3. CEMENT
Cement is a Building material obtained by
burning and crushing of powder form ,
homogeneous and well proportioned mixture of
lime (calcareous) and clay (argillaceous material).
4. Chemicals and material
Tri-calcium silicate (Ca)
Di-calcium silicate
Tri-calcium aluminate
Tetra-calcium alumino ferrite
Other Chemicals
Lime
Silica
Alumina
Iron oxide
Magnesia
Soda and Potash
Sulphur tri-oxide
Free lime
6. Manufacturing of cement
There are 3 steps of manufacturing of
cement
2) Mixing of raw materials
3) Burning
4) Grinding
1) Mixing of raw Material :-
clay and limestone are taken in
appropriate proportion and mixed in dry
and wet condition.
2) Burning:-
mixed material is heated about 1400 –
1600 Degree celcius and cooled by
passing through coolers.
3) Grinding:-
so material obtained (clinker) is ground in
mill and 2 % to 4 % gypsum is added to
control the setting time of cement
7. T ype o C e nt
sf me
1)Ordinary Portland cement
2)Portland Pozzolana Cement
3)Sulphate Resisting Cement
4)Coloured Cement
5)Rediset Cement
6)Very high strength cement
7)Rapid Hardening Cement
8) Portland Slag Cement
9)Masonry Cement
10)Oil Well Cement
8. Ordinary Portland Cement
(is 269:1989)
Although there are many types of Cement , about 80 -90% of total
production is of Ordinary Portland Cement (OPC) only.
OPC is classified in three types of grades depending upon strength
of cement as
1)33 Grade
2)43 Grade
3)53 Grade
Faster rate of development of strength
Offers 10-20 % savings in cement consumption
33 grade cement is almost out of the market
The manufacture of OPC is decreasing in view of popularity of
blended cement on account of lower energy consumption,
environmental pollution.
9. Portland Pozzolana Cement
It is manufactured by intergrinding of OPC clinker with
10-25% of pozzolanic material
PPC produces heat of hydration and offer greater
resistance to the attack of aggressive water than OPC.
PPC can generally be used where OPC is usable
rate of development of strength unto 7 days
Suitability
It is economical
It offers durability charecteristics in marine & hydraulic
structures
Strength of PPC is higher than OPC
10. Coloured cement
(is 8042-1989)
For manufacturing of this cement ,white or grey
portland cement is used as base
Use of white cement is costly while using grey
portland cement only red & brown cement can
be produced
Consists of PPC with 5-10% of pigment
For manufacture of white portland cement
required limestone is only available around
Jodhpur(Rajasthan)
White cement is ground finer than grey cement
11. Rapid Hardening Cement
(is 8041-1990)
This cement develops higher rate of
development of strength
Suitability
-Road repair works
-In pre-fabricated concrete
construction
-In cold weather concrete
12. Storage of cement
Water proof mesonry
walls should be
provided.
Leak proof roof with
water proof cover
should be provided.
Ground should be
drained away to
prevent from rain
water
13. Storage of cement bags
Bags should not be
allowed to directly rest on
the walls.
Not more than 15 bags
be piled over the other.
If cement is to be stored
in mansoon or for long
period piles should be
covered by polythene
sheet.
14. Field Tests for cement
Cement should be of uniform color.
When small sample of cement is rubbed
between fingers ,it should feel smooth and
cool.
There should no lumps in the cement.
15. Laboratory tests of cement
1)Fineness :-
This test is varified by using I.S. sieve No.9.
-now gentle sieving is done for fifteen minutes.
-The residue left is measured this should not be exceed
10 % by weight of the sample of the cement.
2)Consistency:-
This is a test sonducted to estimate quantity
of water to be mixed with cement.
3) Soundness of cement ;-
Due to excess of lime in the cement expansion of cement
occurs, that should be minimized.
16. 4)Setting time :-
The object of this test is
to make distinction
between normal setting
time and final setting
time. This test can be
conducted by using
Vicat apparatus.
17. References
S.Ramamrutham ,Basics of civil
Engineering,Dhanpat rai publishing
company,New Delhi.
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