Concrete is a composite material made of coarse and fine aggregates bonded together with a fluid cement that hardens over time. It consists of sand, gravel or crushed stone, cement, water and sometimes admixtures. The cement produces a crystalline structure that binds the aggregates together. Water is needed for the chemical reaction that causes the concrete to harden. Concrete mixers are used to homogenously combine the ingredients. Workability, segregation, bleeding, strength, creep and shrinkage are important properties of both fresh and hardened concrete.

1. Introduction
of
Concrete
Prepared by:
Akshay kumar

2. What is concrete
Concrete is a composite material composed
of aggregate bonded together with a fluid cement
which hardens over time.
Ingredients
- Coarse aggregates
- Fine aggregates
- Cement
- Water
- Admixtures

3. Concrete chain

4. • Large aggregates:
–provide density
(fill space)
–provide strength

5. • Fine aggregates:
– fill small voids between large aggregates
– Increases strength of the cement binder

6. • Cement:
– produces a crystalline structure
– binds aggregates together

7. • Water
– causes chemical reaction to occur
– produces workability

8. Mixing
• A concrete mixer is a device that homogeneously
combines cement, aggregate such as sand or
gravel, and water to form concrete.
• Type of mixtures
1. Pan type
2.Drum type
- Tilting
- Non tilting
- Reversing

9. Pan type concrete mixer

10. Tilting mixer Truck hoist mixer

11. History of concrete
• The time period during which concrete was first
invented depends on how one interprets the term
“concrete.” Ancient materials were crude cements
made by crushing and burning gypsum or limestone.
Lime also refers to crushed, burned limestone. When
sand and water were added to these cements, they
became mortar, which was a plaster-like material used
to adhere stones to each other. Over thousands of
years, these materials were improved upon, combined
with other materials and, ultimately, morphed into
modern concrete.

13. • Today’s concrete is made using Portland cement,
coarse and fine aggregates of stone and sand, and
water. Admixtures are chemicals added to the
concrete mix to control its setting properties and are
used primarily when placing concrete during
environmental extremes, such as high or low
temperatures, windy conditions, etc.

14. Transparent concrete
90-95% normal
concrete
Ingredients
+
5-10% fibers

15. Properties of Concrete
Fresh concrete
1. Workability
2. Segregation
3. Bleeding

16. Hardened Concrete
1. Strength
2. Creep
3. Shrinkage

17. Workability
Effort required to manipulate a concrete mixture
with a minimum of segregation.
• Factors affecting
1. w/c ratio
2. Size of aggregates
3. Shape of aggregates
4. Surface texture of aggregates
5. w/c ratio

18. Test for determination of workability
1. Slump test
2. Compacting factor test
3. Vee Bee test
4. Flow test

19. Slump Test

20. Segregation
Segregation is when the coarese and fine
aggregate , and cement paste, become
seperated .
Segregation may happen when the concrete is
mixed , transported, placed or compacted.

21. Bleeding
• Water rising to the surface.
• Typical of wet mixes.