Concrete ingredients ppt 1ctctctctct.pptx

KNOW THE PROPERTIES OF
INGREDIENTS OF CONCRETE
• 1.1.1 List the ingredients of concrete
• 1.1.2 Identify the grades of cement
• 1.1.3 Identify the grading of fine and coarse aggregate
• 1.1.4 Mention the quality of water as per the BIS
• 1.1.5 Identify the admixtures used in concrete

• The most widely used construction material.
• Second only to water as the most consumed substance on earth.

• Coarse Aggregates: 30 to 50%
•Fine Aggregates: 25 - 30%
• Matrix (paste):
Water: 15 – 20%
Cementitious materials (cement, pozzolans & slag): 7 – 15%)
Air: 1 – 8%
Chemical Admixtures: < 2%
CONSTITUENTS OF CONCRETE

• cement
• water
• Fine aggregate
• Coarse Aggregate

• Cement is the mixture of calcareous, siliceous, argillaceous and other substances.
Cement is used as a binding material in mortar, concrete, etc.
• Cement is a fine powder which sets after a few hours when mixed with water, and then
hardens in a few days into a solid, strong material. Cement is mainly used to bind fine
sand and coarse aggregates together in concrete. Cement is a hydraulic
binder, i.e. it hardens when water is added.
CEMENT

CHEMICAL COMPOSITION OF CEMENT

(1) Mixing and crushing of raw materials
a. Dry process
b. Wet process
(2)Burning
(3)Grinding
MANUFACTURING OF CEMENT

• The raw materials used for the manufacture of Portland cement are
limestone ( provides CaO ) and clay (provides SiO2, Al2O3 and Fe2O3)
which are finely powdered and mixed in the ratio 3 : 1 by mass.
• The mixture is again ground to a fine powder and water is added.
• The finely ground powder called slurry is heated to 1773 k in a rotary
kiln.
• On heating lime, silica, alumina and ferric oxide react togather
and produces a mixture of dicalcium silicate and tricalcium
aluminate called clinker.

• The clinker is cooled and a small amount of gypsum ( 2-5 % ) is added to
it ,
to delay the setting time of cement .
• The mixture off clinker and gypsum
is then ground to a fine powder
which is called cement .
• It is stored in tall structures called
silos .

• The cement is then packed in waterproof bags and sold in markets .
• When cement is mixed with water , it becomes hard over a period of
time. This is called setting of cement .
• Gypsum is often added to Portland cement to prevent early
hardening or ‘’ flash setting ‘’ , allowing a longer working time.

(a) Dry process:
In this process, the raw materials are
changed to powdered form in the
absence of water.
🞇 In this process calcareous material such
as lime stone (calcium carbonate) and
argillaceous material such as clay are
ground separately to fine powder in the
absence of water and then are mixed
together in the desired proportions.
🞇 Water is then added to it for getting
thick paste and then its cakes are
formed, dried and burnt in kilns.
🞇 This process is usually used when raw
materials are very strong and hard.

(b) Wet process:
IN THIS PROCESS, THE RAW MATERIALS ARE
CHANGED TO POWDERED FORM IN THE
PRESENCE OF WATER.
🞇 In this process, raw materials are pulverized
by using a Ball mill, which is a rotary steel
cylinder with hardened steel balls. When
the mill rotates, steel balls pulverize the
raw materials which form slurry (liquid
mixture).
🞇 The slurry is then passed into storage tanks,
where correct proportioning is done.
Proper composition of raw materials can
be ensured by using wet process than dry
process. Corrected slurry is then fed into
rotary kiln for burning.
🞇 This process is generally used when raw materials are
soft because complete mixing is not possible unless
water is added.

(2) BURNING:
🞇 The raw slurry (wet Process) or raw meal (dry process),
obtained by one of wet or dry process is called
charge.
🞇 Charge is introduced into a rotary Kiln. The rotary kiln
consists of a steel cylinder about 150meters long and
4meter diameter and rotates 30 to 60 turns per hour.
🞇 At one end of the cylinder a screw conveyer is
arranged which slowly allows the charge into the
cylinder.
🞇 In the other end of the cylinder, a burner is arranged.
Coal or burning oil is burnt at this end.
🞇 The charge entering the cylinder slowly moves towards
the hot end. At the burning end of the kiln, the
temperature is around 1600 to 1900 degrees
centigrade.
🞇 At this end some chemical reactions takes place
between oxides of calcium , aluminium and silica.
🞇 Mixture of calcium silicates and calcium aluminates is
formed.
🞇 The resultant product consists of grey hard balls called
clinker cement.

