Cement is produced by burning limestone and clay at high temperatures. The resulting clinker is ground with gypsum to produce cement powder. There are different types of cement including natural cement, Portland cement, and special cements. Cement hydration results in products like calcium silicate hydrate and calcium hydroxide that provide strength and bonding. Sulphate resisting cement contains less tricalcium aluminate to improve durability in sulphate-containing environments. Cement is widely used in construction for applications such as concrete structures.

1. CEMENT

2. CEMENT
• It can be defined as material having adhesive and cohesive
properties which make it capable of bonding material fragments
in to a compact mass.
• Cement is obtained by burning together, in a definite proportion,
a mixture of naturally occurring calcareous (containing calcium
carbonate or lime) and argillaceous (containing alumina)
material to be partial fusion at high temperature about 1450◦c.
• The product obtained on burning called clinker, is cooled and
ground to the required fineness. During grinding of clinker
gypsum (CaSO4) is added to it to adjust the setting time and to
improve the soundness of cement.

3. • Classification of cements
• 1. Natural cement
- burning limestone containing 20-40 % clay and crushing it to powder.
- brown in colour and sets very quickly when mixed with water.
2. Artificial cement
(i) portland cement - ordinary portland cement
- rapid hardening cement
- low heat cement
(ii) special cements – quick setting cement
- high alumina cement
- blast furnace cement
- calcium chloride cement
- white cement
- coloured cement
- expanding cement
- super sulphate cement
- sulphate reisting cement

4. • Early History of Cement
• In ancient times, Romans, Egyptians and Indians used some kind of
cementing materials in their construction
• Egyptians used burnt gypsum (CaSo4) as cementing materials
- the analysis of mortar used in Great pyramid showed that it contained
81.5% of calcium sulphate and about 9.5% of calcium carbonate
• Not much is known about the cementing materials used by Indians in the
construction of cities of Harappa and Mohenjo-Daro.
• Early Romans & Greeks used cementing materials obtained by
calcinations (burning) of lime stone.
• Latter Romans & Greeks learnt that cementing materials may be
obtained by mixing volcanic ash and tuff with lime stone, sand and water.
- the tuff used in the mix was found in the village Pozzuoli near the mount
pozzolona. Afterwards any material natural of artificial having the same
properties as those of tuff or ash was called pozzolona.

5. • Early History of Cement……
• In the absence of natural volcanic ash, Romans used powdered pottery or
tiles as pozzolona,
• In India Surkhi (brick powder) has been used as pozzolona in mortar
• Romans added milk, blood & lard in the mix to improve the workability
• The blood Hemoglobin is a powerful air entraining agent and plasticizer.
• After 1756, John Smeaton carried out extensive experiments to find out the
best material to withstand severe action of sea water.
• In 1796 hydraulic cement was produced by burning the nodules of
argillaceous lime stones
- in 1800 it was given the name Roman cement
- it was in use till 1850 then OPC was introduced

7. • History of OPC
• Invented in 1824 by Joseph Aspdin, a brick layer of Leeds (Yorkshire)
England
- Prepared by heating a mixture of finely divided clay and hard lime
stone in furnace until CO2 had been driven off.
• 1845 – modern cement was made by Issac Johnson
• In India,OPC was first manufactured in 1904 near madras
• Bet’n 1912 & 1913, the India cement Co.was established at Porbander
produced 1000 tons(1914).
• By 1918 three more cement factories were established in India and
produced about 8500 tons every year
• During 1951 -56 production rose from 2.69 million tons to 4.6 million tons.
• By 1969 the production of cement in India was 13.2 million tons (9th place
in the world USSR being the first with production of 89.4 million tons)
• In 2002 the production in India crossed 100 million tons (2nd position after
China)

9. Raw materials
Oxide % Function
Lime, CaO 60-65 Bulk to cement,
Lesser - sets quickly and reduction in strength
More - unsound, expansion & disintegration
Silica, SiO2 17-25 Imparts strength
Alumina, Al2O3 3-8 Setting, imparts quick setting, excess make weak
Iron oxide, Fe2O3 0.5-6 Grey colour, strength to cement & hardness
Magnesia, MgO 0.5-4 soundness
Sulphur trioxide,
SO3
1-2 Reduce the setting time, combined with lime
gives calcium sulphate
Soda(Na2O) and
Potash (K2O)
(alkalis)
0.5-1 react with agg. Cause disintegration of concrete,
affect the rate of gain of strength

