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					Plaster Of Paris (POP)

      Ankita Sharma
             &
     Gourav Sharma
     B.Tech (4th sem)
          (CET)
HISTORY

   In 1666 due to the accident “Big London Fire”
    the King of France ordered to cover the
    wooden house by POP because in
    1Kg,200Gm water evaporate, when contact
    with fire.
   In 17th century, Paris was known as capital of
    Plaster.
WHAT IS POP?


   Plaster of Paris is a type of building material
    based on calcium sulphate hemihydrate,
    nominally CaSO4·1/2H2O. It is created by
    heating gypsum to about 150 °C.

   2 CaSO4·2H2O → 2 CaSO4·1/2H2O + 3 H2O
    (released as steam).
   Plaster of Paris is a type of plaster which
    can be used in art, architecture,
    fireproofing, and medical applications.
    When people think of “plaster,” they are
    often thinking specifically of plaster of
    Paris.
     POP IS MADE OF

   It is made from a soft rock called
    gypsum.
   Chemical formula of gypsum:
    2CaSO4·2H2O
   It is also made from selenite.
   Chemical formula of selenite:
    CaSO4·2H2O
      GYPSUM - Alabaster
      CaSO4
   Gypsum has several
    variety names
   Class: Sulfates
   Cleavage: good in
    one direction and
    distinct in two
    others
   Hardness: 2
   Specific Gravity:
    2.3+
   Streak: white
        SELENITE
        CaSO4·2H2O
   Colors: White to
    colorless, and transparent
    to translucent.
   Luster: Vitreous to
    Pearly, especially on
    cleavage surface.
   Crystal
    System: Monoclinic, 2/m
   Class: Sulphates.
   Hardness: 2.
   Specific Gravity: 2.3+
   Streak: White.
    MANUFACTURING OF
    POP
   Crushing sintering grinding packing
   Gypsum is crushed in disintegrator which
    is type of hummer crusher.
   Crushed gypsum is sintered in drum at
    150*C for 3 to 4 hrs by solid fuel.
   Wood is used as solid fuel.
   Sintered gypsum is grinded in polarizer
    which is type of hammer mill grinder.
Hammer Crusher Machines
FIRING IN POP BY FOLLOWING
FUELS
Wood:-Ash deposition on wood.
      Preheating of secondary air.
      Preheating of wood section to be
      burn.
Liquid & gas:- one burner of required
       capacity
      numbers burners of low capacity.
PHYSICAL REQUIREMENT
CHARACTERSTICS            REQUIREMENT

Material remains on       nil
150micron sieve
Material remains on       7%
75micron sieve
Temperature rise when     12*C
adding water
Setting time              15-30 min
MOR                       4MPa
D.C.S                     7MPa
Normal consistency (%by   60-80
mass)
CHEMICAL REQUIRMENT

CHARACTERISTICS           REQUIRMENT

Free moisture (%by mass) 2.0

Carbonates (CaSO3) (%     3.0
by mass)
Matter soluble in HCl (%by 7.03
mass)
CaSO4 (%by mass)          85.0
     WATER IMMERSION


   POP casts deformed permanently after
    water immersion
NORMAL CONSISTENCY OF
MATERIAL
   POP is found to have a greater variability
    in strength than synthetic material
   Normal consistency of POP is required
    amount of water which gives the standard
    fluidity to the POP paste.
   Ideal normal consistency is 18.3 parts of
    water in 100 parts of POP powder
   Practically normal consistency is 60-80
    parts of water in 100 parts of POP powder
FACTORS AFFECTING STRENTH
OF POP

   Water content

   Setting time

   Temperature of soaking water
In architecture


                     Plaster may also be
                      used to create
                      complex detailing for
                      use in room interiors
rffa
In home
             Plaster may also be
              used as low cost wall
              putty
    In art

   Plaster may also be
    used to make statues
    and paintings
          In medicine

   Plaster is widely
    used as a support
    for broken bones
In medicine
In medicine

   Plaster is also used within radiotherapy when
    making immobilization casts for patients

   In dentistry, plaster is used for mounting
    casts or models of oral tissues

   Plaster is also used to invest or flask wax
    dentures
OTHER USES

   Plaster may also be used in granite and
    marble cutting.

   It may also be used in artificial sets.

   It may also be used in fireproofing.
Safety issues

    The chemical reaction that occurs when
    plaster is mixed with water is exothermic in
    nature and can therefore cause severe burns
    for this reason only thin layers of plaster
    should be used, with time to cool between
    layers, or strips of cloth in plaster laid-up in
    the method used by the medical field
        COST ANALYSIS
       (PER TONE)
ITEMS           COST (in Rs\TONE-.)
Raw Material    850
Fuel            700
Power supply    110
Labor           200
Wastage         170
Maintenance     100
Packing         240
Market Rate     2500
      Thank You

For your kind Attention

				
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posted:5/14/2010
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