Mechanically, machines can cut the stone to any desired size and
shape. Their surfaces can be made extra smooth by polishing
through machines.

31. Stone Brick
Light in weight
Cheap in cost
Easy to handle
Transportation

Strength and durability

32. COMPOSITION OF BRICK EARTH:
• Bricks are defined as artificially moulded clay blocks, with
mass of natural clay with uniform size and shape.
•The bricks are suitably dried and burnt to attain strength,
durability etc. to made them useful for construction works.
•As per IS: 2117-1375, the clay or mixture of clay selected
should preferably confirm to the following chemical
composition for good results.

33. Requirements of good brick earth:
•It should be homogenous and contain desired proportions of
ingredients(clay, silt, silica etc.)
•It should be free from pebbles etc.
•It should also free from lumps of lime or nodulus of kankar.
•It must be free from alkaline salts and chlorides.
•It should not contain vegetable and organic matters.

34. Ingrediants used in the preparation of bricks:
1.Silica
2.Alumina
3.Lime
4.Iron oxide
5.Magnesia

35. S.No Ingredient Proportion Functions
1Clay(Alumina)20 to 30% by
weight
It absorbs water and
renders clay plastic.
Excess alumina produces
cracks on drying.
2Silt 20 to 35% by
weight
It supports the sharp edges
of bricks and helps to
remain intact during
drying and burning of
bricks.

36. S.No Ingredient Proportion Functions
3 Silica (sand) 35 to 50% It retains its shape and imparts
durability and prevents cracking
and warping. Excess of silica
makes the bricks brittle and weak
on burning.
4 Other Ingredients1 to 2% by
weight
a) Lime (CaCo3) It prevents shrinkage of on drying
and makes the bricks hard. Excess
lime caused bricks to melt and
hence its shape will lost
b) Ferric oxide(FeO) It gives good red colour, strength
and durability.

37. S.No Ingredient Proportion Functions
c) Maganese (Mn) Excess presence of
manganese marked
the bricks darker.
d) Sodium potash etc Little excess of
these ingradients
decolours the brick.

38. MANUFACTURE OF BRICKS:
The process of manufacturing of bricks:
1.Preparation of brick earth:
a) Unsoiling:
b) Digging

39. C)Cleaning:
f) Tampering:

40. 2) MOULDING OF BRICKS:
Giving the required shape to the prepared brick earth is known as
moulding of bricks. There are two different ways of moulding.
a)Hand moulding:
i) Ground moulding:
• This method is adopted when a large and level area of land is
available for the purpose.
• The area of land on which moulding is to be done is levelled,
plastered smooth and sprinkled over with sand.

41. •To prevent the moulded bricks from sticking to the moulds either
sand is sprinkled on the inner sides of the mould or the mould is
dipped in water each time before moulding is done.
• When sand is used to prevent the sticking of earth to moulds the
moulded bricks are known as sand moulding.

43. ii) Table moulding:
•In it the moulder carries out the moulding of brick on a table.
•He does so while standing by the side of the table. He moulds
bricks on boards known as stock boards.
•Stock boards are of the same size as the moulds and have a
projection for the frog.
• Sand is sprinkled inside the mould and on the stock board. The
mould is placed to fit the stock board and then filled with earth.
•Sufficient quantity of earth is dashed into the mould pressed hard
and the surplus earth is removed with a strike or a thin wire.

45. b)Machine moulding:
The bricks required are in large quantity, then machine molding
is economical and also saves more time. Here also we are having
two types of machines,
i) Plastic clay machines
•This machines contain an opening in rectangular shape and when
we place the tempered clay in to this machine it will come out
through this opening.
•Now, the rectangular strips coming out the opening are cut by
wires to get required thickness of brick.
• So, these are also called wire cut bricks. Now these raw bricks
are ready for the drying process.

47. ii) Dry press machines:
• Dry clay machines are more time saving machines.
•We can put the blended clay into these machines directly without
tempering.
•Means tempering is also done in this machine by adding some
water.
•When the required stiffness is obtained the clay is placed in mold
and pressed hard and well-shaped bricks are delivered.
•These are called pressed bricks and these do not require drying
they may directly sent to burning process.

48. 3) Drying of bricks:
a)Natural Drying:
•After molding process the bricks contain some amount of
moisture in it. So, drying is to be done otherwise they may
cracked while burning. The drying of raw bricks is done by
natural process.
•The bricks are laid in stacks. A stack consists 8 to 10 stairs.
The bricks in these stacks should be arranged in such a way
that circulation of air in between the bricks is free.
•The period of drying may be 3 to 10 days. It also depends upon
the weather conditions.

49. •The drying yards are also prepared on higher level than the normal
ground for the prevention of bricks from rain water.

50. b) Artificial drier:
•The temperature is usually less than 120’c and the process of
drtying of bricks about 1 to 3 days depending upon temperature
maintained in drier.

51. BURNING OF BRICKS:
The functions of burning of bricks:
1.It imparts hardness and strenght to bricks.
2.It makes dense and durable to bricks.
Note:
1.The bricks are to be burnt properly to achieve strength and
durability.
2.If the bricks are over burnt, they will be brittle and hence
break easily.
3.If the bricks are un burnt, they will be soft and hence can not
carry loads.

52. Clamp burning:
A clamp is a stock of raw bricks protected temperarly
around the sides and top to minimise the loss of heat and
arranged so that it will burn.
Procedure:
•These spaces around each brick are finger width, that is, 2 to 2.5
cm wide.
• This is designed to facilitate the passage of air under the brick
clamp to allow for the even combustion of the fuel.
•Bricks are "set" (loaded onto the base) up to 40 layers high.

53. •The bricks are placed on top of each other for the first 8 to 12
layers, above which each layer is inset by 2 to 3 cm, so that the
clamp tapers towards the top.
•The tapering produces greater clamp stability, which is important
as the whole structure will move with the expansion and
contraction of the bricks during firing.

55. Advantages:
•By burning and cooling of bricks produced are tough and strong.
•It is cheap and economical.
•No, skilled labour and supervision are required.
•The clamp is not liable to injury from high wind or rain.
Disadvantages:
•Its is very slow process and it is not suited for large quantity.
•It is not possible to regulate fire in clamps.
•The quality of bricks is not uniform. The bricks near the bottom
are over burnt and those rear sides are top and unburnt.

56. Kiln’s burning:
a)Intermittent kilns:
•The structure of the kiln is permanent nature, but the process is
doscontinuous.
•After loading the kiln, it is burnt, cooled and unloaded.
•Thus there is wastage of fuel in these kilns as the side walls and
the floor get cooled by the time the kiln is reloaded.

57. b) Continuous kilns:
• In the continuous kilns, while the bricks is one set of chambers
are being fired, the bricks is the next set of chambers are dried
out are preheated, the bricks in the other set of chambers being
loaded and in the last being cooled.