6. Concrete.pptx work and manufacturing of concrete

Work

1. Concrete

2. Concrete is a composite material composed mainly of cement, water, aggregates (such as sand or gravel), and sometimes additives or admixtures. It is one of the most widely used construction materials in the world due to its strength, durability, and versatility.

3. The process of making concrete involves mixing the cement, water, and aggregates together to form a paste that gradually hardens over time. The cement acts as a binder, holding the aggregates together to form a solid mass.

4. Concrete can be molded into various shapes and sizes to suit different construction needs, making it suitable for a wide range of applications such as building foundations, roads, bridges, dams, and sidewalks. It can also be reinforced with materials like steel bars to increase its strength and resilience, forming what is known as reinforced concrete.

5. Characteristics of good concrete It should have high compressive strength. On hardening, it should exhibit minimum shrinkage. It must be adequately dense. Good concrete should be durable and able to withstand environmental factors such as weathering, abrasion, freeze-thaw cycles, and chemical exposure without significant deterioration over time.

6. Concrete should be resistant to environmental factors. It should have minimum thermal expansion so as to provide good resistance to fire. It should have sufficient impermeability.

7. Uses of concrete Foundations Buildings Roads Airfields Water retaining structures Docks and harbours Dams Bridges Bunkers Silos

8. Classification of concrete According to binding material Cement concrete Lime concrete According to design Plain cement concrete Reinforced cement concrete (R.C.C) Pre-stressed concrete (P.C.C) According to purpose Light-weight concrete Cellular Concrete Sawdust Concrete Vacuum Concrete White and coloured concrete High early stregth concrete No-fines concrete

9. Bulking of Sand The increase in volume in volume of sand due to presence of moisture is termed as bulking of sand.

10. Water-Cement Ratio It is the ratio of water to cement and is expressed as the ratio of the weight or volume of the water to the weight or volume of the cement.

11. Grading of Aggregates Grading of aggregates is art of doing gradation (Particle size distribution) of an aggregate as determined by sieve analysis.

12. Preparation of Plain Cement Concrete Selection, storing and batching of ingredients. Mixing of ingredients. Transportation of concrete. Placing of concrete. Compaction of concrete. Finishing of concrete. Curing of concrete

13. Batching of ingredients It is the process of proper and accurate measurement of all ingredients of concrete.

14. Placing of Concrete It is the process of depositing the concrete in its required position.

15. Compaction of Concrete It is the process of consolidating concrete after placing it in a position.

16. Finishing of Concrete Finishing of concrete refers to the process of refining the surface of freshly poured concrete to achieve a desired appearance, texture, and level of smoothness. Proper finishing is essential for both aesthetic and functional reasons.

17. Curing of Concrete Curing is the process of keeping the concrete moist for some days in order to enable the concrete gain more strength. Minimum curing period is 7 to 14 days.

18. Methods of Curing By ponding This method is employed for flat surfaces. By Sprinkling water. By using gunny bags. By using curing compound or chemicals.

19. Methods of Curing Curing by Using Ponding

20. Methods of Curing Curing by Watering/Sprinkling

21. Methods of Curing Curing by Using Gunny Bags

22. Segregation The separation of all the ingredients of concrete is termed as segregation. Segregation causes honeycombing and decrease in density.

23. Bleeding Separation of water from the concrete is termed is bleeding.