This document discusses the key ingredients and properties of reinforced cement concrete (RCC). It describes cement, aggregates, water, and steel reinforcement bars as the main ingredients. Cement acts as the binding agent. Fine and coarse aggregates provide structure and strength. Water enables the chemical reactions during curing. Steel reinforcement bars provide tensile strength to counteract the low tensile strength of concrete. The document also discusses different types of cement used for RCC, including their compositions and purposes. Testing methods for cement such as fineness, setting time, strength, and soundness are also summarized.

1. S.S.A.S.I.T, SURAT GTU

2. INTRODUCTION
CEMENT CONCRETE
The cement concrete may be defined as the
plastic material obtained by mixing of cement, sand,
stone, aggregates and water in suitable proportion
,when placed in forms becomes hard mass after
curing.

3. PLAIN CEMENT CONCRETE
The plain cement concrete has considerable
strength in compression has little strength in
tension. Therefore the use of plain cement concrete
is restricted to situations where high compressive
strength and weight are the primary requirements.

4. The cement concrete used in the
construction of structural members, which are
subjected to high tensile stress by providing
steel reinforcement in the tensile zone of
member before it is concreted. The material
thus obtained is termed as reinforced cement
concrete or R.C.C.
Reinforced Cement Concrete

5. INGREDIENTS OF REINFORCED CEMENT
CONCRETE AND ITS FUNCTIONS
The ingredients of reinforced cement concrete
are:-
1. Cement
2. Sand as fine aggregates
3. Stone aggregates as corse aggregates
4. Water
5. Steel reinforced bars

6. Cement:
Cement is binding material in the cement concrete. This
concrete is used for different engineering works where
strength and durability are of Prime importance.
Functions of cement
1.It fills up voids existing in the fine aggregate and makes
the concrete impermeable.
2.It provides strength to concrete on setting and
hardening.
3.It binds the aggregate into a solid mass by virtue of its
setting and hardening properties when mixed with water.

7. Aggregate:
In the cement concrete, to provide good quality of
concrete aggregate is used in two size groups:
· Fine aggregate (sand) particle size less than 4.75mm
· Coarse aggregate – Particle size more than 4.75mm
Fine aggregate (sand)
Sand consists of small angular or rounded grains of
silica. Sand is commonly used as the fine aggregate in
cement concrete. Both natural and artificial sands are
used for this purpose.

9. Functions of sand:
1. It fills the voids existing in the coarse aggregate.
2. It reduces shrinkage and cracking of concrete.
3. By varying the proportion of sand concrete can be
prepared economically for any required strength.
4. It helps in hardening of cement by allowing the
water through its voids.

10. Coarse aggregate
Functions:
· Coarse aggregate makes solid and hard mass of concrete
with cement and sand.
· It increases the crushing strength of concrete.
· It reduces the cost of concrete, since it occupies major
volume.

12. Water
The water is used in concrete plays an important part in
the mixing, laying compaction setting and hardening of
concrete. The strength of concrete directly depends on the
quantity and quality of water is used in the mix.
Functions:
1. Water is only the ingredient that reacts chemically with
cement and thus setting and hardening takes place.
2. Water acts as a lubricant for the aggregate and makes
the concrete workable.
3. It facilitates the spreading of cement over the fine
aggregate.

13. Steel reinforcement bars
The steel reinforced bars used in reinforced concrete are
mild steel round bars, medium tensile steel, high tensile
steel.
Functions:-
1. The plain concrete is very strong in compression but
its tensile strength is only 1/10 of the strength in
compression. so the steel bars are used to reinforce the
concrete as the steel is equally strong in compression as
well as in tension.

15. 2. Bond between concrete and steel can be improved by
use of deformed bars. The deformed bars are provided with
lungs, or deformations on surface of bars to minimize the
slippage of bars in concrete.

17. CLASSIFAICATION ANDCOMPOSITIONOF CEMENT of
Cement
Depending upon our requirements i.e.
using it at a suitable place, we use different types
of cement.
1. PORTLAND CEMENT
Ordinary Portland cement (OPC)
Portland Pozzolona Cement (PPC)
Rapid Hardening cement
Low Heat Cement
White Cement OR Colored Cement
Sulphate- resisting Portland cement
Water-proof Portland cement
Portland blast-furnace cement

18. 2. SPECIAL CEMENT:-
Quick setting Cement
High Alumina Cement
Calcium chloride cement
Slag cement
Expansive cement

19. COMPOSITION OF PORTLAND CEMENT
a) Argillaceous or silicates of alumina in the form of clays and
shales.
b) Calcareous or calcium carbonate, in the form of limestone,
chalk and marl which is a mixture of clay and calcium carbonate.
• The ingredients are mixed in the proportion of about two parts
of calcareous materials to one part of argillaceous materials and
then crushed and ground in ball mills in a dry state or mixed in
wet state.
• The dry powder or the wet slurry is then burnt in a rotary kiln at
a temperature between 1400 degree C to 1500 degree C. the
clinker obtained from the kiln is first cooled and then passed on to
ball mills where gypsum is added and it is ground to the requisite
fineness according to the class of product.

21. Lime (CaO) 60 to 67%
Silica (SiO2) 17 to 25%
Alumina (Al2O3) 3 to 8%
Iron oxide (Fe2O3) 0.5 to 6%
Magnesia (MgO) 0.1 to 4%
Sulphur trioxide (SO3) 1 to 3%
Soda and/or Potash (Na2O+K2O) 0.5 to 1.3%
Compound Abbreviated designation
Tricalcium silicate (3CaO.SiO2) C3S
Dicalcium silicate (2CaO.SiO2) C2S
Tricalcium aluminate (3CaO.Al2O3) C3A
Tetracalciumaluminoferrite
(4CaO.Al2O3.Fe2O3)
C4AF
The chief chemical constituents of Portland cement are as
follows:
The below constituents forming the raw materials undergo
chemical reactions during burning and fusion, and combine to
form the following compounds called BOGUE COMPOUNDS.

