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OCCURRENCE OF GYPSUM
PROPERTIES AND USES
GYPSUM THROUGH THE AGES
Gypsum is a rock like mineral commonly
found in the earth’s crust,
extracted, processed and used by Man in
construction or decoration
in the form of plaster and alabaster.
During the time of
the Pharaohs, Gypsum was used as
mortar in the construction of the
Cheops Pyramid (3000 B.C.).
Chemically it is CaSo4.2H2O i.e.
Calcium Sulphate Dihydrate.
Impurities: MgO, Al2O3, Fe2O3, SiO2,
• Colour- transparent to white
and can be of grey, green ,pink, blue and
red because of impurities
OCCURRENCE OF GYPSUM
A common mineral, with
thick and extensive evaporite
beds in association with
Gypsum is deposited in lake
and sea water.
Hydrothermal anhydrite in
veins is commonly hydrated
to gypsum by groundwater
in near surface exposures.
Often associated with the
minerals halite and sulfur.
Crushing (~25 mm
Cooling and Pulverizing
Marketing in Bags
Gypsum rock when heated to 100-190°C looses ¾ of its water.
CaSO4.2H2O → CaSO4.½H2O + 3/2 H2O
Plaster of Paris
This is low burning process and named as INCOMPLETE
When calcination is carried out at temperatures above
190°C all water is removed.
CaSO4.2H2O → CaSO4 + 2H2O
This is high-burning process & COMPLETE CALCINATION.
Both of these products form gypsum rock by recombining
CaSO4.½H2O + 3/2H2O → CaSO4.2H2O
CaSO4 + 2H2O → CaSO4.2H2O
Calcination process is carried out in two types of kilns.
~ 2.5-3 cm
~ 2-3 m
Obtained by Incomplete Calcination (CaSO4.½H2O)
1. Plaster of Paris : is formed by incomplete calcination at 100-
190°C. No admixtures are found.
2. Hard Wall Plaster
Plaster of Paris + Admixtures (Glue, Sand...)
Obtained by Complete Calcination (CaSO4)
1. Flooring Plaster (CaSO4 with no impurities)
2. Hard Finish Plaster (CaSO4 + Al2(SO4)3)
(CaSO4 + Na2B4O7)
What is Gypsum Board?
Gypsum board, commonly known as
drywall, is the technical product
name used by manufacturers for a
specific board with a gypsum core
and a paper facing.
Gypsum board is the premier
building material for wall,
ceiling, and partition systems in
residential, institutional, and
commercial structures and is
designed to provide a monolithic
surface when joints and fastener
heads are covered with a joint
Making Gypsum Board
•To produce gypsum board, calcined gypsum is mixed with
water and additives to form a slurry which is fed between
continuous layers of paper on a board machine.
•As the board moves down a conveyer line, the calcium sulfate
recrystallizes or rehydrates, reverting to its original rock state.
•The paper becomes chemically
and mechanically bonded to the
•The board is then cut to length
and conveyed through dryers to
remove any free moisture.
•Gypsum manufacturers also rely
increasingly on “synthetic”
gypsum as an effective alternative to natural
PROPERTIES AND USES OF
Plaster of Paris
•Setting time ~5-20 min.
•Used for sculpturing, ornamental work, small repair works.
Hard Wall Plaster
•Setting time ~1 hr
•Compressive strength ~7 MPa
•Admixtures result in increased plasticity & setting time &
•Can be used for plastering walls
•Production of prefabricated structural units
•Masonry bricks & blocks
Flooring, Hard Finish Plaster
•Setting time ~1-16 hrs
•Compressive strength > 7 MPa
•Can be used for producing prefabricated units, masonry
bricks & blocks & flooring & pavement bricks & tiles.
Gypsum often serves as a fire proofing material even though its
strength is destroyed by long continuous heat. It forms a powder
covering the surface which acts as an effective insulator.
Gypsum products tend to disintegrate when exposed to
moisture. Therefore, they should not be used for exterior work &
for moist interiors.
