Cement is a binding agent used in construction that hardens when mixed with water. It is produced by heating limestone and clay at high temperatures, forming clinker which is then finely ground with gypsum. The key compounds formed are tricalcium silicate, dicalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite. Different types of cement include rapid hardening cement, extra rapid hardening cement containing calcium chloride, and sulphate resisting cement for use where sulphates are present. Cement is tested for fineness, consistency, setting time, strength and soundness to ensure quality for construction projects.

1. CEMENT
BY
M.ANIL KUMAR

2. INTRODUCTION
• Cement is a binding material used in the construction.
• We can not imagine the modern construction with out cement.
• Cement is used in the concrete to form bond between the aggregates.
• Cement and aggregate together forms dense and strong concrete mix.
• Cement was invented by joseph aspdin.
• The normal cement is called portland cement because, when the cement
hardens it’s look like a hard stone available in portland in England.
• In india portland cement was first manufactured in 1904 near Chenni

3. CHEMICAL COMPOSITION OF OPC

4. Functions of cement ingredients:
 Lime:
• Lime is calcium oxide or calcium hydroxide.
Presence of lime in a sufficient quantity is required to form silicates and
aluminates of calcium.
• Deficiency in lime reduces the strength of cement.
• Deficiency in lime causes cement to set quickly.
• Excess lime make cement unsound.
• Excessive presence of lime cause cement to expand and disintegrate.
 Silica:
• Silicon dioxide is known as Silica, chemical formula SiO2.Sufficient
quantity of silica should be present in cement to form dicalcium and
tricalcium silicate.
• Silica imparts strength to cement.
• Silica usually present to the extent of about 30 percent cement.

5.  Alumina:
• Alumina is Aluminium oxide. Chemical formula is Al2O3.
• Alumina imparts quick setting property to the cement.
• Clinkering temperature is lowered by the presence of requisite quantity of
alumina.
• Excess alumina weaken the cement.
 Magnesia:
• Magnesium oxide Chemical formula is MgO.
• Magnesia should not be present more than 2% in cement.
• Excess magnesia will reduce the strength of the cement.

6.  Iron oxide:
• Chemical formula is Fe2O3.
 Iron oxide imparts colour to cement.
• It acts as a flux.
• At a very high temperature it imparts into chemical reaction with
calcium and aluminium to form tricalcium aluminoferrite.
• Tricalcium aluminoferrite imparts Hardness and strength to cement.
 Calcium Sulphate:
• Chemical formula is CaSO4.This is present in cement in the form of
gypsum(CaSO4.2H2O)
• It slows down or retards the setting action of cement.

7.  Sulphur Trioxide:
•Chemical formula is SO3
.Should not be present more than 2%.
•Excess Sulphur Trioxide causes cement to unsound.
 Alkaline:
Should not be present more than 1%.
•Excess Alkaline matter causes efflorescence.

8.  BOGUES COMPOUNDS:
• The various constituents combine in burning and form cement clinker. The
compounds formed in the burning process have the properties of setting and
hardening in the presence of water.
• They are known as Bogue compounds after the name of Bogue who
identified them.
These compounds are as follows:
• Alite (Tricalcium silicate or C3S), Belite (Dicalcium silicate or C2S), Celite
(Tri calcium alluminate or C3A) and Felite (Tetra calcium alumino ferrite or
C4AF).

10.  It is to be noted that for simplicity’s sake abbreviated notations are used. C
stands for CaO, S stands for SiO2, A for Al2O3, F for Fe2O3 and H for H2O.
 The equations suggested by Bogue’s for calculating the percentages of major
compounds are given below.
• C3S = 4.07 (CaO) – 7.60 (SiO2) – 6.72 (Al2O3) – 1.43 (Fe2O3) – 2.85 (SO3)
• C2S = 2.87 (SiO2) – 0.754 (3CaO.SiO2)
• C3A = 2.65 (Al2O3) – 1.69 (Fe2O3)
• C4AF= 3.04 (Fe2O3)

11. • There are two types of process in manufacturing of cement :
1) Dry Process
2) Wet Process.
 Dry process is preferable than Wet process
 Because wet process is uneconomical .

