Presentation on Concrete......

2. MNS UET MULTAN

3. Sohail Haider
Mushhood ur Rehman
Muhammad Imran Nawaz
Muhammad Saqib Hanif

4. The word “concrete”
originates from the Latin
word “concretus”, which
means to grow together.

5. CONCRETE
Concrete is a composite
material in which a binding
material mixed in water with
well grouped fine and coarse
aggregates.

6. 1891- Concrete Street
The first American concrete street
was built in Bellefontaine, Ohio.
This is a modern photo of the
historic street.

8. Thomas Edison designed and built
the first concrete homes in Union,
New Jersey. These homes still exist
today.

10. The Hoover Dam was built
along the Colorado River,
bordering Arizona and Nevada.
It was the largest scale concrete
project ever completed.

12. The first concrete domed sports
arena, known as the Assembly
Hall, was built at the
University of Illinois.

14. Binding material
Fine aggregate
Coarse aggregate
Water
Admixture.

15. Cement and lime are
generally used as binding
materials.

16. sand ,cinder is used as fine
aggregates .

17. crushed stones, gravel,
broken bricks are used as
coarse aggregates.
Crushed Stones

18. Gravels

19.  Freshly prepared concrete till it
has not yet set is called “wet
concrete”.
 After it has thoroughly set and
fully hardened it is called “set
concrete”.

20.  Generally there are two methods
for mixing the concrete ,
1. Hand mixing
2 . Machine mixing

21. In this type , the mixing is done by
manual labors.
This method is adopted for small
construction works .
Requirement of cement is more
than machine mixing (10%).
Normally the mixing time is about
3 minutes.

22. Construction of platform of bricks , lean
concrete or iron-sheet.
Spread-out sand evenly , spread cement on
it.
Mix it till the color of mixing become
uniform.
Spread this mixture & spread coarse
admixture then mix it.
During mix it remaining water should be
added with continuation process.
Time for mix is generally 2 to 3 minutes.

23. This is similar to hand mixing
only the mixing is carried out in
a rotating drum

24. For machine mixing , all the
ingredients of concrete including
water are collected in a revolving
drum and then the drum is rotated
for a certain period.

25. Ready – mix concrete is type of concrete
that is manufactured in a factory or
batching plant , according to design and
then delivered to a work site , by transit
truck.
It is manufactured under computer-
controlled operations and transported and
placed at the site of constructed.

26. Better quality concrete is
produced.
 storage space for basic materials
at site is not required .
Wastage of basic materials are
avoided.

27. Concrete are classified into different types:
According to
1. Binding material used in
concrete.
2. Design of concrete.
3. Purpose of concrete.

28. CLASSIFICATION ACCORDING TO BINDING
MATERIAL:
1. Cement concrete
2. lime concrete

29. The concrete consisting of
cement, sand and coarse
aggregates mixed in a suitable
proportions in addition to
water is called cement
concrete.

30. In this type of concrete cement is
used as a binding material,
sand as fine aggregates and
gravel, crushed stones as coarse
aggregates.

32. USE:
cement concrete is commonly
used in buildings, roads, dam and
other important engineering works
where strength and durability is of
prime importance.

33. LIME CONCRETE
The concrete consisting of lime,
fine aggregates, and coarse
aggregates mixed in a suitable
proportions with water is called
lime concrete.

34. In this type of concrete hydraulic
lime is generally used as a
binding material, sand and cinder
are used as fine aggregates and
broken bricks, gravel can be used
as coarse aggregates.

35. USES:
1. Lime concrete is generally used for
the sake of economy in foundation
works.
2. Under floors, over roof and where
cement is not cheaply .
3. Easily available in required quantity.

37. PLACING OF LIME CONCRETE :
Placing of concrete shall be
completed within three hours of
adding water in case of concrete is
prepared with hydraulic lime.
Concrete should be well cured for
a period of at least 10 days.

38. CLASSIFICATION ACCORDING TO
DESIGN OF CONCRETE
I. Plain cement concrete(PCC).
II. Reinforced cement
concrete(RCC).
III.Pre-stressed cement concrete.

39. The cement concrete in which no
reinforcement is provided is called
plain cement concrete.
This type of concrete is strong in
taking compressive stresses but
weak in taking tensile stresses.

40. USES:
Plain cement concrete is
commonly used in for
foundation work and flooring
of buildings.

41. REINFORCED CEMENT
CONCRETE(RCC)
The cement concrete in which
reinforcement is embedded for
taking tensile stress is called
reinforced cement concrete.

