Introduction to concrete technology. An overview of general properties of concrete, it's making, use & different spec.

1. Properties of Concrete
(CE-202)

2. Lecture no 01

3. Contents
 What is Concrete?
 Advantages of Concrete
 Disadvantages of Concrete
 Concrete Constituents
 Cement
 Aggregate
 Water
 Admixture
 Qualities of good concrete
 Types of Concrete

5. What is Concrete?
 Concrete is a composite material made from
several readily available constituents.
 Is the second most commonly used building
material (after timber).
 Concrete is a composition of binding material,
aggregates and water.
 Concrete is a versatile material that can easily be
mixed to meet a variety of special needs and
formed to virtually any shape.

7. Advantages Of Concrete
As a construction material Concrete has the
following advantages:
1. Concrete can handle the compressive stresses
10 times more than the tension and the most of
loads in our life is compressive.
2. Concrete is a brittle material which gives the
advantage to make a rigid structure.
3. Easy to handle, specially (in cases) where
plants are used that give you ready mix concrete.

8. Advantages Of Concrete
4. Concrete is durable, fire-resistant, economical
and easy to be fabricated on-site.
5. Concrete can be reinforced with other materials
easily.

10. Disadvantages Of Concrete
As a construction material Concrete has the
following disadvantages:
1. Low tensile strength
2. Volume instability
3. Low strength to weight ratio

12. Concrete Constituents
 Cement
 Coarse Aggregate
 Fine Aggregate
 Water
 Admixture

13. Cement
 Cement used in conventional concrete is normally
Portland Cement
 The name is the result of its similarity to limestone
quarried in Portland, England.
 Prime ingredients are limestone and clay.
 Ingredients are crushed, ground, blended and
burned.

14. Cement Composition
 Calcium Oxide (CaO) = 60 – 65%
 Silica (SiO2) = 20 – 25%
 Aluminum Oxide = 4 - 8%
 Ferrous Oxide = 2 – 4 %
 Magnesium Oxide = 1 – 3 %

15. Types of Cement
Depending upon our, we use different types of cement.
 Rapid Hardening or High early strength Cement
 Quick setting Cement
 High Alumina Cement
 Portland Slag Cement
 Low Heat Cement
 Air Entraining Cement
 White Cement
 Colored Cement
 Portland Pozzolona Cement

17. Aggregates
 Occupies 70-80% of the volume
 Strength of concrete is generally independent of
aggregate strength.
 Durability may be affected by aggregate strength
 Should be free from impurities
 More angular aggregates require more cement
paste than rounded aggregates.

18. Aggregates
 Generally two size categories:
 Fine and Coarse
 Gradation is important.
 Maximum size of aggregate is controlled by
opening size between reinforcing bars and forms.
 The larger the aggregate size, the lower the volume
of paste that is required.

20. Water
 Rule of Thumb:
“If you can drink it, you can make concrete with it.”
 Some soluble inorganic salts may retard the setting
and curing.
 Dissolved organic material may retard hydration
and entrain excessive amounts of air.

22. Admixture
 Admixtures are used to enhance a particular
property such as strength, workability, freeze-thaw
durability, time to set, etc…
 Two important admixtures:
(a) Air Entrainment
(b) Calcium Chloride (CaCl2)

24. Qualities Of Good Concrete
 Strength
 Durability
 Density
 Workability
 Water Tightness

26. Types Of Concrete
Apart from conventional concrete, concrete is
classified into various types. A few types are
mentioned below:
1. According to binding material used in concrete.
2. According to design of concrete.
3. According to purpose of concrete.

27. Types Of Concrete
According to binding material used, concrete is
classified into two types.
(1) Cement concrete
(2) Lime concrete.

28. Types Of Concrete
Cement Concrete:
In cement concrete useful proportions of its
ingredients are 1 part cement: 1-8 part sand: 2-16
parts coarse aggregates.
Uses: Cement concrete is commonly used in
buildings and other important engineering works
where strength and durability is of prime
importance.

