Types of cement

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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
13.Supersulphated Cement
14.Masonry Cement
15.Expansive Cement

1. Ordinary Portland Cement

It is used in general construction works. All other varieties of Cement are derived from this Cement.

•White Cement
◦OPC with pure white color produced with white chalk or clay free from iron oxide.
◦Instead of coal, oil fuel is used for burning.
◦Much more costlier than OPC.

•Colored Cement
◦Suitable pigments used to impart desired color.
◦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. ◦After 24 hours – not less than 160 kg/cm2
◦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. ◦Shuttering required for long duration so cost will increase.
◦Prolonged curing is required.
◦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.

7. Water Repellent Portland Cement
•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.

11. Air Entraining Cement
•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. Supersulphated Cement
•Initially, not less than 70 per cent finely ground blast furnace slag, Calcium Sulphate and a small quantity of ordinary Portland cement or Portland cement clinker.
•It is finer than ordinary Portland cement.
•Its physical and other properties are almost same as are of ordinary Portland cement except the heat of hydration which is considerably lower.
•It is a slag cement and is resistant to majority of chemicals found in construction industry. It is also resistant to Sulphate attack.
•It is used in: ◦Marine Structures.
◦Mass concrete works subjected to aggressive waters.
◦Reinforced concrete pipes in ground water.
◦Concrete construction in Sulphate bearing soils.
◦In factories where concrete is exposed to highly concentrated Sulphates.
◦Construction of concrete sewers carrying industrial effluents.
◦Underside of railway bridges.

•Under tropical conditions, its use is recommended only below 40`C.
•Can be used as a general purpose cement with adequate precautions.
•It should never be used for casting ‘steam cured concrete’ products.

14. Masonry Cement
•Unlike ordinary cement, it is more plastic.
•Made by mixing hydrated lime, crushed stone, granulated slag or highly colloidal clays are mixed with it.
•Addition of above mentioned materials reduces the strength of cement.

15. Expansive or Expanding Cement
•The main difference in this cement is the increase in volume that occurs when it settles.
•Used to neutralize shrinkage of concrete made from ordinary cement so as to eliminate cracks. A small percentage of this cement with concrete will not let it crack. It is specially desirable for hydraulic structures.
•In repair work, it is essential that the new concrete should be tight fitting in the old concrete. This can be done by using this cement

16. Other Varieties
•High Alumina Cement
•Quick Setting Cement
•Blast Furnace Slag Cement
•Hydrophobic Cement
•Oil-well Cement

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