22. Portland Cement Normal Rapid hardening Low heat
(a) Composition:
Percent
Lime 63.1 64.5 60
Silica 20.6 20.7 22.5
Alumina 6.3 5.2 5.2
Iron Oxide 3.6 2.9 4.6
(b) Compound:
Percent
C3S 40 50 25
C2S 30 21 35
C3A 11 9 6
C3A 12 9 14
COMPOSITION AND COMPOUND CONTENT OF
PORTLAND CEMENT

23. Ordinary Portland Cement (OPC) is the most common cement
used in general concrete construction when there is no
exposure to sulphates in the soil or groundwater.
OPC is manufactured under an effective system of testing,
control and monitoring, conforming to requirements under
SIRIM's product Certification License. Lafarge Malaysia's OPC is
sold in bulk.
The bureau of Indian standards has Introduced three different
grades of Ordinary Portland Cements (OPC)
33 Grade (IS 269-1989)
43 Grade (IS 8112-1989)
53 Grade (IS 12269-1987)
ORDINARY PORTLAND CEMENT (OPC)

24. • Pozzolana is a volcanic powder found in Italy near Vesuvius.
• A pozzolanic material is essentially a siliceous or aluminous
material which possess no cementations properties. But it has the
property when it combined with lime to produce a stable
pozzolana compound it has definite cementations properties.
• In the presence of water Pozzolana reacts with calcium
hydroxide, liberated in the hydrogen process at ordinary
temperature to produce compounds possessing cementations
process. By adding the additional pozzolana such as fly ash
calcium hydroxide coverts into calcium silica hydrated gel.
Ca (OH)2 + pozzolana + Water -> C-S-H (gel)
PORTLAND POZZOLANA CEMENT

25. Composition and manufacturing of pozzolana Portland cement
(PPC)
• Pozzolana Portland cement is manufactured by grinding
Portland cement clinker and pozzolana (usually fly ash 10 to 30
% by mass of PPC) or by intimately and uniformly Portland
cement and fine pozzolana.
• As per the latest construction the proportion of pozzolana may
vary from 15 to 35 % by weight of clinker earlier it was 10 to 15
%.
• By adding the fly ash content up to the permissible limits
increases the long term strength ,durability and reduce the
volume changes.

26. RAPID HARDENING PORTLAND CEMENT (RHPC)
Rapid hardening cement is similar to Ordinary Portland cement
but with higher tri-calcium silicate (C3S) content and finer
grinding. It gains strength more quickly than OPC, though the
final strength is only slightly higher. This type of cement is also
called as High-Early Strength Portland Cement. The one-day
strength of this cement is equal to the three-day strength of
OPC with the same water-cement ratio.

27. TYPES OF CEMENT COMPOSITION SITUATUIONS PURPOSES
Sulphate Resisting Cement
SRC is manufactured with
less than 5% calcium
aluminate to withstand
Sulphate attacks
This type of cement is used
where the concrete is
direct contact with soil
(which has high sulphate
content)
1. Pile foundation
2. In Coastal area
Works
3. Sewage and water
treatment plants
Low Heat Cement
This type cement is
produced by lowering the
amount of tri-calcium
aluminate (C3A) & di-
calcium silicate (C2S)
This type of cement is used
in mass constructions (like
dams) and in high wear
resistance required area
1. Mass Construction
(Dams, Marine
constructions)
2. Hydraulic
Engineering Concrete
3. Retaining wall
construction
Quick Setting Cement
This type of cement is
manufactured by reducing
the amount of gypsum and
adding small amount of
aluminiumsulphate to
accelerate setting time of
cement
As the name suggests, it is
used where the works
needs to be done quickly
1. In Underwater
Constructions
2. In Cold and Rainy
weather Conditions
High Alumina Cement
HAC or CAC is produced
from lime stone/Chalk and
Bauxite
This cement is used in
construction of refineries,
factory or other workshop
type structure because
HAC is counter to high
temperature
Used in Sewage
structures and in acidic
structures

28. Colored Cement
Coloured cement is
manufactured by
mixing colour pigments
(5-10 % ) with OPC
As the name suggests, It
is used where coloured
cements required for
any aesthetic purpose
1. Artificial Marble
2. Floor finishing
White Ordinary Portland
Cement
WOPC is same as the
Ordinary Portland
Cement except the color
WOPC used in white
washing purpose for
aesthetic purpose
1. Used as a base
coat before painting
2. Used to cover the
hairline cracks on
concrete surface to
give smooth finish
Blast Furnace Slag Cement
It is obtained by
grinding the clinkers
with about 60% slag
and resembles more or
less in properties of
Portland cement
--------
It can used for
works economic
considerations is
predominant.
Expansive Cement
Expansive Cement is
formed from the
reaction of tri calcium
aluminate (C3A) with
Calcium Sulphate
(C2SO4)
As the name suggests, it
expands and increases
in volume while settled.
Used to avoid the
shrinkage of concrete
1. Used in repair
works
(to create a bond
with old concrete
surface)
2. Used in Hydraulic
Structures

29. TESTING OF PORTLAND CEMENT
1. Fineness test
2. Setting time test
3. Strength test
4. Soundness test
5. Heat of hydration test
6. Chemical composition test

30. Ratio of percentage of lime to percentage of silica, alumina
and iron oxide when calculated by
Cao-0.7So3
—————————————
2.8SiO ₂ +1.2Al ₂ O ₃+0.65Fe ₂ O ₃
Should not be greater than 1.02 and not less than 0.66
This is called LIME SATURATION FACTOR PERCENT
CHEMICAL COMPOSITION TEST

31. • Finer cement offers greater surface area.
• Disadvantage of fine grinding is that it is susceptible to air
set & early deterioration.
• Maximum no. of particles in a sample of
cement<100microns.
• The smallest particle should have a size if 1.5microns.
• Large particle should have a size of 10microns.
FINENESS TEST

32. Fineness of cement is tested in two ways.
• By sieving.
• By determination specific surface by air permeability method.

