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TYPES OF CEMENT:
Following are the different types of
cement used in construction works.
1. RAPID HARDENING CEMENT:
Rapid hardening cement is very
similar to ordinary portland cement (OPC). It contains higher c3s content and
finer grinding. Therefore it gives greater strength development at an early
stage than OPC. The strength of this cement at the age of 3 days is almost same
as the 7 days strength of OPC with the same water-cement ratio.
The main advantage of using rapid
hardening cement is that the formwork can be removed earlier and reused in
other areas which save the cost of formwork. This cement can be used in
prefabricated concrete construction, road works, etc.
2. LOW HEAT CEMENT:
Low heat cement is manufactured by
increasing the proportion of C2S and by decreasing the C3S and C3A content.
This cement is less reactive and its initial setting time is greater than OPC.
This cement is mostly used in mass concrete construction.
3. SULFATE RESISTING CEMENT:
Sulfate resisting cement is made by
reducing C3A and C4AF content. Cement with such composition has excellent
resistance to sulfate attack. This type of cement is used in the construction
of foundation in soil where subsoil contains very high proportions of sulfate.
4. WHITE CEMENT:
White cement is a type of ordinary
Portland Cement which is pure white in color and has practically the same
composition and same strength as OPC. To obtain the white color the iron oxide
content is considerably reduced. The raw materials used in this cement are
limestone and china clay.
This cement, due to its white color,
is mainly used for interior and exterior decorative work like external
renderings of buildings, facing slabs, floorings, ornamental concrete products,
paths of gardens, swimming pools etc.
5. PORTLAND POZZOLANA CEMENT:
Portland pozzolana cement is produced
either by grinding together, portland cement clinkers and pozzolana with the
addition of gypsum or calcium sulfate or by intimately and uniformly blending
portland cement and fine pozzolana.
It produces lower heat of hydration
and has greater resistance to attack of chemical agencies than OPC. Concrete
made with PPC is thus considered particularly suitable for construction in sea
water, hydraulic works and for mass concrete works.
6. HYDROPHOBIC CEMENT:
Hydrophobic cement is manufactured by
adding water repellant chemicals to ordinary portland cement in the process of
grinding. Hence the cement stored does not spoiled even during monsoon. This
cement is claimed to remain unaffected when transported during rains also.
Hydrophobic cement is mainly used for the construction of water structures such
dams, water tanks, spillways, water retaining structures etc.
7. COLORED CEMENT:
This Cement is produced by adding 5-
10% mineral pigments with portland cement during the time of grinding. Due to
the various color combinations this cement is mainly used for interior and
exterior decorative works.
8. WATERPROOF PORTLAND CEMENT:
Waterproof cement is prepared by
mixing with ordinary or rapid hardening cement, a small percentage of some
metal stearates (Ca, Al, etc) at the time of grinding. This cement is used for
the construction of water-retaining structure like tanks, reservoirs, retaining
walls, swimming pools, dams, bridges, piers etc.
9. PORTLAND BLAST FURNACE CEMENT:
In this case, the normal cement
clinkers are mixed with up to 65% of the blast furnace slag for the final
grinding. This type of cement can be used with advantage in mass concrete work
such as dams, foundations, and abutments of bridges, retaining walls , construction
in sea water.
10. AIR ENTRAINING CEMENT:
It is produced by air entraining
agents such as resins, glues, sodium salts of sulfate with ordinary portland
cement.
11. HIGH ALUMINA CEMENT:
High alumina cement (HAC) is a
special cement, manufactured by mixing of bauxite ( aluminum ore) and lime at a
certain temperature. This cement is also known as calcium aluminum cement
(CAC). The compressive strength of this cement is very high and more workable
than ordinary portland cement.
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