Cement is a binding material made of a mixture of calcareous, siliceous, and argillaceous substances. There are two main processes for manufacturing cement - the dry process and wet process. In the dry process, raw materials are ground without water, while in the wet process water is added during grinding. The ground raw materials are then burned in a kiln at high temperatures to form clinker, which is then ground with gypsum. There are different types of cement used for various purposes, and cement is tested for qualities like fineness, setting time, and compressive strength.

1. PRESENTATION ON
CEMENT
-LGHBOND14

2. CEMENT:
CEMENT ISTHE MIXTURE OF CALCAREOUS, SILICEOUS,
ARGILLACEOUS AND OTHER SUBSTANCES. CEMENT IS USED AS A
BINDING MATERIAL IN MORTAR, CONCRETE, ETC.

3. CHEMICAL COMPOSITION OF
CEMENT
CHEMICALS % OF COMPOSITION
LIME 63 %
SILICA 22 %
ALUMINA 06 %
IRON OXIDE 03 %
GYPSUM 01-04 %

4. MANUFACTURING OF CEMENT:
(1) Mixing and crushing of raw materials
a. Dry process
b.Wet process
(2) Burning
(3) Grinding

5. (A) DRY PROCESS:
• In this process calcareous material such as lime stone (calcium
carbonate) and argillaceous material such as clay are ground
separately to fine powder in the absence of water and then are
mixed together in the desired proportions.Water is then added to
it for getting thick paste and then its cakes are formed, dried and
burnt in kilns.This process is usually used when raw materials are
very strong and hard.
 In this process, the raw materials are changed to powdered form in
the absence of water.

6. (B) WET PROCESS:
 In this process, the raw materials are changed to powdered form in the
presence of water. In this process, raw materials are pulverized by using a
Ball mill, which is a rotary steel cylinder with hardened steel balls.When the
mill rotates, steel balls pulverize the raw materials which form slurry (liquid
mixture).The slurry is then passed into storage tanks, where correct
proportioning is done.
 Proper composition of raw materials can be ensured by using wet process
than dry process. Corrected slurry is then fed into rotary kiln for burning.
 This process is generally used when raw materials are soft because
complete mixing is not possible unless water is added.Actually the purpose
of both processes is to change the raw materials to fine powder.

7. (2) BURNING:
 Corrected slurry is feed to rotary kiln, which is a 150-500
feet long, 8-16 feet in diameter and temperature
arrangement is up to 1500-1650 degree C.
 At this temperature slurry losses moisture and forms into
small lumps, after that changes to clinkers.
 Clinkers are cooled in another inclined tube similar to
kiln but of lesser length.

8. (3) GRINDING:
 Now the final process is applied which is grinding of clinker, it
is first cooled down to atmospheric temperature.
 Grinding of clinker is done in large tube mills. After proper
grinding gypsum (Calcium sulphate Ca SO4) in the ratio of 01-
04 % is added for controlling the setting time of cement.
 Finally, fine ground cement is stored in storage tanks from
where it is drawn for packing.

9. TYPES OF CEMENT:
 Ordinary Portland Cement
 Sulphate Resisting Cement
 Rapid Hardening Cement (or) High Early Strength cement
 Quick Setting Cement
 Low Heat Cement
 High Alumina Cement
 Air Entraining Cement
 White Cement

10. (1) ORDINARY PORTLAND CEMENT:
 It is the variety of artificial cement. It is called Portland
cement because on hardening (setting) its colour
resembles to rocks near Portland in England.
 It was first of all introduced in 1824 by Joseph Asp din, a
bricklayer of Leeds, England.

11. CHEMICAL COMPOSITIONOF
O.P.C:O.P.C has the following approximate chemical composition:
NAME FORMULA % OF COMPOSITION
LIME CaO 60-63%
SILICA SiO2 17-25%
ALUMINA Al2O3 03-08%
 MAIN CONSTITUENTS

12.  AUXILIARYCONSTITUENTS
NAME FORMULA % OF COMPOSITION
IRON OXIDE Fe2 O3 0.5- 06%
MAGNESIA MgO 1.5- 03%
SULPHURTRI-OXIDE SO3 01- 02%
GYPSUM CaSO4. 2H2O2 01 to 04%

13. FUNCTIONS OF CEMENT
MANUFACTURING
CONSTITUENTS

14. (I) LIME (CAO)
 Lime forms nearly two-third (2/3) of the cement.Therefore
sufficient quantity of the lime must be in the raw materials
for the manufacturing of cement.
 Its proportion has an important effect on the cement.
Sufficient quantity of lime forms di-calcium silicate (C2SiO2)
and tri-calcium silicate in the manufacturing of cement.
 Lime in excess, causes the cement to expand and
disintegrate.

15. (II) SILICA (SIO2)
 The quantity of silica should be enough to form di-calcium
silicate (Ca2 SiO2) and tri-calcium silicate in the
manufacturing of cement.
 Silica gives strength to the cement. Silica in excess causes
the cement to set slowly.

16. (III) ALUMINA (AL2O3)
 Alumina supports to set quickly to the cement.
 It also lowers the clinkering temperature. Alumina in excess,
reduces the strength of the cement.
(iv) Iron Oxide (Fe2O3)
 Iron oxide gives colour to the cement.

17. (V) MAGNESIA (MGO)
It also helps in giving colour to the cement. Magnesium in excess
makes the cement unsound.
(vi) Calcium Sulphate (or) Gypsum (Ca SO4)
At the final stage of manufacturing, gypsum is added to increase the
setting of cement.

