Cement and cement grades

Cement and cement grades

1. Cement and Cement grade s Shri. Gajul Balaprasad Vitthal Mtech (Construction Management)

2. Cement Cement is a powder type material, when mixed with water gets hard and same mixture when mixed with aggregate coarse (sand and aggregate) it becomes a concrete product after curing.

3. Types of cement Depending on the hardening and setting mechanism. That is Hydraulic cement and non hydraulic cement   Ordinary Portland cement (OPC) Portland Pozzolana cement (PPC) Low Heating cement Quick Setting cement White cement Colored cement Rapid Hardening cement Air Entraining cement Sulphate Resisting cement Blast Furnace cement High Alumina cement Hydrophobic cement Expansive cement

4. Cement ingredients Cement

5. Grades of cement The grades of cement means the strength of cement attained after 28days Cement grade 33 means cement tested after 28days it attains strength of 33MPa Cement grade 43 means cement tested after 28days it attains strength of 43MPa Cement grade 53 means cement tested after 28days it attains strength of 53MPa

6. Different Grades of cement

7. Cement grade 33 IS code for cement grade – IS 269 : 1989 This grade of cement is used for general construction under normal environmental condition . As it has low compressive strength and availability of higher grades of cement hence very less demand of OPC 33.

8. Cement grade 43 IS code for cement grade – IS 8112: 1989 OPC 43 is used for general RCC construction where the grade of concrete is up to M30. It is also used for the construction of precast items such as blocks, tiles, asbestos products like sheets and pipes, and for non-structural works such as plastering, flooring, etc.

9. Cement grade 53 IS code for cement grade – IS 12269 : 1987 OPC 53 is used when we need higher strength concrete and very economical cement content. This cement grade is used for specialized works such as prestressed concrete components, precast items such as paving blocks, building blocks , runways, concrete roads, bridges, and other RCC works where the grade of concrete is M25 and above.

10. Mainly used two types of cement OPC ( Ordinary Portland Cement ) PPC ( Portland Pozzolana Cement )

11. OPC (Ordinary Portland cement) Ordinary Portland cement is one of the most widely used type of Cement. In 1824 Joseph Aspdin gave it the name of Portland cement as it is similar in colour and quality found in Portland stone, which is a white grey limestone in island of Portland, Dorset . Portland cement was developed from natural cements made in Britain beginning from the middle of the 18th century. Its name is derived from its similarity to Portland stone.

12. Advantages of OPC cement It has great resistance to cracking and shrinkage but has less resistance to chemical attacks . Initial setting time of OPC is faster than PPC hence it is mainly used in projects where early de-shuttering is recommended . Curing period of OPC is less than PPC hence it reduces cost of curing. Its initial strength is higher than PPC

13. Disadvantages of OPC cement OPC is costlier than PPC. It cannot be used for mass concreting as it has high heat of hydration as compared to PPC . The durability of concrete made using OPC is less than that of the concrete made using PPC . It produces comparatively less cohesive concrete than PPC, hence concrete pumping becomes a little difficult . OPC has lower fineness, hence has higher permeability and as a result it has lower durability .

14. Fly ash Fly ash is a fine powder that is a byproduct of burning pulverized coal in  electricity generating power plants. Fly ash is a pozzolana , a substance containing aluminous and siliceous material that forms cement in the presence of water. When mixed with lime and water, fly ash forms a compound similar to Portland cement.

15. Portland Pozzolana Cement (PPC) Portland Pozzolana Cement is a variation of Ordinary Portland Cement. Pozzolana materials namely fly ash, volcanic ash, are added to the OPC so that it becomes PPC. Pozzolana materials are added to the cement in the ratio of 15% to 35% by weight .

16. Advantages of Portland Pozzolana Cement ( PPC) It is cost effective. That is cost less than Portland cement. Fly ash is a by-product or a waste product hence use of fly ash concrete reduces CO2 and is thus is environmental friendly. It has good cold weather resistance. It is a non-shrinking material. Fly ash concrete has great  workability  as well and allows a  lower water-cement ratio for similar slumps compared to the ordinary concrete. It reduces the problems of cracks, permeability, bleeding etc. It also reduces the heat of hydration.

17. Use of fly ash leads to slower strength gain. Setting time is longer It reduces the resistance to corrosion of steel reinforcement due to alkalinity reduction but it improves the permeability of concrete Disdvantages of Portland Pozzolana Cement (PPC)

18. Conclusion The mix design is of very prime importance before the starting of any concrete work. In mix design of concrete in which cement replacement is shown by fly ash in some percentage. In this case if PPC cement is used which doesn't allow this ( fly ash replacement in some percentage of cement.) replacement. In mass concrete where heat of hydration is more, in that case PPC is generally used like construction of dykes , sewage pipes, dams, etc . PPC is used in various applications of construction industry. PPC is suitable to use in adverse environmental conditions. and is used world wide.

19. They can be promisingly used in the construction of marine structures, masonry mortars and plastering, hydraulic structures. OPC is frequently used for the construction of high-rise buildings, Roads, bridges, flyovers . OPC is commonly used for the construction of residential and industrial buildings. Presently PPC is used widely in replacement of OPC Cement because PPC contains pozzolanic materials which helps to enhance the strength of concrete. PPC is a green material which contributes towards sustainable development. It is cost effective. That is cost less than Portland cement.