33. • Take correctly 100grams of
cement on a standard IS sieve No.9
• Break down the air-set lumps &
sieve it &weigh it.
• This weight shall not exceed 10%
for ordinary cement.
• Sieve test is rarely used.
• The weight of the residue
should not exceed 10% for
ordinary cement.
SIEVE TEST

34. An arbitrary division has been made for the setting time of
cement as
 Initial setting time
 Final setting time.
SETTING TIME TEST

35.  The time elapsed between the moment that the water is
added to the cement, to the time that the paste starts losing
its plasticity.
 Normally a minimum of 30min has maintained for
mixing & handling operations.
 It should not be less than 30min.
INITIAL SETTING TIME

36. FINAL SETTING TIME
 The time elapsed between the moment the water is
added to the cement, and the time when the paste has
completely lost its plasticity and has attained sufficient
firmness to resist certain definite pressure.
 It should not exceed 10hours. So that it is avoided from
least vulnerable to damages from external activities.

37. PROCEDURE:
 Vicat apparatus is used for finding the
setting time
 Take 500gms of cement and add
about 0.85p
 The paste should be filled within 3-5
minutes.
 Initial and final setting time is noted.

38. STRENGTH TEST
 This is the most important of all properties of hardened
cement.
 Due to excessive shrinkage and cracking the strength
tests are not made on neat cement paste.
 Standard sand is used for finding the strength of cement.

39.  Take sand and cement (i.e., 1:3 ratio of cement and sand)
Mix them for 1min, then add water of quantity(P/4)+3.0%.
 Mix three ingredients thoroughly until the mixture is of
uniform colour.
 The time of mixing should not be<3min and >4min.Then
the mortar is filled into a cube mould of 7.06cm. Compact the
mortar.
 Keep the compacted cube in the mould at a temperature of
27°C ± 2°C and at least 90 per cent relative humidity for 24
hours.
 After 24hours the cubes are removed & immersed in clean
fresh water until taken for testing.

40. SOUNDNESS TEST
 It is very important that the cement after setting shall not
undergo any appreciable change of volume.
 This test is to ensure that the cement does not show any
subsequent expansions.
 The unsoundness in cement is due to the presence of excess
of lime combined with acidic oxide at the kiln.
 This is due to high proportion of magnesia & calcium
sulphate.
 Therefore magnesia content in cement is limited to 6%.

42. HEAT OF HYDRATION
 This test is applicable only to low heat cement. The
heat of hydration of low heat Portland cement shall
be:-
7 days not more than – 65 calories/gm
28 days not more than – 75 calories/gm

43. Aggregate is the general term applied to those inert
or chemically inactive materials which, when
bonded together by cement, form concrete.
Most of the aggregates used are naturally occurring
aggregates such as crushed rock, gravel and sand.
Artificial and processed aggregates may be broken
brick or crushed air-cooled blast furnace slag.
AGGREGATES

44. FINE AGGREGATES
The material smaller than 4.75mm size is called fine
aggregate. Natural sands are generally used as fine
aggregate.
Sand may be obtained from pits, river, lake or sea-shore.
When obtained from pits, it should be washed to free it
from clean and silt. Sea shore sand may contain chlorides
which may cause efflorescence, and may cause corrosion of
reinforcement. Hence it should be thoroughly washed
before use.
Angular grained sand produces good and strong concrete,
because it has good interlocking property, while round
grained particles of sand do not afford such interlocking.

46. COARSE AGGREGATES
The material retained on 4.75mm sieve is termed as coarse
aggregate. Natural gravels can be quarried from pits where they
have been deposited by alluvial or glacial action and are
normally composed of flint, quartz, schist and igneous rocks.
Coarse aggregates are obtained by crushing various types of
granites, hard lime stone and good quality sand stones.
Coarse grained rocks make hard concrete, and need high
proportion of sand and high water/cement ratio to get
reasonable degree of workability.
Hard and closed-grained crystalline lime stones are very
suitable for aggregate, is cheap, but should be used only in plain
concrete.

47. GRADING OF AGGREGATES
Grading refers to the determination of the particle-size
distribution for aggregate.
Grading limits and maximum aggregate size are
specified because grading and size affect the amount of
aggregate used as well as
cement and water requirements, workability,
durability of concrete.
In general, if the water-cement ratio is chosen
correctly, a wide
range in grading can be used without a major effect on
strength.