18. (2) SULPHATE RESISTING CEMENT
It is modified form of O.P.C and is specially manufactured to resist the
sulphates. In certain regions/areas where water and soil may have
alkaline contents and O.P.C is liable to disintegrate, because of
unfavorable chemical reaction between cement and water, S.R.C is
used. This cement contains a low %age of C3A not more than
05%.This cement requires longer period of curing. This cement is used
for hydraulic structures in alkaline water and for canal and water
courses lining. It develops strength slowly, but ultimately it is as strong
as O.P.C.

19. (3) RAPID HARDENING CEMENT
This cement contains more %age of C3S and less %age of C2S. This is
infact high early strength cement. The high strength at early stage is
due to finer grinding, burning at higher temperature and increased lime
content. The strength obtained by this cement in 04 days is same as
obtained by O.P.C in 14 days. This cement is used in highway slabs
which are to be opened for traffic quickly. This is also suitable for use in
cold weather areas. One type of this cement is manufactured by adding
calcium chloride (CaCl2) to the O.P.C in small proportions. Calcium
chloride (CaCl2) should not be more than 02%. When this type of
cement is used, shuttering material can be removed earlier.

20. (4) QUICK SETTING CEMENT
When concrete is to be laid under water, quick setting cement is to
used. This cement is manufactured by adding small %age of aluminum
sulphate (Al2SO4) which accelerates the setting action. The setting
action of such cement starts with in 05 minutes after addition of water
and it becomes stone hard in less than half an hour.

21. (5) LOW HEAT CEMENT
In this cement the heat of hydration is reduced by tri
calcium aluminate (C3 A ) content. It contains less %age of
lime than ordinary port land cement. It is used for mass
concrete works such as dams etc.

22. (6) HIGH ALUMINA CEMENT
This cement contains high aluminate %age usually
between 35-55%. It gains strength very rapidly with in 24
hours. It is also used for construction of dams and other
heavy structures. It has resistance to sulphates and action
of frost also.

23. (7) AIR ENTRAININGCEMENT
This type of cement was first of all developed in U.S.A to produce such
concrete which would have resistance to weathering actions and
particularly to the action of frost. It is found that entrainment of air or
gas bubbles while applying cement, increases resistance to frost action.
Air entraining cement is produced by grinding minute air entraining
materials with clinker or the materials are also added separately while
making concrete. Entrainment of air also improves workability and
durability. It is recommended that air contents should be 03-04 % by
volume.
Natural resins, fats, oils are used as air entraining agents.

24. (8) WHITE CEMENT
This cement is called snow Crete. As iron oxide gives the grey colour to cement,
it is therefore necessary for white cement to keep the content of iron oxide as
low as possible. Lime stone and china clay free from iron oxide are suitable for
its manufacturing. This cement is costlier than O.P.C. It is mainly used for
architectural finishing in the buildings.

25. TO CHECKTHE QUALITY OF CEMENT IN
THE FILED
1.Colour greenish grey.
2.One feels cool by thrusting one’s hand in the cement bag.
3.It is smooth when rubbed in between fingers.
4.A handful of cement thrown in a bucket of water should float.

26. QUALITY TESTS OF CEMENT
(1) Fineness Test,
(2) Consistency test / setting time test
(3) Setting Time Test
(4) Compressive strength test

27. (1) FINENESS TEST
Finer cements react quicker with water and develop early strength,
though the ultimate strength is not affected. However finer cements
increase the shrinkage and cracking of concrete. The fineness is tested
by
Sieve analysis:-
Break with hands any lumps present in 100 grams of cement placed
in IS sieve No.9 and sieve it by gentle motion of the wrist for 15
minutes continuously. The residue when weighed should not exceed
10 percent by weight of the cement sample.

28. (2) CONSISTENCY TEST /SETTING
TIME TEST
This test is performed to determine the quantity of water required to
produce a cement paste of standard or normal consistency.
Standard consistency of cement paste may be defined as the consistency
which permits the Vicate’s plunger (10 mm, 40 to 50 mm in length) to
penetrate to a point 5 mm to 7 mm from the bottom ( or 35 mm to 33
mm from top) of Vicat mould. When the cement paste is tested within the
gauging time ( 3 to 5 minutes) after the cement is thoroughly mixed with
water.
Vicat apparatus is used for performing this test.

29. (3) SETTING TIME TEST
In cement hardening process, two instants are very important, i.e.
initial setting and final setting.
Initial Setting Time
The process elapsing between the time when water is added to the
cement and the time at which the needle ( 1 mm square or 1.13 mm
dia., 50 mm in length) fails to pierce the test block ( 80 mm dia. and
40 mm high) by about 5 mm, is known as Initial Setting Time of
Cement.

30. FINAL SETTING TIME
The process elapsing between the time when water is added to the
cement and the time at which a needle used for testing final setting upon
applying gently to the surface of the test block, makes an impression
thereon, while the attachment of the needle fails to do so, is known as
final Setting Time of Cement.

31. (4) COMPRESSIVE STRENGTH
TEST OF CEMENT
This test is very important. In this test, three moulds of (face area
50 cm2) are prepared and cured under standard temperature
conditions and each cube tested by placing it between movable
jaws of the compressive strength testing machine. The rate of
increasing load is zero in the beginning and varies at 350 kg/cm2
per minute. The load at which the cube gets fractured divided by the
cross sectional area of the cube, is the compressive strength of the
cube. The average of the compressive strengths of three cubes is
the required compressive strength of the cement sample

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