13. Major compounds of cement
Tricalcium silicate (3CaO.SiO2) C3S 54.1%
Dicalcium silicate (2CaO.SiO2) C2S 16.6%
Tricalcium aluminate (3CaO.Al2O3) C3A 10.8%
Tetra calcium alumino ferrite
(4CaO. Al2O3.Fe2O3) C4AF 9.1%
The calculation of main compounds in cement
C3S = 4.07(CaO) - 7.6(SiO2) - 6.72(Al2O3) - 1.43(Fe2O3) - 2.85(SO3)
C2S = 2.87(SiO2) - 0.754(C3S)
C3A = 2.65(Al2O3) - 1.69(Fe2O3)
C4AF = 3.04(Fe2O3)

14. Hydration of cement
• Upon hydration, both C3S and C2S give the same product called calcium silicate
hydrate (C3S2H3) and calcium hydroxide (Ca (OH)2)
2 C3S + 6 H --------> C3S2H3 + 3 Ca (OH)2
(100) (24) (75) (49)
2 C2S + 4 H ------ > C3S2H3 + Ca (OH)2
(100) (21) (99) (22)
Note:C3S2H3 – mainly responsible for strength for bond and strength
Ca (OH)2 is responsible for sulphate attack , to compensate this add poz.mat
• Tricalcium silicate(C3S ) giving a faster rate of reaction accompanied by greater heat
evolution develops early strength.
• On the other hand, dicalcium silicate (C2S) hydrates and hardens slowly and
provides much of the ultimate strength.
• C3S and C2S need approximately 24% and 21% water by weight respectively for
chemical reaction but C3S liberates 2 times as much calcium hydroxide on hydration
as C2S. however C2S provides more resistance to chemical attack.
• The amount of Ca(OH)2 is not a desirable product in the concrete mass as it is
soluble in water and may get leached out making the concrete porous, weak and not
durable.

15. • Ca(OH)2 also reacts with sulphates present in water or soil to form calcium
sulphates which further reacts with C3A and cause deterioration of concrete
• The only advantage of calcium hydroxide is that it being alkaline in nature,
maintains the Ph value of water around 13 in the concrete which reduces the
corrosion of reinforcement.
• The reaction of C3A with water is very rapid and produces enormous heat. The
hydrated product obtained is calcium alumina hydrate (C3AH6) which will bind
the materials.
The approximate reaction being
C3A + 6 H -----> C3AH6
(100) (40) (140)
The reaction of C4AF with water gives a product called calcium ferrite hydrate
(CFH) in addition to calcium alumina hydrate. It does not contribute any
strength to concrete. The calcium ferrite hydrate shows a comparatively higher
resistance to attack of sulphate than the hydrates of calcium aluminates. The
reaction being
• C4AF + 7 H -----> C3AH6 + CFH

16. • Applications
– Hydraulic structures
– Mass concreting works
– Marine structures
– Masonry mortars and plastering
– Under aggressive conditions.
– All other application where OPC is used.

17. Sulphate Resisting Portland Cement (SRC)
C3A is restricted to less than 5 %
2 C3A + C4AF lower than 25%
use of SRC is particularly beneficial in such
conditions where the concrete is exposed to the risk
of deterioration due to sulphate attack.
Ex: in contact with soils and ground waters
containing excessive amounts of sulphates as
well as for concrete in seawater or exposed directly
to seacoast.

18. Sulphate attack
• The Ca(OH)2 react with sulphate gives calcium sulphate
resulting in the formation of gypsum (CaSO4.2H2O)
with an increase in volume of solid phase by 124%
This calcium sulphate reacts with hydrated product of
C3A and C4AF forms calcium sulpho aluminate which
causes expansion of cement ( increase the solid phase
by 227%), hence the disintegration of concretee
This increase in volume by any type of reaction is
called g* attack.

19. • Applications
– Foundations, piles
– Basements and underground structures
– Sewage and Water treatment plants
– Chemical, Fertilizers and Sugar factories
– Food processing industries and Petrochemical
projects
– Coastal works.
– Also for normal construction works where opc is
used .

41. Physical Characteristics of OPC (BIS Requirement)
grade
Of
cement
Fineness
(sq.m/kg)
Min
Soundness
Le Chate Auto
-lier Clave
Max Max
Setting Time
(Minutes)
Initial Final
Min Max
Compressive Strength
(MPa)
3day 7day 28day
53 225 10 mm 0.8 % 30 600 27 37 53
43 225 10 mm 0.8 % 30 600 23 33 43
33 225 10 mm 0.8 % 30 600 16 22 33

42. Portland Pozzolana Cement (PPC)
– OPC clinker along with gypsum and pozzolanic
materials in certain proportions either inter-grinding
or grinding separately and thoroughly blending
– Pozzolana is a natural or artificial material containing
silica in a reactive form, no cementitious properties,
chemically react with calcium hydroxide to form
stable calcium silicates which have cementitious
properties.
– PPC produces less heat of hydration and offers
greater resistance to the attack of aggressive waters