OTHER USES OF GYPSUM
Gypsum can indeed also:
Be added to some bread and dough mixes as a Calcium source
and baking aid.
Be used as a filler and fire retardant in plastic products.
Be used in Portland cement and special cement products for
set and expansion control.
Be a source of Calcium and Sulphate Sulphur for plant growth.
Be used as a modelling material for tooth restorations.
Be an ingredient in many patching compounds.
Be used with glass to fabricate large, lightweight architectural
Be used as a mould material to fabricate custom body parts for
trucks and automobiles.
Be an aid in juice extraction of some fruits and vegetables
The Modern Use of Gypsum in
The modern use of Gypsum as a building material was discovered
in 1888 when the American Augustine Sackett invented a
machine for producing plasterboards (also known as wallboards
and dry walls) composed of several layers of paper with
In Eastern and
there are currently
more than 200 factories
Uses of Gypsum Products in
• Plasterboard is used for partitions and the lining
of walls, ceilings, roofs and floors. The properties
of plasterboard can be modified to meet specific
requirements, such as fire resistance, humidity
resistance, impact resistance, etc.
• Plaster powder, mixed with water, manually or
through the use of silo-supplied spray systems, is
used to create an effective and aesthetically-pleasing
lining for brick and block walls, and for ceilings.
• Gypsum’s adaptability in application lends itself to
moulding and shaping. Since time immemorial, Gypsum
has been used by skilled craftsmen to create decorative
• Gypsum plaster is used for walls and ceilings.
• Gypsum blocks are used for partitions and Gypsum tiles for
Gypsum based self levelling screeds
• Anhydrite or Alpha- Hemihydrates are used in the production
of self levelling floor screeds.
•Gypsum fibreboard is used for partitions and lining of walls,
ceilings, roofs and floors. Gypsum Fibreboard offers good
performance when it comes to impact resistance, sound
insulation and humidity resistance.
Gypsum Products Unique
1) FIRE PROPERTIES
•Due to the natural composition of Gypsum, gypsum plasterboards are inherently
•The chemical formulation of Gypsum is CaSO4.2H2O - Calcium Sulphate
•In nature, Gypsum occurs in the form of
•The presence of water in Gypsum (H2O),
one square meter of plasterboard of 15 mm
thickness contains around 3 litres crystal
•Through the action of fire, the crystal
water evaporates and a protective layer
of Gypsum is formed.
•Behind this layer, the material under fire
attack, remains at constant temperature
around 100oC as long as water is released
from the Gypsum.
• The inclusion of glass fibres in Gypsum boards enhances their fire protection
performance by maintaining the integrity of the board in a fire.
•Gypsum is a powerful fire retardant element in the construction sector due to its
non-combustibility and ability to delay for up to 4 hours - according to the
number of plasterboards in the corresponding system - the progression of fire.
2) ACOUSTIC PROPERTIES
•The Gypsum Industry has a beneficial impact on noise reduction as it produces
special acoustic grade plasterboard which offers greater sound extinction which
can be applied where a particularly high performance is required.
•Drywall systems provide effective sound insulation because they are
designed to provide a physical barrier to sound, incorporate a sound
break and minimise reverberation.
•Between the two sides of the partition there is an air cavity, which interrupts the
flow of sound.
•Because the two sides of the partition
are separate it is harder for impact
sound to pass through.
•These characteristics mean that a typical drywall partition in a house
can be only 75mm thick. A comparable masonry wall would need to be
110mm thick to achieve the same sound performance.
3) THERMAL PROPERTIES
•Lightweight building techniques (plasterboard on framework) can
supply excellent thermal performance since the construction has a
cavity that can be filled with the required amount of insulation.
•The interior plasterboards protect the insulating material and contribute,
together with the vapour barrier, in preventing indoor humidity from
getting in, or being trapped in, the insulation material.
• Gypsum equilibrates humidity and heat peaks
•Gypsum is capable of storing humidity when a room is humid and
automatically releasing this humidity if the indoor air becomes too dry.
•Plasterboards have also a “heat-storing” ability. Small temperature
increases are absorbed and radiated back later when the temperature in
the room decreases.