12. THE CEMENT MANUFACTURING PROCESS
1. BLASTING : The raw materials that are used to manufacture cement (mainly limestone and clay) are blasted
from the quarry.
Quarry face
1. BLASTING 2. TRANSPORT
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.
quarry
3. CRUSHING & TRANSPORTATION
2. TRANSPORT : The raw materials are loaded into a dumper.
crushing
conveyor
dumper
storage at
the plant
loader

13. THE CEMENT MANUFACTURING PROCESS
1. RAW GRINDING : The raw materials are very finely ground in order to produce the raw mix.
1. RAW GRINDING
Raw grinding and burning
2. BURNING
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.
conveyor
Raw mix
kiln
cooling
preheating
clinker
storage at
the plant
Raw mill

14. THE CEMENT MANUFACTURING PROCESS
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.
1. GRINDING
Grinding, storage, packing, dispatch
2. STORAGE, PACKING, DISPATCH
2. STORAGE, PACKING, DISPATCH :The cement is stored in silos before being dispatched
either in bulk or in bags to its final destination.
clinker
storage
Gypsum and the secondary additives are added
to the clinker.
silos
dispatch
bags
Finish grinding

15. HYRDATION OF CEMENT
 Anhydrous cement does not bind fine and coarse aggregate.
 It acquires adhesive property only when mixed with water.
 The chemical reactions that take place between cement and water is
referred as hydration of cement.
 The chemistry of concrete is essentially the chemistry of the reaction
between cement and Water.

16. Heat of Hydration
 The reaction of cement with water is exothermic.
 The reaction liberates a considerable quantity of heat.
 This liberation of heat is called heat of hydration.
 This is clearly seen if freshly mixed cement is put in a vaccum flask and
the temperature of the mass is read at intervals.
 The study and control of the heat or hydration becomes important in the
construction of concrete dams and other mass concrete constructions.

17. Water requirements of hydration
 It has been brought out earlier that C3S requires 24% or water by weight of
cement and C2S requires 21%.
 It has also been estimated that on an average 23% of water by weight of
cement is required for chemical reaction with Portland cement compounds
 . This 23% of water chemically combines with cement and, therefore, it is
called bound water.
 A certain quantity of water is imbibed within the gel-pores. This water is
known as gel-water. It can be said that bound water and gel-water are
complimentary to each other.

18. Types of cement

19. Types of cement

20.  Rapid hardening cement:
• This cement is similar to ordinary Portland cement. As the name indicates it
develops strength rapidly and as such it may be more appropriate to call it as
high early strength Cement
• Rapid hardening cement develops at the age of three days, the same strength
as that is expected of ordinary Portland cement at seven days.
The use of rapid heading cement is recommended in the following situations:
(a) In pre-fabricated concrete construction.
(b) Where formwork is required to be removed early for re-use elsewhere,
(c ) Road repair works,
(d ) In cold weather concrete where the rapid rate of development of strength
reduces the vulnerability of concrete to the frost damage.

21.  Extra rapid hardening cement:
• Extra rapid hardening cement is obtained by inter grinding calcium chloride
with rapid hardening Portland cement.
• The normal addition of calcium chloride should not exceed 2 percent by weight
of the rapid hardening cement.
• It is necessary that this cement should not be stored for more than a month.
• Extra rapid hardening cement accelerates the setting and hardening process.
• A large quantity of heat is evolved in a very short time after placing.
• The acceleration of setting, hardening and evolution of this large quantity of
heat in the early period of hydration makes the cement very suitable for
concreting in cold weather.
• The strength of extra rapid hardening cement is about 25 per cent higher than
that of rapid hardening cement at one or two days and 10–20 per cent higher
at 7 days.

22.  Sulphate resisting cement:
• Ordinary Portland cement is susceptible to the attack of sulphates, in particular to
the action of magnesium sulphate.
• To remedy the sulphate attack, the use of cement with low C3A content is found
to be effective. Such cement with low C3 A and comparatively low C4AF
content is known as Sulphate Resisting Cement
• The use of sulphate resisting cement is recommended under the following
conditions:
• (a ) Concrete to be used in marine condition;
• (b ) Concrete to be used in foundation and basement, where soil is infested with
sulphates;
• (c ) Concrete used for fabrication of pipes which are likely to be buried in
marshy region or sulphate bearing soils;
• (d ) Concrete to be used in the construction of sewage treatment works.

23. TESTING OF CEMENT
 Field testing
 Laboratory testing
For minor works field test is sufficient.
 Field testing:
• No visible lumps
• Color-greenish grey
• Thrust your hand into bag –you should feel cool & no lumps
• Take pinch of cement & feel between fingers-you should feel smooth
• Throw a hand full of cement into a bucket full of water- particles should float
for some time before they sink.

24. • Make a stiff paste with 100gm of cement & little water & take it to the
bottom of a bucket full of water on a glass plate.
• It should not lose its shape while taking it down
• After 24 hours it should retain its original shape & at the same time it
should attain some strength
• For important & major works laboratory tests are essential.