29. Types Of Concrete
Lime Concrete:
The concrete consisting of lime, fine and coarse
aggregates mixed in a suitable proportions with
water is called lime concrete. In this type,
hydraulic lime is generally used as a binding
material.
Uses: Lime concrete is generally used for the
sake of economy in foundation works, under
floors, over roof and where cement is not cheaply
and easily available in required quantity.

30. Types Of Concrete
According to design of concrete, it is classified into
three types.
1. Plain cement concrete(PCC).
2. Reinforced cement concrete(RCC).
3. Pre-stressed cement concrete.

31. Types Of Concrete
Plain Cement Concrete:
The cement concrete in which no reinforcement
is provided is called plain cement concrete or
mass cement concrete. This type of concrete is
strong in taking compressive stresses but weak in
taking tensile stresses.
Uses: Plain cement concrete is commonly
used in for foundation work and flooring of
buildings.

32. Types Of Concrete
Reinforced Cement Concrete:
The cement concrete in which reinforcement is
embedded for taking tensile stress is called
reinforced cement concrete.
In this type of concrete the steel reinforcement is
to be used generally in the form of round
bars,6mm to 32mm dia.
This concrete is equally strong in taking tensile,
compressive and shear stresses.

33. Types Of Concrete
Usual proportions of ingredients
in a reinforced concrete are 1 part
of cement: 1-2 parts of sand: 2-4
parts of crushed stones or gravel.
Uses: RCC is commonly
used for construction of slabs,
beams, columns, foundation,
precast concrete.

34. Types Of Concrete
Pre-Stressed Cement Concrete:
The cement concrete in which high compressive
stresses are artificially induced before their actual
use is called pre-stressed cement concrete. In this
type of cement concrete, the high compressive
stresses are induced by pre-tensioning the
reinforcement before placing the concrete, and the
reinforcement is released when final setting of the
concrete take place.

35. Types Of Concrete
Uses: This concrete can take
up high tensile and compressive
stresses without development of
cracks. The quantity of
reinforcement can be
considerably reduced by using
this concrete.

36. Types Of Concrete
According to purpose, concrete is classified into
following types.
1. Vacuum Concrete
2. Air Entrained Concrete
3. Light Weight Concrete
4. Heavy Weight Concrete

37. Types Of Concrete
Vacuum Concrete:
The cement concrete from which
entrained air and excess water is
removed after placing it, by suction
with the help of vacuum pump is
called vacuum concrete.
In this concrete the excess water
which is added to increase workability
but not required for the hydration of
cement in concrete is removed by
forming vacuum chamber.

38. Types Of Concrete
Lieght-Weight Concrete:
The concrete prepared by using coke
breeze, cinder or slag as coarse
aggregate is called light weight
concrete. The concrete is light in
weight and posses heat insulating
properties.
Uses: This concrete is used in
making precast structural units, for
partitions and wall lining.

39. Types Of Concrete
Heavy-Weight Concrete:
Heavyweight concrete uses heavy natural
aggregates such as barites or magnetite or
manufactured aggregates such as iron or lead shot.
Uses: The main land-based application is for
radiation shielding (medical or nuclear). Offshore,
heavyweight concrete is used for ballasting for
pipelines and similar structures.

40. Types Of Concrete
The density achieved will depend on the type of
aggregate used. Typically using barites the density
will be in the region of 3,500kg/m3, which is 45%
greater than that of normal concrete, while with
magnetite the density will be 3,900kg/m3, or 60%
greater than normal concrete. Very heavy concretes
can be achieved with iron or lead shot as aggregate,
5,900kg/m3 and 8,900kg/m3 respectively.

42. Water-Cement Ratio
 In the preparation of concrete the water cement
ratio is very important
 For normal construction the water cement ratio is
usually 0.5
 Adding to much water will reduce the strength of
concrete and can cause segregation.

43. Water-Cement Ratio
 For different ratio of concrete the amount of
water for 50kg of cement is
Concrete ratio Water quantity
1:3:6 34 liter
1:2:4 30 liter
1:1.5:3 27 liter
1:1:2 25 liter