This document discusses concrete, including its composition, manufacturing process, types, properties, and uses. Concrete is a mixture of a binding material like cement or lime, fine aggregates like sand, coarse aggregates like stone, and water. It is made by mixing, placing, and curing the ingredients. Common types include cement concrete, lime concrete, reinforced cement concrete, and pre-stressed concrete. Concrete has advantages like strength, durability, moldability, and cost-effectiveness. As a building material, it is used widely in structures like buildings, dams, bridges, and more.

2. Presented By:Presented By:
Engineer LATIF HYDER WADHOEngineer LATIF HYDER WADHO
Mehran University College of Engg: & Technology KhairpurMehran University College of Engg: & Technology Khairpur
Civil Engineering MaterialsCivil Engineering Materials
11stst
Term 1Term 1stst
Year B.E.CivilYear B.E.Civil

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CONCRETE

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It is a mixture of binding material,
fine aggregates, coarse aggregates
and water in suitable proportions.
Cement and lime are generally used
as binding materials where as sand,
surkhi, etc are used as fine
aggregates and crushed stones,
gravel, broken pieces of bricks, etc
and water free from organic
impurities are used as coarse
aggregates in the manufacturing of
different types of concrete.

5. The required strength of
concrete can be obtained by
careful selection of its
ingredients and their proper
grading, accurate water
measurements and adopting a
good work man ship, proper
mixing, finishing and curing of
concrete during the
construction work.

6. Concrete is a brittle
material, it is strong in
compression but weak in
tension, so to over come
that weakness steel bars
are used in the R.C.C
construction.

7. MANUFACTURING OF CONCRETE:
Following operations are mainly
involved during manufacturing of
Concrete.

8. Mixing:
For preparing concrete well washed fine
aggregates, coarse aggregates and
cement or lime are spread on pucca
platform and then it is mixed thoroughly till
uniformity is achieved. Machine mixing
can be done, if the magnitude of work so
demands.
Only that much concrete should be mixed
which can be laid within two hours. If
cement has been used in the mix then the
concrete should be laid in position within
30 minutes after water has been added to
it.

9. Placing:
Laying and construction of concrete shall
be paced within three hours of adding
water in case of concrete prepared with
lime mortar and within one hour in case
lime cement mortar has been used.
Concrete should be used in layers not
exceeding 15 cm in thickness when
consolidated. Next layer of concrete is laid
only when the previous one has been
thoroughly consolidated and it should not
be dropped from heights as it would result
in segregation of aggregates. If it is to be
laid at a depth then chutes should be
used.

10. Curing:
Concrete shall be well cured for a
period of at least 07 days after its
laying. Curing shall be done by
spreading wet sand or gunny bags etc,
and watering frequently.

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TYPES
OF
CONCRETE

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Different types of concrete are
used depending upon
requirements in different types
of engineering works. Some
well-known types of concrete
are described as under:

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(1) Cement Concrete:
This is the plain concrete prepared by
using Portland cement as the binding
material and the remaining ingredients, as
usual, are the fine aggregates-sand, coarse
aggregates-broken stone, gravel and water.
It is a concrete of high strength. For
common constructional works, the ratio of
cement. Fine aggregates, coarse
aggregates by volume are 1:2:4 or 1:3:6.
For a very high strength this ratio may be
1:11/2 : 3 and for a very ordinary work not
requiring much of strength it may be 1:4:8.

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(2) Lime Concrete:
This is another plain concrete
which is prepared by using lime
as the binding material and the
remaining ingredients such as
fine aggregates may be sand or
surkhi, coarse aggregates may
be broken bricks, broken stone
or gravel and water. It is a
cheap variety of concrete.

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(3) Reinforced Cement Concrete
(R.C.C):
This is the cement concrete further
reinforced by steel commonly known
as R.C.C. The reinforced cement
concrete has several advantages over
plain concrete and structural steel.

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(4) Pre-stressed concrete:
It is that type of concrete in which
steel as well concrete of very high
strength are used, thus it can sustain
excessively high loads.

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Except above mentioned
Concrete types, there are some
other types of concrete such as:
(5) Precast Concrete,
(6) Mass Concrete,
(7) Light Weight Concrete, (light
weight aggregates are used)
(8) Non-fines Concrete (without
coarse aggregates)
(9) Coloured Concrete.

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Uses and advantages of Concrete:
Concrete as a constructional material has
the following advantages:
(1) Concrete is economically used in the
long run as compared to other building
materials.
(2) Concrete possesses a high
compressive strength and also resist well
to weathering effects. When it is properly
prepared its strength is equal to that of a
hard natural stone.

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(3) Green concrete (fresh concrete)
can be easily handed and moulded
in any size and shape according to
demand/specifications. The form
work can be reused a number of
times for similar jobs, resulting in
economy.
(4) It is strong in compression and
has unlimited structural
applications in combination with
reinforcement.

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(5) The concrete is strengthly used in
the construction of foundations,
walls, beams, lintels, roofs of
buildings, air fields, water retaining
structures, dams, bridges, etc.
(6) It is durable and fire resistant and
requires very little maintenance.
(7) Concrete can be evenly spread
on and filled in fine cracks, fissures
for repairing the components of
structures by grouting process.

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PROPERTIES OF CONCRETE IN
PLASTIC STATE:
A freshly mixed concrete must
possess the under mentioned
properties.
(i) Good workability:
Workability of concrete can be
defined as the ease with which it can
be mixed, transported and placed in
position in a homogeneous state.

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(ii) No segregation:
Segregation may be defined as the
separation of coarser materials from
other mass, if the quantity of water
in the mix is more, the larger sized
aggregates will be separated thus
casing segregation, so concrete
should be free from segregation.

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(iii) No bleeding:
Bleeding may be defined as
separation of water or water sand
cement from freshly mixed
concrete. This is caused due to
excess water content in concrete.

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PROPERTIES OF CONCRETE IN HARDENED
STATE:
A hardened concrete must possess the under
mentioned properties:
(i) Adequate Strength:
Strength is defined as the resistance of a
hardened concrete to rupture under different
loadings and is accordingly designated in
different ways, i.e. tensile strength, compressive
strength, flexural strength, etc. A good quality
concrete in hardened state must possess the
desired crushing strength.

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(ii) Durability:
Durability is defined as the period of
time up to which concrete in
hardened state withstands the
weathering effects satisfactorily.
This property is mainly affected by
water cement ratio . A good quality
concrete in hardened state must be
durable.

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(iii) Impermeability:
The impermeability of hardened
concrete may be defined as the
property to resist entry of water. This
property is achieved by using extra
quantity of cement in concrete mix.
A concrete in hardened state must
be impermeable.

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(iv) Elasticity:
As hardened concrete is brittle
material, it is desired that it should
possess adequate elasticity.

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(v) Low shrinkage:
A hardened concrete should
experience least shrinkage. This
property is guided by water cement
ratio. Shrinkage is less if the water
cement ratio is less.
(vi) Least thermal expansion:
A hardened concrete should
possess least coefficient of
expansion.

29. Developed by:Nadeem Asghar 29
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