Cement is a finely ground mineral powder, primarily made from limestone and clay, that acts as a binding agent when mixed with water, sand, and gravel to create concrete. The manufacturing process involves heating raw materials in a kiln to produce clinker, which is then ground with gypsum to form ordinary Portland cement. Various types of blended cements incorporate supplementary materials like fly ash or slag to enhance properties such as strength, setting time, and heat resistance.

1. CEMENT
Cement is a finely ground, usually grey
colored mineral powder. When mixed with
water, cement acts as a glue to bind
together the sand, gravel and crushed stone
to form concrete, the most widely used
construction material in the world

2. • Cement is typically made from limestone and clay or
shale. These raw materials are extracted from the
quarry crushed to a very fine powder and then
blended in the correct proportions.
• This blended raw material is called the 'raw feed' or
'kiln feed' and is heated in a rotary kiln where it
reaches a temperature of about 14000 C to 15000 C.
• The raw feed enters the kiln at the cool end and
gradually passes down to the hot end, then falls out
of the kiln and cools down.

3. • The material formed in the kiln is described as
'clinker' and is typically composed of rounded
nodules between 1mm and 25mm across.
• After cooling, the clinker may be stored
temporarily in a clinker store, or it may pass
directly to the cement mill.
• The cement mill grinds the clinker to a fine
powder. A small amount of gypsum - a form of
calcium sulfate - is normally ground up with
the clinker. The gypsum controls the setting
properties of the cement when water is
added.

5. • The most common raw rock types used in
cement production are
- Limestone (supplies the bulk of the lime)
- Clay, marl or shale (supplies the bulk of the
silica, alumina and ferric oxide)
- Other supplementary materials such as sand,
pulverized fuel ash (PFA), or ironstone to
achieve the desired bulk composition

6. Cement is made by heating limestone (calcium
carbonate) with small quantities of other materials
(such as clay) to 1450 °C in a kiln, in a process
known as CALCINATION, whereby a molecule of
carbon dioxide is liberated from the calcium
carbonate to form calcium oxide, or quicklime,
which is then blended with the other materials
that have been included in the mix. The resulting
hard substance, called 'clinker', is then ground
with a small amount of gypsum into a powder to
make 'Ordinary Portland Cement', the most
commonly used type of cement (often referred to
as OPC).

8. The approximate composition of cement is
• Calcium oxide (CaO) = 50 - 60%
• Silica (SiO2) = 20 - 25%
• Alumina (Al2O3) =5 - 10%
• Magnesium oxide (MgO) = 2 - 3%
• Ferric oxide (Fe2O3) = 1 - 2%
• Sulphur trioxide (SO2) = 1 - 2%

10. • Tricalcium Silicate - sets quickly and develops
considerable strength in a few days.
• Dicalcium Silicate - sets slowly and becomes
strong after a month or so.
• Tricalcium Aluminate - sets instantaneously in
the presence of water. Cement's internal
strength is mainly because of this.
• Tetracalcium Aluminoferrite sets rapidly but
not so fast as tricalcium aluminate

11. Four Principle minerals in OPC are designated as
under
C3 A – 4 to 14%
C3 AF – 10 to 18%
C3 S – 45 to 65%
C2 S – 15 to 35%

12. • On hydration silicates and aluminates of
calcium get converted to their respective
hydrated colloidal gels.
• At the same time, hydrolysis precipitates
calcium hydroxide and aluminium hydroxide.
• This calcium hydroxide binds calcium silicate
particles together. On the other hand,
aluminium hydroxide fills the interstices (an
intervening space) rendering the mass
impervious (not affording passage to a fluid).

13. Role of Gypsum - Gypsum reacts with tricalcium
aluminate.
The fast-setting tricalcium aluminate is removed to
slow down the setting process. A quick setting will
give rise to crystalline hydrated calcium aluminate.
A slower setting yields the colloidal gel that imparts
greater strength to the set mass. Thus gypsum
helps in regulating the setting time of cement

14. • Portland cement is a basic ingredient of
concrete, mortar and most non-speciality
grout. The most common use for Portland
cement is in the production of concrete.
Concrete is a composite material consisting of
aggregate (gravel and sand), cement, and
water. As a construction material, concrete
can be cast in almost any shape desired, and
once hardened, can become a structural (load
bearing) element. Portland cement may be
grey or white.