48. Sieve Size (mm)
40 mm 20 mm 16 mm 12.5 mm
(Percentage of Passing)
80 100 – – –
63 – – – –
40 95 to 100 100 – –
20 30 to 70 95 to 100 100 100
16 – – 90 to 100 –
12.5 – – – 90 to 100
10 10 to 35 25 to 55 30 to 70 40 to 85
4.75 0 to 5 0 to 10 0 to 10 0 to 10
2.36 – – – –
The grading of coarse aggregate may be varied through wider
limits than that of fine aggregates, since it does not affect the
workability, uniformity and finishing qualities of concrete mix.
As per IS-383 the grading limit of coarse aggregate, both for
single size as well as graded should be as per the table given
below.
Grading Limits For Single-Sized Aggregate of Nominal Size
Grading limits for coarse aggregates

49. Sieve Size
(mm)
63 mm 40 mm 20 mm 16 mm 12.5 mm 10 mm
(Percentage of Passing)
80 100 – – – – –
63 85 to 100 100 – – – –
40 0 to 30 85 to 100 100 – – –
20 0 to 5 0 to 20 85 to 100 100 – –
16 – – – 85 to 100 100 –
12.5 – – – – 85 to 100 100
10 0 to 5 0 to 5 0 to 20 0 to 30 0 to 45 85 to 100
4.75 – – 0 to 5 0 to 5 0 to 10 0 to 20
2.36 – – – – – 0 to 5
Grading Limits For Graded Aggregate of Nominal
Size

50. Sieve Size
Percentage of Passing For
Grading
Zone-I
Grading
Zone-II
Grading
Zone-III
Grading
Zone-IV
10 mm 100 100 100 100
4.75 mm 90 – 100 90 – 100 90 – 100 95 – 100
2.36 mm 60 – 95 75 – 100 85 – 100 95 – 100
1.18 mm 30 – 70 55 – 90 75 – 100 90 – 1000
600 micron 15 – 34 35 – 59 60 – 79 80 – 100
300 micron 5 – 20 8 – 30 12 – 40 15 – 50
150 micron 0 – 10 0 – 10 0 – 10 0 – 15
To describe an aggregate by its maximum and minimum size is
not sufficient. It has to be graded from its minimum to
maximum size. IS-383 recommends the following grading
limit for fine aggregates.
Grading Limits For Fine Aggregates
Grading limits for fine aggregates

52. WATER
Water acts as lubricant for the fine and coarse aggregates and
acts chemically with the cement to form the binding paste for
the aggregate and reinforcement. Water is also used for curing
the concrete after it has been cast into the forms.
Water used for both mixing and curing should be free from
injurious amount of deleterious materials. Portable waters are
generally considered satisfactory for mixing and curing of
concrete.
Less water in the cement paste will yield a stronger, more
durable concrete; more water will give an freer-flowing
concrete with a higher slump. Impure water used to make
concrete can cause problems when setting or in causing
premature failure of the structure.

53. Limit of Solids water
Organic: 200 Mg per liter
Inorganic: 3000. Mg per liter
Sulphate: 400 mg per liter
Chloride: 500 mg per liter for RCC work and 2000 mg per
liter for concrete not containing steel.
Suspended matter: 2000 mg per liter

54. WATER - CEMENT RATIO
Water-Cement ratio is the ratio of volume of water mixed in
concrete to volume of cement used. The strength and workability
of concrete depend to a great extent on the amount of water used.
For a given proportion of the materials, there is an amount of
water which gives the greatest strength.
Amount of water less than this optimum water decreases the
strength and about 10 percent less may be insufficient to ensure
complete setting of cement.
More, than optimum water increases the workability but
decrease the strength. An increase in 10% above the optimum
may decrease the strength approximately by 15% while an
increase in 50% may decrease the strength to one-half.

55. The use of an excessive amount of water not only produces
low strength but increases shrinking, and decreases density
and durability.
According to Abram’s Water-Cement Ratio law, lesser the
water-cement ratio in a workable mix, greater will be its
strength.
According to Powers, cement does not combine chemically
with more than half the quantity of water in the mix. Water-
cement ratio needs to be about 0.25 to complete the hydration
reaction.
Typical values of w/c are between 0.35 and 0.40 because they
give a good amount of workability without sacrificing a lot of
strength.

56. Concrete is known by its grade which is designated as M15,
M20 etc. in which letter M refers to concrete mix and
number 15, 20 denotes the specified compressive strength
(fck) of 150mm cube at 28 days, expressed in N/mm2.
Thus, concrete is known by its compressive strength. M20
and M25 are the most common grades of concrete, and
higher grades of concrete should be used for severe, very
severe and extreme environments.
Grades of concrete

57. The important properties of concrete, which govern
the design of a concrete mix are
Strength
Durability
Workability
PROPERTIES AND TESTS ON FRESH
CONCRETE

58. 1. Strength:
It is one of the most important properties of concrete and
influences many other describable properties of the
hardened concrete.
The mean compressive strength required at a specific age,
usually 28 days, determines the nominal water-cement
ratio of the mix. The other factor affecting the strength of
concrete at a given age and cured at a prescribed
temperature is the degree of compaction.
According to Abraham’s law the strength of fully compacted
concrete is inversely proportional to the water-cement ratio.

59. 2. Durability
The durability of concrete is its resistance to the
aggressive environmental conditions. High strength
concrete is generally more durable than low strength
concrete.
In the situations when the high strength is not
necessary but the conditions of exposure are such
that high durability is vital, the durability
requirement will determine the water-cement ratio
to be used.

60. 3. Workability
It is difficult to properly define and measure the ‘workability’ of
concrete, despite its being the most important property. In its
simplest form, the term ‘workability’ may be defined as the ease
with which concrete may be mixed, handled, transported,
placed in position and compacted.
The degree of workability required depends on three factors.
These are the size of the section to be concreted, the amount of
reinforcement, and the method of compaction to be used.
For the narrow and complicated section with numerous corners
or inaccessible parts, the concrete must have a high workability
so that full compaction can be achieved with a reasonable
amount of effort. This also applies to the embedded steel
sections. The desired workability depends on the compacting
equipment available at the site.