42. 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.

43. USES:
RCC is commonly used for
construction of slabs, beams,
columns, foundation, precast
concrete.

46. PRE-STRESSED CEMENT
CONCRETE
The cement concrete in which high
compressive stresses are artificially
induced before their actual use is
called pre-stresses cement
concrete.

47. 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.

48. 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.

51.  CLASSIFICATION ACCORDING TO PURPOSE
 According to purpose concrete is classified
into following types.
 a. 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.


52. In this concrete the excess water
which is added to increase
workability but not required for
the hydration of cement of
concrete is removed by forming
vacuum chamber.

54. b. Air entrained concrete
The concrete prepared by mixing
aluminum in it is called air entrained
concrete. In this concrete bubbles of
hydrogen gas are liberated which forms
cell and make the concrete cellular.
USES: This concrete is used for lining
walls and roofs for heat and sound
insulation purpose.

56. c. Light 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.

57. USES:
This concrete is used in
making precast structural units
for partition and wall lining.

58. DESCRIPTION OF WORK GRADE OF
CONCRETE
Concrete in columns, beams 1:1:2
Water retaining structures,
Piles, precast work or dense 1:1.5:3
Concrete.
RCC beams, slabs, columns 1:2:4
Foundations for buildings, 1:3:6
Mass reinforced works.
For mass concrete work. 1:4:8

59. In the preparation of concrete the
water cement ratio is very important
For normal construction the water
cement ratio is usually 0.5 it varries (
0.4 to 0.6).
Adding to much water will reduce the
strength of concrete and can cause
seggregation.

60. Distructive test.
Non distructive test.

61.  Compressive strength test
 Spill tension test

62.  The compressive strength of any material is
defined as the resistance to failure under
the action of compressive forces.
 Test for compressive strength is carried out
either on cube or cylinder. Various standard
codes recommends concrete cylinder or
concrete cube as the standard specimen for
the test. American Society for Testing
Materials ASTM C39/C39M provides
Standard Test Method for Compressive
Strength of Cylindrical Concrete
Specimens.

63. Age Strength per cent
1 day 16%
3 days 40%
7 days 65%
14 days 90%
28 days 99%
 The strength of concrete increases with
age. Table shows the strength of concrete at
different ages in comparison with the
strength at 28 days after casting.

64.  The tensile strength of concrete is one of
the basic and important properties.
Splitting tensile strength test on concrete
cylinder is a method to determine the
tensile strength of concrete.
 Concrete is very weak in tension due its
brittle nature and it is not expect to resist
the tension.

65.  Rebound hammer test
 Penetration resistance test

66.  A instrument Rebound hammer is used to find the
strength the concrete.
 which weighs about 4 lb (1.8 kg) and is suitable for
both laboratory and field work.
 It consists of a spring-controlled hammer mass that
slides on a plunger within a tubular housing.
 The hammer is forced against the surface of the
concrete by the spring and rebound number is
measured on a scale. That reading is called Rebound
number.
Limitations:
The Schmidt hammer provides an inexpensive.
but accuracy of ±15 to ±20 per cent is possible only for
specimens

68. When a probe having a fixed amount of energy is
driven into the concrete, the depth of penetration
depends on the hardness of concrete. For standard
test conditions, the penetration is inversely
proportional to the compressive strength of
concrete but the relation depends on the hardness
of the aggregate.
The probe has a diameter of 0.25” and length
3.125”. The probe is driven into concrete by firing
a powder charge that develops energy of 575 lbs
ft.

70. Slump test is a test conducting before
concrete to
Be used for casting. The purpose of
slump test
Is to determine the water content in
concrete
And its workability

71. 1.Base plate.
2.Trowel to mix concrete.
3.Steel tamping rod.
4.Slump cone.
5.Ruler.

72. Base Plate Trowel to mix concrete
Steel rod Slump cone Ruler

73. STEP 1:
Fill cone 1/3 full by volume and
rod 25 times with 5/8-inch
diameter
x 24-inch-long steel rod.
Distribute rodding evenly over the
entire cross section of the sample.

74. STEP 2:
Fill cone 2/3 full by volume. Rod
this layer 25 times with rod
penetrating into, but not
through first layer. Distribute
rodding evenly over the
entire cross section of the
layer.

75. STEP 3:
Fill the cone to its top level. Rod
this layer 25 times with rod
penetrating into, but not
through second layer. Remove the
excess concrete and level the surface
with a trowel.