THE PERCENTAGE OF IMPORTANT COMPOUND FORMED IN CEMENT
IS GIVEN BELOW:
(bogue's compound of
cement)

(3)
GRINDING:
• Clinker cement is cooled, ground to fine
powder and mixed with 2 to 5 percent
of gypsum (Calcium sulphate Ca SO4) .
(added for controlling the setting time of
cement)
• Finally, fine ground cement is stored in
storage tanks from where it is drawn
for packing.

HYDRATION OF CEMENT
🞇 The chemical reactions that take place between cement
and water is referred as hydration of cement.
🞇 On account of hydration certain products are formed.
These products are important because they have
cementing or adhesive value.
🞇 Out of all cement compounds (bogue's compound of
cement), the strength of cement is contributed mainly by
silicates.
🞇 Silicates react with water and produce a gel called
Calcium Silicate Hydrate or ‘C-S-H’ gel.
🞇 This gel is initially weak and porous, but with the passage
of time it becomes stronger and less porous.

🞇 In the order of reaction with water, C3A is the first to
react with it and imparts setting to the cement paste.
Hence C3A is responsible for setting.
🞇 Strength contribution by C3A is negligible and therefore
can very well be neglected.
🞇 Strength of cement is mainly contributed by silicates i.e.
C3S and C2S.
🞇 In the category of silicates, C3S is quicker in reacting
with water as compared to C2S. Therefore the initial
strength up to 7 days is mainly given by C3S.
🞇 After 7 days when most of C3S has already exhausted,
C2S also start reacting with water. The strength between
7 and 28 days is contributed mainly by C2S and a part
is contributed by C3S

GRADES OF CEMENT
• In actual practice different types of works have different requirements , like
rapid hardening , more strength , resistant against frost or sulphate actions,
etc.
• One type of cement cannot satisfy different requirements.
• Hence different standards are required to satisfy different situations.
• Nowadays Portland cement has become very popular as a bindings materials
for construction work.
• Lime also possesses binding properties but its properties are not standard.
• Portland cement is mostly used for general purpose of construction.
• Selection of proper cement suiting the requirement brings economy.
• But in such case the product has to be reliable so far as its standard and
properties are an concerned.

• In order to provide different standards of cements, Indian standard institute
decided to give different grades to general purpose cement i.e., Portland
cement.
• Accordingly there are three grades of cements.
• Grade 33 , Grade 43 , Grade 53 .
• The figures written after the grades indicates compressive strength of cement
in N/mm^2.
• These grades are printed on every bag of Portland cement.

• Having known these grades we are rest assured about the quality of the Portland
cement.
• Grade 33 cement is used for unimportant work like plaster or floor concrete .
• While 43 grade cement is suitable for general purposes.
• With the development of technology; the cement possessing very fine particles is
now produced. i.e. grade 53 cement .
• Finer the particles more quick will be the chemical reactions which may reduce time of
hardening and gain more strength.
• The selection of a particular grade of Portland depends upon the type of work for which it
is to be used.

The grade 43 and 53 in cement mainly corresponds to the average
Compressive strength attained after 28 days (6724 hours) in mega Pascal (Mpa) of at least
three mortar cubes ( area of face 50 cm squared ) composed
of one part cement , 3 parts of standards and (conforming to IS 650:1966) by Mass and P/4 (
P is the percentage of water required to produce a paste of
standard consistency as per IS standard )+ 3 percentage ( of combined mass
of cement plus sand ) of water , prepared , stored and tested in the manner described in
methods of physical test for hydraulic cement.

AGGREGATE
What size of aggregate should be used?
• The nominal maximum size of coarse aggregate in no case greater than
one-fourth of the minimum thickness of the member, provided that the
concrete can be placed without difficulty so as to surround all
reinforcement thoroughly and fill the comers of the form.
• For heavily reinforced concrete members as in the case of ribs of
main beams, the nominal maximum size of the aggregate should
usually be restricted to 5 mm less than the minimum clear distance
between the main bars or 5 mm less than the minimum cover to the
reinforcement whichever is smaller.