61. The workability of concrete can be measured by
various tests, such as:-
1. Slump test
2. Compaction factor test
3. Vee-bee Test

62. Slump Test
 Apparatus
 Slump cone : frustum of a cone, 300 mm (12 in) of height.
The base is 200 mm (8in) in diameter and it has a smaller
opening at the top of 100 mm
 Scale for measurement,
 Temping rod(steel) 15mm diameter, 60cm length.

63. Slump Test
 Procedure
 The base is placed on a smooth surface and the container is
filled with concrete in three layers, whose workability is to
be tested .
 Each layer is temped 25 times with a standard 16 mm (5/8
in) diameter steel rod, rounded at the end.
 When the mold is completely filled with concrete, the top
surface is struck off (leveled with mold top opening) by
means of screening and rolling motion of the temping rod.
 The mold must be firmly held against its base during the
entire operation so that it could not move due to the
pouring of concrete and this can be done by means of
handles or foot – rests brazed to the mold.

64. Slump Test
 Procedure
 Immediately after filling is completed and the concrete is
leveled, the cone is slowly and carefully lifted vertically, an
unsupported concrete will now slump.
 The decrease in the height of the center of the slumped
concrete is called slump.
 The slump is measured by placing the cone just besides the
slump concrete and the temping rod is placed over the cone
so that it should also come over the area of slumped
concrete.
 The decrease in height of concrete to that of mould is noted
with scale. (usually measured to the nearest 5 mm (1/4 in).

65. Slump Test
 Types Of Slump
The slumped concrete takes various shapes,
and according to the profile of slumped concrete,
the slump is termed as;
Collapse Slump
Shear Slump
True Slump

66. Slump Test
Degree of
workability
Slump (mm) Use for which concrete is suitable
Very low 0 - 25
Very dry mixes; used in road making.
Roads vibrated by power operated
machines
Low 25 - 50
Low workability mixes; used for
foundations with light reinforcement.
Roads vibrated by hand operated
Machines
Medium 50 - 100
Medium workability mixes; manually
compacted flat slabs using crushed
aggregates. Normal reinforced concrete
manually compacted and heavily
reinforced sections with vibrations
High 100 - 175
High workability concrete; for
sections with congested
reinforcement. Not normally suitable
for vibration
Table : Workability, Slump and Compacting Factor of concrete with 19 or 38 mm (3/4
or 11/2 in) maximum size of aggregate.

67. Compacting Factor Test
 Apparatus
Trowels
Hand Scoop (15.2 cm long)
 Rod of steel or other suitable
material
(1.6 cm diameter, 61 cm
long rounded
at one end ).
Balance.

68. Compacting Factor Test
Procedure
1) Ensure the apparatus and associated equipment are clean before test
and free from hardened concrete and superfluous water .
2) Weigh the bottom cylinder to nearest 10gm , put it back on the stand
and cover it up with a pair of floats .
3) Gently fill the upper hopper with the sampled concrete to the level of
the rim with use of a scoop .
4) Immediately open the trap door of the upper hopper and allow the
sampled concrete to fall into the middle hopper .
5) Remove the floats on top of the bottom cylinder and open the trap door
of the middle hopper allowing the sampled concrete to fall into the
bottom cylinder .
6) Remove the surplus concrete above the top of the bottom cylinder by
holding a float in each hand and move towards each other to cut off the
concrete across the top of cylinder

69. Compacting Factor Test
7) Wipe clean the outside of cylinder of concrete and weigh to
nearest 10gm .
8) Subtract the weight of empty cylinder from the weight of
cylinder plus concrete to obtain the weight of partially
compacted concrete .
9) Remove the concrete from the cylinder and refill with
sampled concrete in layers .
10)Compact each layer thoroughly with the standard
Compacting Bar to achieve full compaction .
11)Float off the surplus concrete to top of cylinder and wipe it
clean .
12)Weigh the cylinder to nearest 10gm and subtract the
weight of empty cylinder from the weight of cylinder plus
concrete to obtain the weight of fully compacted concrete .

70. Compacting Factor Test
Workability Slump (mm) C.F Uses
Very Low 0 - 25 0.78 Roads - Pavements
Low 25 - 50 0.85 Foundations Concrete
Medium 25 - 100 0.92 Reinforced Concrete
High 100 - 175 0.95
Reinforced Concrete
(High Reinforcement)

71. VeBe Time Test
 Apparatus
 Cylindrical container with
diameter = 240 mm, and height
= 200 mm
 Mold: the same mold used in
the slump test.
 Disc : A transparent horizontal
disc attached to a rod which
slides vertically
 Vibrating Table : 380*260 mm,
supported by four rubber shock
absorbers
 Tamping Rod
 Stop watch

72. VeBe Time Test
 Procedure
1) Slump test as described earlier is performed, placing the
slump cone inside the sheet metal cylindrical pot of the
consist meter.
2) The glass disc attached to the swivel arm is turn and place
on the top of the concrete in the pot.
3) The electrical vibrator is then switched on and
simultaneously a stop watch started.
4) The vibration is continued till such time as the conical
shape of the concrete disappears and the concrete assume a
cylindrical shape.
5) This can be judge by observing the glass disc from the top
disappearance of transparency.
6) Immediately when the concrete fully assume a cylindrical
shape, the stop watch is switched off.