25. LABORATORY TESTS
• Fineness Test
• Standard consistency test
• Setting Time Test
• Strength Test
• Soundness Test

26.  FINENESS TEST :
Fineness Of Cement Is Tested In Two Ways:
 By Sieving
 By Determination Of Specific Surface(Total Surface Of All The
Particles In 1gm Of Cement) By Air Permeability Apparatus
 Sieve method:
• Continuously Sieve 100gm Of Cement Having No Lumps For
15min.
• The Residue Left On The Sieve Shell Not Exceed 10% For Ordinary
Cement
• Is Sieve No.9(90 Microns) Is Used To Sieve
• Sieve Test Is Rarely Used.

27.  STANDARD CONSISTENCY TEST:
• The purpose of this test is to determine the percentage of water required
for preparing cement pastes for other tests.
• Take 300 gm of cement and add 30 percent by weight or 90 gm of water
to it.
• Mix water and cement thoroughly.
• Fill the mould of Vicat apparatus and the gauging time should be 3 to 4
minutes.
• Vicat apparatus consists of a needle is attached a movable rod with an
indicator attached to it.
• There are three attachments: square needle, plunger and needle with
annular collar.

28. • The plunger is attached to the movable rod. The plunger is gently
lowered on the paste in the mould.
• The settlement of plunger is noted. If the penetration is between 5
mm to 7 mm from the bottom of mould, the water added is correct. If
not process is repeated with different percentages of water till the
desired penetration is obtained

29. STANDARD CONSISTENCY TEST

30.  Setting time :
• This test is used to detect the deterioration of cement due to storage. The
test is performed to find out initial setting time and final setting time.
• Cement mixed with water and cement paste is filled in the Vicat mould.
• Square needle is attached to moving rod of Vicat apparatus.
• The needle is quickly released and it is allowed to penetrate the cement
paste.
• In the beginning the needle penetrates completely. The procedure is
repeated at regular intervals till the needle does not penetrate
completely.(up to 5mm from bottom)
• Initial setting time =<30min for ordinary Portland cement and 60 min for
low heat cement.

31. • The cement paste is prepared as above and it is filled in the Vicat
mould.
• The needle with annular collar is attached to the moving rod of the
Vicat apparatus.
• The needle is gently released. The time at which the needle makes an
impression on test block and the collar fails to do so is noted.
• Final setting time is the difference between the time at which water
was added to cement and time as recorded in previous step,and it is
=<10hours.

32.  Soundness Test:
• It is very important that the cement after setting shall not undergo any appreciable
change of volume.
• Certain cements have been found to undergo a large expansion after
• setting causing disruption of the set and hardened mass.
• This will cause serious difficulties for the durability of structures when such
cement is used.
• The testing of soundness of cement, to ensure that the cement does not show any
appreciable subsequent expansion is of prime importance.
• The unsoundness in cement is due to the presence of excess of lime than that could
be combined with acidic oxide at the kiln.
• This is also due to inadequate burning or insufficiency in fineness of grinding or
thorough mixing of raw materials.

33. • It is also likely that too high a proportion of magnesium content or calcium
sulphate content may cause unsoundness in cement.
• For this reason the magnesia content allowed in cement is limited to 6 per
cent.
• Unsoundness in cement is due to excess of lime, excess of magnesia or
excessive proportion of sulphates.
• Unsoundness in cement does not come to surface for a considerable period
of time.

34.  Strength Test
• The compressive strength of hardened cement is the most important of all the
properties.
• Strength tests are not made on neat cement paste because of difficulties of
excessive shrinkage and subsequent cracking of neat cement.
• Take 555 gms of standard sand (Ennore sand), 185 gms of cement (i.e., ratio
of cement to sand is 1:3) in a non-porous enamel tray and mix them with a
trowel for one minute.
• Then add water of quantity (P /4 + 3.0 per cent) of combined weight of
cement and sand and mix the three ingredients thoroughly until the
mixture is of uniform colour.
• The time of mixing should not be less than 3 minutes nor more than 4
minutes.

35. • Immediately after mixing, the mortar is filled into a cube mould of size 7.06
cm. The area of the face of the cube will be equal to 50 sq.cm.
• Compact the mortar either by hand compaction in a standard specified
manner or on the vibrating equipment (12000 RPM) for 2 minutes.
• Keep the compacted cube in the mould at a temperature of 27°C ± 2°C and at
least 90 per cent relative humidity for 24 hours.
• The compressive strength shall be the average of the strengths of the three
cubes for each period respectively.