• Generally represent 60 to 75% of the total
volume of concrete  strong influence on
the properties, proportioning, cost and the
performance of the concrete mixtures.
• Generally divided in two groups:
• Fine aggregates: natural or manufactured
sand. Generally, sand particles almost
entirely pass the 4.75mm sieve and are
predominantly retained on the 75µm
sieve.
• Coarse aggregates: natural gravel or
manufactured material. The particles are
predominantly retained on the 4.75mm
sieve.
AGGREGATES

PROPERTIES OF
AGGREGATE
🞇 Inherited Properties
🞇 Chemical and mineral
composition
🞇 Specific gravity
🞇 Hardness
🞇 Strength
🞇 Color etc.
🞇 Acquired properties
🞇 Shape
🞇 Size
🞇 Surface texture
🞇 Water absorption

IMPORTANCE OF ANGULARITY NUMBER
🞇 The normal aggregate which are suitable
for making concrete may have
angularity number anything from 0 to
11.
🞇 Angularity number 0 represents the
most practicable rounded aggregate
🞇 Angularity number 11 indicates the most
angular aggregate that could be used
for making concrete.

Flaky and elongated particles may have adverse effects on
concrete. For instance, flaky and elongated particles tend to
lower the workability of concrete mix which may impair the long-
term durability.
Flakiness Index is It is the percentage by weight of flaky particles
in a sample.
Elongation Index is the percentage by weight of elongated
particles in a sample.

Effort should be made to use minimum
volume of paste in the concrete. It
should just be sufficient to fill the voids
left out by the aggregates.
This can be achieved by using well
graded aggregates so that the voids
are minimum.

Type of Sand
Fine Sand
Medium
Sand
Coarse Sand
Fineness Modulus
Range
2.2 – 2.6
2.6 – 2.9
2.9 – 3.2
WHY TO DETERMINE FINENESS
MODULUS?
•Fineness modulus is generally used to get an idea of how
coarse or fine the aggregate is. More fineness modulus value
indicates that the aggregate is coarser and small value of
fineness modulus indicates that the aggregate is finer.
•Fineness modulus of different type of sand is as per given
below.
•Generally sand having fineness modulus more than 3.2 is not
used for making good concrete.

Fineness Modulus = 246/100 = 2.46

• The grading, the shape and the texture of
aggregates can significantly influence
concrete workability.
• The amount of water required for a target
workability is related to aggregate
properties:
 Nominal maximum size of the
coarse aggregate.
 Shape and texture of particles of
fine and coarse aggregates.
 Grading of coarse aggregate.
SOME PROPERTIES OF AGGREGATES
AFFECTING FRESH CONCRETE PROPERTIES

PROPERTIES OF AGGREGATES AFFECTING
FRESH CONCRETE PROPERTIES
• Angular sand (manufactured sand) can
significantly increase the water demand
and the cement content for a required
workability.
• Very coarse sands and coarse aggregates
can produce harsh, unworkable mixes.
• Changes in grading (or the shape /
texture) of the aggregates can cause
changes in the water demand of
concrete, segregation and affect
uniformity of concrete from batch to
batch

• The shape and grading of the fine
aggregate can have significant effect
on the bleeding and the finishing
properties of concrete the finer the
sand, the lower the bleeding.
• The temperature of aggregates can
strongly impact on the setting time of
the concrete (T° ↑ setting time ).
↓
FRESH CONCRETE PROPERTIES

• For concrete with compressive
strengths
< 20 MPa, the strength ↑ with ↑
maximum size of the coarse aggregate.
• For concrete of higher compressive
strengths, there is an optimum
maximum size fraction for each
strength level. For high-performance
concrete, the maximum coarse
aggregate size is often limited to 10 –
14 mm.
HARDENED CONCRETE PROPERTIES

• Generally,
• The modulus of elasticity of concrete ↑
with
↑ modulus of elasticity of the aggregates;
• With ↑ modulus of elasticity of
the aggregate, the creep of
concrete .
↓
• For similar compressive strength
levels, better flexural strengths are
obtained when using aggregates with
higher angularity and good surface
HARDENED CONCRETE PROPERTIES