73. VeBe Time Test
7) The time required for the shape of concrete to change from
slump cone shape to cylindrical shape in second is known
as Vibe Degree.
8) This method is very suitable for very dry concrete whose
slump value cannot be measure by slump test, but the
vibration is too vigorous for concrete with slump greater
than about 50m.
The test fails if VeBe Time is less than 5 seconds .. And the test
must be created when no collapse or shears slump in concrete

74. Precast Cast-in-situ
Elements are manufactured in a controlled
casting environment and have it is easier to
control mix, placement and curing.
Elements are manufactured on site and hence
it is difficult to control mix, placement and
curing.
Quality can be controlled and maintained
easily.
Quality control and maintenance is difficult.
Less labours are required. More labours are required.
Less skilled labours are required. More skilled labours are required.
Precast construction is quick as it can be
installed immediately and there is no waiting
for it to gain strength.
Construction is slow as gaining of strength
requires time.
Increase in strength can be achieved by
accelerated curing.
Increase in strength at situ by accelerated
curing is a difficult task.
Elements can be cast in controlled condition. Elements are cast in open environment.
On site strength test is not required. On site strength test is required.
DIFFERENCE BETWEEN PRECAST & CAST-
IN-SITU CONCRETE

76. Elements can be cast in advance and held until
the hour you need them, thereby saves time.
Elements cannot be casted in advance.
Weather condition has no effect on casting
work.
Weather condition can delay the casting work.
Speedy construction is possible. Speed is less as elements are casted at site.
It is cheaper form of construction if large
structures are to be constructed.
It is cheaper form of construction for small
structures.
Total construction time is less as compared to
cast-in-situ.
Total construction time is more as compared to
precast.
It does not offer a monolithic architectural
character.
It offers a monolithic architectural character.
Elements of varying lengths and shape can be
developed.
There is constraint in length and shape of
element.
Higher maintenance cost. Less maintenance cost.

77. METHODS OF PROPORTIONING CONCRETE
MIXES
The process of relative proportions of cement, sand,
coarse aggregate and water, so as to obtain a concrete of
desired quality is known as the proportioning of
concrete.
The various methods of proporting concrete are as
follows:-
1. Arbitrary method
2. Minimum void method
3. Maximums density method
4. Finess modules method
5. Water cement ratio method

78. M10 1 : 3 : 6
M15 1 : 2 : 4
M20 1 : 1.5 : 3
M25 1 : 1 : 2
(1) Arbitrary Method
The general expression for the proportions of cement, sand and
coarse aggregate is 1 : n : 2n by volume.
1 : 1 : 2 and 1 : 1.2 : 2.4 for very high strength.
1 : 1.5 : 3 and 1 : 2 : 4 for normal works.
1 : 3 : 6 and 1 : 4 : 8 for foundations and mass concrete works.
Recommended Mixes of Concrete
The concrete as per IS 456: 2000, the grades of concrete lower
than M20 are not to be used in RCC work.

79. Type of work
Concrete Mix
Ratio
Max. size of
aggregates (mm)
Water for dry
aggregates (liter)*
Water for
aggregates
condition from
dry to moist batch
(liter)*
Water for best
consistency
(liter)*
Small precast work, fence posts,
poles, garden furniture and other
work of very thin sections
1:2:2 16 20 15 to 16 Soft
Storage tanks, cisterns, sewers, well
knerbs, watertight work, and
columns or other structural parts
subjected to high stresses
1:2:3 20 25 19 to 22 Medium
Reinforced concrete work, floor slab,
beams, columns, arches, stairs etc
1:2.5:3.5 20 32 23 to 27 Medium or soft
Ordinary floors, footpaths, drive
ways, steps, roads, pavements
1:2.5:3.5 20 23 20 to 23 Stiff
Building and basement walls, silos,
sills, lintels, machine foundations
subject to vibration, bridges, dams,
piers, etc exposed to action of water
and frost foundation concrete for
masonry walls
1:2:4 40 30 23 to 26 Stiff or Medium
Culverts, retaining walls, compound
walls, ordinary machine bases, etc.
1:3:5 40 34 26 to 30 Stiff or Medium
Mass concrete for heavy walls, lean
concrete for levelling course of RCC
foundations
1:3:6 63 36 30 to 32 Medium

80. (2) Fineness Modulus Method
The term fineness modulus is used to indicate an index number which
is roughly proportional to the average size of the particle in the entire
quantity of aggregates. The fineness modulus is obtained by adding the
percentage of weight of the material retained on the following sieve and
divided by 100.
The coarser the aggregates, the higher the fineness modulus.
Sieve is adopted for:
All aggregates : 80 mm, 40 mm, 20 mm, 10 mm, and Nos. 480, 240,
120, 60, 30 and 15.
Coarse aggregates : 40 mm, 20 mm, 10 mm, and No. 480.
Fine aggregates : Nos. 480, 240, 120, 60, 30 and 15.
Proportion of the fine aggregate to the combined aggregate by weight
Where, P = desired fineness modulus for a concrete mix of fine and coarse aggregates.
= fineness modulus of fine aggregate
= fineness modulus of coarse aggregate.

81. (3) Minimum Void Method (Does not give satisfactory result)
The quantity of sand used should be such that it completely fills
the voids of coarse aggregate. Similarly, the quantity of cement
used shown such that it fills the voids of sand, so that a dense mix
the minimum voids is obtained.
Then, percentage voids(x) in the aggregate is given by
X= V-V1/V2 *100
V1= volume of water in cylinder
V2= Volume of specimen aggregate added to water
V= volume of mixer
In actual practice, the quantity of fine aggregate used in the mix is
about 10% more than the voids in the coarse aggregate and the
quantity of cement is kept as about 15% more than the voids in the
fine aggregate.

