1. Department of Civil Engineering
Sep 20, 2010
Concrete (CE-107)
By:
Engr. Muhammad Abbas Qureshi
Department of Civil Engineering

2. CE- Properties of Concrete
What is Concrete?.
Concrete is word of Latin derivation ( con – together ) ( crete – to grow ) and its history can be charted from 3000 BC.
It is a composite material that consists essentially of a binding medium (Cement, Lime) within which are embedded particles or fragments of aggregate(Coarse & Fine Aggregates).
Concrete is often looked upon as “man made rock”.
Section cut from Hardened Concrete
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CE Properties of Concrete

3. CE- Properties of Concrete
Concrete Ingredients
Cement /Lime - Binder
Aggregate - sand, gravel, crushed rock
Fine aggregate Sand
Coarse aggregates ----crushed rock
Water
Admixtures - when necessary
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CE Properties of Concrete

4. CE- Properties of Concrete
Cement
A mixture of inorganic materials that sets and develops strength by chemical reaction with water by formation of hydrates and is capable of doing so under water.
Cement Bag
Cement Powder
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CE Properties of Concrete

5. CE- Properties of Concrete
Cement
Binds the aggregates into a solid mass
Imparts strength to concrete
Makes concrete impermeable by filling up voids in fine concrete
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CE Properties of Concrete

6. CE- Properties of Concrete
Aggregates
Granular materials, such as sand, gravel, crushed stone used with cementing medium to form concrete or mortar.
Aggregates act as a relatively inexpensive inert filler, providing stability against volume changes and influencing strength.
Fine Aggregate
Diameter< 4.75mm
Coarse Aggregate
Diameter > 4.75mm
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CE Properties of Concrete

7. CE- Properties of Concrete
Aggregates
Sand
Fills the voids within coarse aggregates
Assists in hardening of cement by allowing water to seep through its voids
Minimizes shrinking and cracking of concrete
Economizes concrete by varying its proportion for strength
Coarse Aggregate
Acts as main filler, forms the main bulk mass
Binding material adheres on its surface
Imparts volumetric stability and durability to concrete
Increases crushing strength, resistance to wear and tear, and water tightness of concrete
Economizes concrete since it is cheaper than cement
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CE Properties of Concrete

8. CE- Properties of Concrete
Water
It reacts with the cement to form binder that hardens and bonds the aggregates together
Lubricates the fresh concrete enabling it to be placed into position and compacted.
Good water is essential for quality concrete.
It should be good enough to drink--free of trash, organic matter and excessive chemicals and/or minerals.
The strength and other properties of concrete are highly dependent on the amount of water and the water-cement ratio.
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CE Properties of Concrete

9. CE- Properties of Concrete
Concrete Ingredients
Admixtures
They are chemicals that can be added to the concrete immediately before or during mixing and significantly change its fresh, early age or hardened state to economic or physical advantage
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CE Properties of Concrete

10. CE- Properties of Concrete
Concrete Ingredients
Admixtures
Retarding agents – delay setting time
Accelerators – set and acquire strength rapidly
Air entraining agents
Water proofing agents – pore filling, water repelling
Pozzolanas – non-cementing, but forms lime compounds which are cementing
Pigments
Workability agents
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CE Properties of Concrete

11. CE- Properties of Concrete
Cement Concrete
Coarse aggregate acts as a filler.
Fine aggregate fills up the voids between the paste and coarse aggregate.
Cement in conjunction with water acts as a binder.
Admixtures aid the mobility of the mixture by regulating the setting environment and time.
(Setting & Hardening)
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CE Properties of Concrete

12. Advantages of Concrete
Concrete is the most widely used construction material in the world.
It has relatively high compressive strength.
It has better resistance to fire than steel, wood etc
It has long service life with low maintenance cost.
In some type of structure such as dams, piers and footing it is most economical structural materials.
It can be cast to take the shape required making it widely used in pre-cast structural components.
It yield rigid member with minimum apparent deflection.
Concrete can be finished to produce surfaces ranging from glass-smooth to coarsely textured, and it can be colored with pigments or painted.
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CE Properties of Concrete

13. Disadvantages of Concrete
It needs mixing, casting and curing all of which affect the final strength of concrete.
The cost of formwork used to cast the concrete is relatively high.
It has very low tensile strength.
It has low compressive strength as compared to steel which lead to large section of structural members.
Minor crack develops in concrete due to shrinkage.
It requires skill labor and supervision from mixing to finishing.
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CE Properties of Concrete

14. CE- Properties of Concrete
History Concrete
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CE Properties of Concrete

15. Qualities of Good Concrete
Fresh Concrete
Workability – easily workable
Volume stability
Hardened Concrete
Strength – compressive and tensile
Durability – wind, rain, frost, temperature, chemicals and salts
Density – 3,000 kg/m³ well compacted
Water tightness – avoid corrosion of inside steel and leakage, seepage in hydraulic structures
Resistance to wear and tear – abrasive action in floors and roads
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CE Properties of Concrete