76. Clean away the mortar or water leaked
out between the mould and the base
plate.
Raise the mould from the concrete
immediately and slowly in vertical
direction.
Measure the slump as the difference
between the height of the mould and that
of height point of the specimen being
tested.

78. Mass concrete and road work
2.5 to 5cm
Ordinary beams and slam 5 to
10cm
Columns and retaining walls 7.5 to
12.5cm

79. It is the amount of work required to
place concrete and to compact it
thoroughly.
Workability of concrete increases with
the addition of water but it reduces the
strength that’s why it is not a desirable
way of increasing the workability.

80. After mixing of concrete it should
be placed within 30min of adding
of water.
It should be quickly transported to
the place of lying by means of
manually, in wheel barrows, by
pumping .

81. Concrete should not be dropped
from a height as it would cause
segregation of aggregates.
In placing, concrete should be
laid in thin layers. Each layer
being thoroughly compaction,
before the next one is laid.

82. Compaction of concrete is very
important in developing qualities like
strength, durability, imperviousness by
making the concrete dense and free
from voids.
In case of important and big works,
compaction of concrete is done with
vibrator.

83. Use of vibrator is best and the most
efficient way of compacting
concrete. It gives very dense
concrete.
Care should be taken not to make
excessive use of vibrators otherwise
the concrete becomes non
homogeneous.

84. Compaction is a process of expelling
the entrapped air. If we don’t expel
this air, it will result into
honeycombing and reduced strength.
It has been found from the
experimental studies that 1% air in the
concrete approximately reduces the
strength by 6%.

85. Immersion or Needle
Vibrators:
External or Shutter Vibrators
Surface Vibrators
Vibrating Table

86. Vibrating Table Needle Vibrator

87. Needle Liberator Surface Vibrators

88. The process of keeping concrete wet
to enable it to attain full strength is
known as curing.
The objective of curing is to prevent
loss of moisture from concrete due to
evaporation or because of any other
reasons.
Curing should be done for a period of
three weeks but not less then 7 days.

89. To do curing, any one of the following
method can be used.
 The surface of concrete is coated with
a layer of bitumen or similar other
waterproofing compound which gets
into the pores of concrete and prevent
loss of water from concrete.

90.  Concrete surface is covered
with waterproof paper or
with a layer of wet sand. It
could also be covered
bags.

95. STRENGTH:
The concrete should be able to
withstand the stresses that it is
subjected to. It is quite strong in
compression but weak in tension.

96. DURABILITY:
It should be durable enough to resist
the effect of weathering agents.

97. DENSITY:
The concrete should be well
compacted so that there are no voids
or hollows left. It should weigh 3000
kg/cum.

98. WATER TIGHTNESS: when used for
construction of water retaining
structures such as dams, elevated
tanks and water reservoirs then this
property of concrete becomes very
important. Otherwise the moisture
inside the RCC would corrode steel
and leakage would start resulting in
the ultimate failure of the structure.

99. WORKABILITY: It should be easily
workable.
RESISTANCE TO WEAR AND
TEAR: when used in floors and in the
construction of roads the concrete
should be able to withstand abrasive
forces.

100. Concrete, literally, forms the basis our
modern life:
 Roadways/transportation systems
 Airstrips
 Infrastructure (bridges, dams,
buildings)
 Harbor protection (breakwalls)
 Water distribution (pipes & conduit)

101. Advantages of concrete are
 Concrete ingredients are easily
available.
 Concrete can be easily handles and
molded to any desired shape.

102.  Concrete can be easily transported from
the place of mixing to place of casting
before initial set takes place.
 Concrete can be pumped or sprayed to
fill into cracks and lining of tunnels.
 Using steel as reinforcement it is possible
to build any structure; be it lintel or a
massive fly-over.

103.  The monolithic character of concrete
gives it better appearance and much
rigidity to the structure.
 The property of concrete to possess
high compressive strength makes a
concrete structure more economical
than steel structure.

104. The following are the disadvantages of
concrete.
 Concrete have low tensile strength.
Therefore concrete is required to be
reinforced to avoid cracks.
 In long structures, expansion joints are
required to be provided if there is large
temperature variance in the area.

105.  Due to drying shrinkage and moisture
expansion concrete may crack. Therefore
construction joints are provided to avoid
these types of cracks.
 If soluble salt is present in concrete then it
may lead to efflorescence when comes in
contact with moisture.