82. 4.) Maximum Density Method: (Not very Popular)
This is an improved method of minimum voids
method developed by Fuller, to get grading of
materials for getting maximum density.
Where, D = maximum size of aggregate (i.e. coarse
aggregate)
P = percentage of material finer than diameter d (by
weight)
d = maximum size of fine aggregate.

83. (5) Water – Cement Ratio Method
According to the water – cement ratio law given by Abram as a
result of many experiments, the strength of well compacted concrete
with good workability is dependent only on the ratio.
The lower water content produces stiff paste having greater binding
property and hence the lowering the water-cement ratio within
certain limits results in the increased strength. Similarly, the higher
water content increases the workability, but lower the strength of
concrete.
Amount of water less than the optimum water decreases the
strength and about 10% less may be insufficient to ensure complete
setting of cement. An increase of 10% above the optimum may
decrease the strength approximately by 15% while an increase in
50% may decrease the strength to one-half.

84. If water cement ratio is less than 0.4 to 0.5, complete hydration
will not be secured.
Some practical values of water cement ratio for structure
reinforced concrete
0.45 for 1 : 1 : 2 concrete
0.5 for 1 : 1.5 : 3 concrete
0.5 to 0.6 for 1 : 2 : 4 concrete.
Concrete vibrated by efficient mechanical vibrators require less
water cement ratio, and hence have more strength.
According to Abram’s Law water-cement law, lesser the water-
cement ratio in a workable mix greater will be the strength.

86. CONCRETE MIX DESIGN
The process of selecting suitable ingredients of
concrete and determining their relative amounts with
the objective of producing a concrete of the required,
strength, durability, and workability as economically as
possible, is termed the concrete mix design.

87. TYPES OF MIXES
1.Nominal Mixes
In the past the specifications for concrete prescribed
the proportions of cement, fine and coarse aggregates.
These mixes of fixed cement-aggregate ratio of
1:n:2n. which ensures adequate strength are termed
nominal mixes.

88. 2. Designed Mixes
In these mixes the basic assumption in design mix
concrete is that the compressive strength of concrete is
dependent on the water-cement ratio.

89. STAGES FOR PRODUCTION OF
CONCRETE
1. BATCHING
2. MIXING
3. TRANSPORTING
4. PLACING
5. COMPACTING
6. CURING

90. Batching:-
Batching is the process of measuring concrete mix ingredients
by either mass or volume and introducing them into the
mixer.
To produce concrete of uniform quality, the ingredients must
be measured accurately for each batch.
 Volume batching
 Weight batching
Volume batching:-
• This method is generally adopted for small jobs .
• Gauge boxes are used for measuring the fine and
coarse aggregate.
• The volume of gauge box is equal to the volume of one
bag of cement.

91.  Gauge bow are also called as FARMAS
 They can be made of timbers or steel.
 They are made generally deep and narrow
 Bottomless gauge boxes are generally avoided.
 While filling the gauge boxes the material should
be filled loosely, no compaction is allowed.

92. Weigh Batching:
•Weigh batching is the correct method of measuring the
materials.
•Use of weight system in batching, facilitates accuracy, flexibility
and simplicity.
•Large weigh batching plants have automatic weighing
equipment.
•On large work sites, the weigh bucket type of weighing
equipment's are used.

93. Mixing
• Thorough mixing of the materials is essential for the
production of uniform concrete.
• The mixing should ensure that the mass becomes
homogeneous, uniform in colour and consistency.
• There are two methods adopted for mixing concrete: (i )
Hand mixing (ii )Machine mixing

94. Hand mixing: Mixing done on a steel plate or on a hard surface manually. Used
when the quantity of concrete needed is in a small quantity. First the sand and
cement taken in correct proportion and mixed in dry state. Then the coarse
aggregate is added and mixed well using shovels. He predetermined amount of
water is added then and mixed till the color is homogeneous and the mix is
workable.

95. Machine mixing: Concrete mixed by means of mechanical mixer. The ingredients are mixed
well in drums. The drums made of steel with the blades in it at an inclined manner. The mixers
are usually electrically operated. The coarse aggregate is fed first then the fine aggregate and
last the cement. The water is added after the aggregate and the cement is thoroughly mixed.
After adding the water the ingredients mixed till a uniform color is achieved [not less than 2
minutes].
Concrete mixers may be of two types:
Batch Mixers
Continuous Mixers
Batch type mixers are employed for work of relatively small magnitude.
Batch type mixers can either be of tilting drum type or closed drum type. In the tilting
drum type, drum rotates about a trunnion axis and is so arranged that it is quiet easy to rotate
and tilt it when it is empty as well as when full.
In the close drum type, the drum remains rotating in one direction and is emptied by
means of the hopper which tilts to receive the discharge.
Continuous mixers are used in mass concreting work where a large and continuous
flow of concrete is required.
In these mixtures, processes of feeding, mixing and emptying go on continuously without
break.

97. TRANSPORTING
Concrete should be handled from the place of mixing to the
place of final deposit as rapidly as practical by methods which
will prevent the segregation or loss of any of the ingredients.
If the segregation does occur during transport, the concrete
should be remixed before being placed.
During hot or cold weather, concrete should be transported in
deep containers, on account of their lower ration of surface area
to mass, reduce the rate of loss of water by evaporating during
hot weather and loss of heat during cold weather.

