Cement
is the widely used, well known and best among binding material. To insure various
demands due to various needs and requirement varieties of Cement have been manufactured.
Ordinary Portland Cement is the most commonly used Cement and all other
variants are derived from it. Following are the types of Portland Cement.
TYPE OF PORTLAND CEMENT
1. Ordinary
Portland Cement (Type I)
2. Modified
Portland Cement
3. Rapid
Hardening or High Early Strength Portland Cement (Type III)
4. Quick
Setting Cement
5. Low
Heat Portland Cement (Type IV)
6. Sulphate
Resistant Portland Cement (Type V)
7. Water
Repellent Portland Cement
8. Water
Proof Portland Cement
9. High
Alumina Cement
10. Portland
Slag Cement
11. Air
Entraining Portland Cement (Type I-A, II-A, III-A)
12. Pozzolana
Portland Cement
It
is used in general construction works. All other varieties of Cement are
derived from this Cement.
·
White Cement
o
OPC with pure white color produced with white chalk
or clay free from iron oxide.
o
Instead of coal, oil fuel is used for burning.
o
Much more costly than OPC.
·
o
Suitable pigments used to impart desired color.
o
Pigments used should be chemically inert and
durable under light, sun or weather.
2. Modified Portland
Cement
·
This cement on setting develops less heat of
generation than OPC.
·
It is best suited in hot climate for civil works
construction.
3. Rapid Hardening
or High Early Strength Cement (Type III)
·
Gains strength faster than OPC. In 3 days develops
7 days strength of OPC with same water cement ratio.
o
After 24 hours – not less than 160 kg/cm2
o
After 72 hours – not less than 275 kg/cm2
·
Initial and final setting times are same as OPC.
·
Contains more tri-calcium silicate (C3S) and finely
ground.
·
Emits more heat during setting, therefore
unsuitable for mass concreting.
·
Lighter and costlier than OPC. Short curing period
makes it economical.
·
Used for structures where immediate loading is
required e.g. repair works.
4. Quick Setting
Cement
·
Sets faster than OPC.
·
Initial setting time is 5 minutes.
·
Final setting time is 30 minutes.
·
Used for concreting underwater and in running
water.
·
Mixing and placing has to be faster to avoid
initial setting prior to laying.
5. Low Heat Cement
·
Low percentage (5%) of tri-calcium aluminates (C3A)
and silicate (C3S) and high (46%) of di-calcium silicate (C2S) to keep heat
generation low.
·
It has low lime content and less compressive
strength.
·
Initial and final setting times nearly same as OPC.
·
Very slow rate of developing strength.
·
Not suitable for ordinary structures.
o
Shuttering required for long duration so cost will
increase.
o
Prolonged curing is required.
o
Structure utilization will be delayed.
6. Sulphate
Resistant Portland Cement
·
Percentage of tri-calcium Aluminate (C3A) is kept
below 5% resulting in increase in resisting power against sulphates.
·
Heat developed is almost same as Low Heat Cement.
·
Theoretically ideal cement. Costly manufacturing
because of stringent composition requirements.
·
Used for structures likely to be damaged by severe
alkaline conditions like bridges, culverts, canal lining, siphons, etc.
·
It contains a small percentage of water-proofing
material with the cement and is manufactured under the name “Aqua-Crete”.
·
The cement is prepared with ordinary or rapid
hardening cement and white cement.
·
It is used in to check moisture penetration in
basements etc.
8. Water Proof
Portland cement
·
It is prepared by mixing ordinary or rapid
hardening cement and some percentage of some metal stearate ( Ca, Al etc).
·
It is resistant to water and oil penetration.
·
It is also resistant to acids, alkaline and salt
discharged by industrial water.
·
It is used for water retaining structure like
tanks, reservoir, retaining walls, pool, dam etc.
9. High Alumina
Cement
·
Black chocolate color cement produced by fusing
bauxite and limestone in correct proportion, at high temperature.
·
Resists attack of chemicals, Sulphates, seawater,
frost action and also fire. Useful in chemical plants and furnaces.
·
Ultimate strength is much higher than OPC.
·
Initial setting time is 2 hours, followed soon by
final setting.
·
Most of the heat is emitted in first 10 hrs. Good
for freezing temperatures in cold regions (below 18°C).
·
Develops strength rapidly, useful during wartime
emergency.
·
Unsuitable for mass concrete as it emits large heat
on setting.
10. Portland Slag
Cement
·
Produced by mixing Portland cement clinker, gypsum
and granulated blast furnace slag.
·
Cheaper than OPC, blackish grey in color.
·
Lesser heat of hydration. Initial setting in 1 hr
and final setting 10 hrs.
·
Better resistance to soil agents, sulphates of
alkali metals, alumina, iron and acidic waters.
·
Suitable for marine works, mass concreting.
·
Due to low early strength, not suitable for RCC.
·
OPC with small quantity of air entraining materials
(resins, oils, fats, fatty acids) ground together.
·
Air is entrained in the form of tiny air bubbles
during chemical reaction.
·
Concrete is more plastic, more workable, more
resistant to freezing.
·
Strength of concrete reduces to some degree.
·
Quantity of air entrained should not be more than
5% to prevent excess strength loss.
12. Portland
Pozzolana Cement
·
OPC clinker and Pozzolana (Calcined Clay, Surkhi
and Fly ash) ground together.
·
Properties same as OPC.
·
Produces less heat of hydration and offers great
resistance to attacks of Sulphates and acidic waters.
·
Used in marine works and mass concreting.
·
Ultimate strength is more than OPC but setting
timings are same as OPC.
13. Other Varieties
·
High Alumina Cement
·
Quick Setting Cement
·
Blast Furnace Slag Cement
·
Expanding Cement
·
Hydrophobic Cement
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