4) AESTHETICS AND DESIGN
•A richness of forms can be created in plasterboard or stucco.
•For architects, building with gypsum products allows them to unleash their
creativity thus allowing them to answer, even more dramatically, to
the demands of their customer while remaining within an affordable
•In short, Gypsum allows the creation of stunning interiors in any
and all styles, from the Classical to the Modern.
5) EASE OF ISTALLATION
•One of the principal reasons for this rapidly growing
popularity is ease of installation.
•To construct an internal wall, for example, a frame is erected, plasterboard is fitted to it,
joints are filled, and the wall is created.
•The operation is clean, dry and uncomplicated.
•A gypsum finish can also be applied to the surface of the plasterboard in
order to achieve a superior finished appearance.
Gypsum Through the Ages
•As demonstrated by its presence in the Egyptian
pyramids, gypsum has served as a vital piece of many
famous construction projects throughout history.
•Over thousands of years, this important mineral has
demonstrated its versatility and sturdiness and has
become a staple in today’s homes, buildings and
•This section provides an informative look at what gypsum
is, the history of its use and how gypsum board is made.
Centuries of Reliability
Gypsum has been used in construction since the days of ancient Egypt, where it
was used in building the Pyramids. Some of this construction is still visible
over 5,000 years later, a tribute to gypsum’s durability as a building material.
•Alabaster is a form of gypsum used both
in building and as a decorative
•Large deposits of gypsum were discovered
near Paris, and “Plaster of Paris” became
a popular building material.
•Plaster of Paris is raw gypsum that is
chemically altered by heat to remove much
of the water naturally occurring in gypsum.
•French farmers also used natural gypsum
as a soil additive to improve crop yields.
Gypsum Boards in Construction
The use of gypsum boards in construction began in the late 19th century, after
Augustine Sackett patented “Sackett Board,” layers of thin plaster of Paris
placed between wool felt paper.
•Sackett Board was often used as a replacement for wood and as a base for
the application of plaster. In 1893, the exterior of the World’s Columbian
Exposition palace in Chicago was finished with gypsum plaster bound with
•By 1916, Sackett’s product was a ready-to-finish board for use in construction,
similar in concept to today’s modern gypsum board.
The Gypsum Industry Booms
The demands for rapid construction of military housing brought about by
World War I led to a sharp increase in the demand for gypsum board. After a
barracks fire tragically took the lives of several servicemen, gypsum board’s
fire-resistant qualities made it the preferred choice in military housing.
•Because gypsum offered significant advantages over
traditional heavy masonry and concrete, the gypsum industry
focused on expanding its use in commercial construction.
•To meet the demands of high-rise building, the
industry developed gypsum board
shaft wall systems and movable
partitions systems as well as improved
•The tallest buildings in the world at that time—
the John Hancock Tower, at 100 stories,
and the Sears Tower, at 110 stories—
used gypsum board in construction.
The Gypsum Industry Today
Now, with over 97% of new homes using gypsum board, it is clearly the interior
construction material of choice.
As a result of gypsum’s remarkable ability to adapt, to be recast and
reformulated into many different and valuable materials, the industry
continues to innovate while meeting today’s demands for environmental
• THE COMPANIES THAT MARKET GYPSUM PRODUCTS ARE: AEROSTONE,
VANS GYPSUM, SAINT GOBAIN GYPROC, INFINITE IMPEX, ETC.
• GYPSUM IN MARKET IS AVAILABLE IN BOARD FROMS OR SQUARE TILE
• THE AVERAGE GUARANTEE GIVEN TO THESE PRODUCTS IS NEARLY 30 YRS.
TYPE RANGE SIZE IN MM PRICE
GRG TILES REGULAR 595 X 595 X 7 99.62 796.94
MEDIUM 595 X 595 X 15 156.21 937.27
HIGH 595 X 595 X 29 382.38 1147.43
TYPE RANGE SIZE IN MM PRICE INR/
GYP BOARD REGULAR 1830 X 1220 X
HIGH 1830 X 1220 X