98. PLACING
Before concrete is placed, it should be ensured that the forms are
rigid, in their correct position, well cleaned and oiled.
Concrete should not be poured into the forms only at one point, but
should be uniformly spread on all the sides for better compaction.
When the work has to be resumed on a surface which has
hardened, such surface should be roughened.
It should then be swept clean, thoroughly wetted and covered with
a 13mm layer of mortar composed of cement and sand in the same
ratio as the cement and sand in the concrete mix.
This 13mm layer of mortar should be freshly mixed and placed
immediately before the placing of the concrete.

99. COMPACTING
The removal of entrapped air during production of concrete and
the uniform, dense arrangement of the constituents of concrete
are effected during the compacting of corners.
Concrete should be thoroughly compacted during the operation
of placing and thoroughly worked around the reinforcement,
around embedded fixtures and into corners of the form work.
Concrete is compacted by vibration.
Vibrators are of four general types:
Internal Vibrators,
External Vibrators,
Surface Vibrators.
Table Vibrators

100. Internal Vibration
It is most commonly used technique of concrete
vibration.
Vibration is achieved due to eccentric weights attached to
the shaft.
The needle diameter varies from 20 mm to 75 mm and
its length varies from 25 cm to 90 cm.
the frequency range adopted is normally 3500 to 5000
rpm.

101. External Vibration
This is adopted where internal vibration can’t be used
due to either thin sections or heavy reinforcement.
External vibration is less effective and it consumes more
power as compared to the internal vibration.
The formwork also has to be made extra strong when
external vibration is used.

102. Table Vibration
It is mainly used for
laboratories where
concrete is put on
the table

103. Surface Vibration
These are also called screed board vibrators.
The action is similar to that of tamping.
The vibrator is placed on screed board and vibration is
given on the surface.
It is mainly used for roof slabs, road pavements etc.,
but it is not effective beyond 15 cm depth.

104. CURING
Curing is one of the most essential operation in which
concrete is kept continuously damp for some days to enable
the concrete to gain more strength.
Curing replenishes the loss of moisture from the concrete due
to evaporation, absorption and heat of reactions.
The period of curing depends upon atmospheric conditions
such as temperature, humidity and wind velocity.
The normal period is between 7 and 10 days.

105. CURING
There are several methods of curing the concrete, the more
common being the following:
Covering the exposed surface with a layer of sacking,
canvas, hessian or similar absorbent materials, and keeping
them continuously wet.
Thoroughly wetting the surface of concrete, and then
keeping it covered with a layer of suitable water proof material,
Curing with the help of steam or hot water, resulting in rapid
development of strength.

106. REINFORCEMENT
Concrete is strong in compression, as the aggregate efficiently
carries the compression load.
It is weak in tension as the cement holding the aggregate in
place can crack, allowing the structure to fail.
Reinforced concrete solves these problems by adding either
steel reinforcing bars, steel fibers, glass fiber, or plastic fiber to
carry tensile loads. Thereafter the concrete is reinforced to
withstand the tensile loads upon it.
For a strong, ductile and durable construction the
reinforcement shall have the following properties:
High strength
High tensile strain
Good bond to the concrete
Thermal compatibility

107. REINFORCEMENT
Steel reinforcement used in reinforced concrete may be of
the following types:
(a)1. Mild steel bars
2. Hot rolled Mild steel deformed bars
(b) 1. Medium tensile steel
2. Hot rolled medium tensile steel deformed bars
(C)1. Hot rolled high yield strength deformed bars.
2. Cold-worked steel high strength deformed bars.
(d) 1. Hard drawn steel wire fabric
2. Rolled steel made from structural steel

108. Sr. .No
Types of nominal size
of bars
Ultimate Tensile
Stress N/mm2
minimum
Yield Stress N/mm2
Elongation
Percent minimum
1.
Mild Steel Grade I or
Grade 60
For bars up to 20mm 410 250 23
For bars above 20mm
up to 50 mm
410 240 23
2.
Mild Steel Grade-II or
Grade 40
For bar up to 20mm 370 225 23
For bars above 20mm
up to 50 mm
370 215 23
3.
Medium Tensile Steel
Grade-75
for bars up to 16mm 540 350 20
for bars above 16 mm
up to 32 mm
540 340 20
for bars above 32 mm
up to 50 mm
510 330 20
Physical Requirement

109. Concrete is good in resisting compression but is very
weak in resisting tension. Hence reinforcement
is provided in the concrete wherever tensile stress is
expected. The best reinforcement is steel, since tensile
strength of steel is quite high and the bond between
steel and concrete is good.
REINFORCED CEMENT CONCRETE

110. Properties of R.C.C./Requirement of Good R.C.C.
1. It should be capable of resisting expected tensile,
compressive, bending and shear forces.
2. There should be proper cover to the reinforcement,
so that the corrosion is prevented.
3. The hair cracks developed should be within the
permissible limit.
5. It is a good fire resistant material.
6. When it is fresh, it can be molded to any desired
shape and size.
7. Durability is very good.
8. R.C.C. structure can be designed to take any load.

111. Uses of R.C.C.
1. R.C.C. is used as a structural element, the common structural
elements in a building where
R.C.C. is used are:
(a) Footings (b) Columns
(c) Beams and lintels (d) Chejjas, roofs and slabs.
(e) Stairs.
2. R.C.C. is used for the construction of storage structures like
(a) Water tanks (b) Dams
3. It is used for the construction of big structures like
(a) Bridges (b) Retaining walls
4. It is used for pre-casting
(a) Railway sleepers (b) Electric poles
5. R.C.C. is used for constructing tall structures like
(a) Multistory buildings (b) Chimneys
(c) Towers.
6. It is used for paving
(a) Roads (b) Airports.