15. Portland Cement Blends
Portland cement blends are often available as inter-ground
mixtures from cement manufacturers, but
similar formulations are often also mixed from the
ground components at the concrete mixing plant.
• Portland blastfurnace cement contains up to 70 %
ground granulated blast furnace slag, with the rest
Portland clinker and a little gypsum. All
compositions produce high ultimate strength, but as
slag content is increased, early strength is reduced,
while sulfate resistance increases and heat
evolution diminishes. Used as an economic
alternative to Portland sulfate-resisting and low-heat
cements

16. • Portland flyash cement contains up to 30 % fly ash. The
fly ash is pozzolanic, so that ultimate strength is
maintained. Because fly ash addition allows a lower
concrete water content, early strength can also be
maintained. Where good quality cheap fly ash is
available, this can be an economic alternative to
ordinary Portland cement.
• Portland pozzolana cement includes fly ash cement,
since fly ash is a pozzolana, but also includes cements
made from other natural or artificial pozzolana. In
countries where volcanic ashes are available (e.g. Italy,
Chile, Mexico, the Philippines) these cements are often
the most common form in use.

17. • Portland silica fume cement. Addition of silica
fume can yield exceptionally high strengths,
and cements containing 5–20 % silica fume
are occasionally produced. However, silica
fume is more usually added to Portland
cement at the concrete mixer.

18. • White blended cements may be made using white
clinker and white supplementary materials such as
high-purity metakaolin.
• Colored cements are used for decorative purposes.
In some standards, the addition of pigments to
produce "colored Portland cement" is allowed. In
other standards (e.g. ASTM), pigments are not
allowed constituents of Portland cement, and
colored cements are sold as "blended hydraulic
cements".

19. • Very finely ground cements are made from
mixtures of cement with sand or with slag or
other pozzolan type minerals that are
extremely finely ground together. Such
cements can have the same physical
characteristics as normal cement but with
50% less cement particularly due to their
increased surface area for the chemical
reaction. Even with intensive grinding they can
use up to 50% less energy to fabricate than
ordinary Portland cements

21. quarry
loader
1. BLASTING 2. TRANSPORT
crushing
conveyor
3. CRUHING & TRANSPORTATION
dump
er
storage
at the
plant
Quarry
face
1. BLASTING : The raw materials that are used to manufacture cement (mainly limestone and
clay) are blasted from the quarry.
2. TRANSPORT : The raw materials are loaded into a dumper.
3. CRUSHING AND TRANSPORTATION : The raw materials, after crushing, are transported to the
plant by conveyor. The plant stores the materials before they are homogenized.

22. THE CEMENT MANUFACTURING PROCESS
Raw grinding and burning
Raw mill
conveyor Raw mix
1. RAW GRINDING
kiln
2. BURNING
cooling
storage
at the
plant
preheating
clinke
r
1. RAW GRINDING : The raw materials are very finely ground in order to produce the raw mix.
2. BURNING : The raw mix is preheated before it goes into the kiln, which is heated by a flame
that can be as hot as 2000 °C. The raw mix burns at 1500 °C producing clinker which, when it
leaves the kiln, is rapidly cooled with air fans. So, the raw mix is burnt to produce clinker : the
basic material needed to make cement.

23. THE CEMENT MANUFACTURING PROCESS
Grinding, storage, packing, dispatch
1. GRINDING
Gypsum and the secondary
additives are added to the clinker.
silos
dispatch
bags
2. STORAGE, PACKING, DISPATCH
clinker
storage
Finish
grinding
1.GRINDING : The clinker and the gypsum are very finely ground giving a “pure cement”.
Other secondary additives and cementitious materials can also be added to make a blended
cement.
2. STORAGE, PACKING, DISPATCH :The cement is stored in silos before being dispatched
either in bulk or in bags to its final destination.

27. Following are the three distinct operations
involved in manufacture of Portland cement
1. Mixing of raw material
2. Burning
3. Grinding
Packing of Cement

28. Test on Cement
1. Chemical Composition
2. Fineness of Cement
3. Compressive Strength of Cement
4. Tensile Strength of Cement
5. Consistency of Cement
6. Setting Time of Cement
7. Soundness of Cement

29. Varieties of CEMENT
1. Acid Resistance Cement
2. Blast Furnace Cement
3. Coloured Cement
4. High Alumina Cement
5. Pozzolana Cement
6. Quick Setting Cement
7. Rapid Hardening Cement
8. Sulphate Resistance Cement
9. White Cement