Some Aggregat
Properties
e Characteristics Affecting Concrete
Specific gravity
and bulk
density
Mix proportioning calculations and
concrete density
Size and
grading,
particle shape,
surface texture
Workability of fresh concrete,
economy (mixture proportioning),
strength, bleeding, finish-
ability, pumping
Absorption and
surface moistur
Affect the net water content in
concrete  workability, strength
will vary
High absorption could reduce
durability (freezing and thawing)
Cleanness Dirty aggregates  poor fresh and
hardened (aggregate – paste bond)
concrete properties

Aggregate Characteristics Affecting Concrete Properties
Hardness,
toughness and
wear resistance
Affects the mechanical properties
Abrasion resistance of concrete 
function of aggregate type. Hard
aggregates with good micro- and
macrotextures are better (related to
mineralogy).
Soundness Durability, resistance to weathering
Particle
strength and
elasticity
Resistance to abrasion, creep &
shrinkage; the effect is generally
relatively limited for conventional
(normal) strength concrete
Volume
stability
Drying shrinkage  aggregates with
high absorption properties may have
high shrinkage properties on drying
(e.g. sandstone, shale, slate,
greywacke)

REQUIREMENTS OF WATER USED IN CONCRETE
🞇 Water used for mixing and curing shall be clean and
free from injurious amounts of Oils, Acids, Alkalis, Salts,
Sugar, Organic materials
🞇 Potable water is generally considered satisfactory for
mixing concrete
🞇 Mixing and curing with sea water shall not be permitted.
🞇 The pH value shall not be less than 6

mr-pc
2015-09-07 19:28:30
--------------------------------------------
slightly salty, as in river estuaries.
mr-pc
2015-09-07 19:31:54
--------------------------------------------
The measure of suspended matter in,
a w
a
t
e
r sample which contributes to the
reflection of light or cloudiness.

The permissible limits for solids in
water
Solids
Organic
Inorgani
c
Sulphates (SO4)
Chlorides (Cl)
Suspended
matter
Permissible Limits
(Max)
200 mg/lit
3000 mg/lit
500 mg/lit
500 mg/lit
2000 mg/lit
REQUIREMENTS OF WATER USED IN CONCRETE
What if water does not meet the
above
requirements????

Effect of Sea Water
🞇 Salinity of sea water is approximately 3.5%. If
sea water is used, the main concern will be
the corrosion of steel and reduction in
strength.
🞇 In addition, it also accelerates the setting
time of cement, causes efflorescence and
persistent dampness. Therefore use of sea
water should be avoided for concrete works.

HYDRATION
Concrete achieves its strength through
a chemical process called Hydration.
Hydration is a complex process but in
simple terms, is the reaction between
water and the cement in the mix.

WATER/CEMENT RATIO AND STRENGTH
The most important indicator of strength
Lower the w/c ratio, the higher the final concrete
strength Concept was developed by Duff Abrams
A reduction in the water-cement ratio generally results in an increased quality of
concrete, in terms of density, strength, impermeability, reduced shrinkage and creep, etc.

WATER/CEMENT RATIO AND
STRENGTH

(w/c) Ratio 0.40 0.50 0.60 0.70 0.80
Probable Strength(%) 100 87 70 55 44
Factors Low w/c ratio High w/c ratio
Strength High Low
Permeability Low High
Shrinkage Low High
WATER/CEMENT RATIO AND STRENGTH

ADDING EXTRA WATER TO CONCRETE!!!
🞇 Adding more water creates a diluted paste that is weaker
and more susceptible to cracking and shrinkage
🞇 Shrinkage leads to micro-cracks (zones of weakness)
🞇 Once the fresh concrete is placed, excess water is
squeezed out of paste by weight of aggregate and
cement
🞇 The excess water bleeds out onto the surface.
🞇 The micro channels and passages that were created
inside the
concrete to allow that water to flow become weak zones

ADDING EXTRA WATER TO CONCRETE!!!
🞇 This affects the compressive, tensile and
flexural
strengths, the porosity and the shrinkage
🞇 Loss of Inherent good qualities like
Cohesiveness
and Homogeneity
🞇 Harmful to Strength and Durability
🞇 Sowing the seed of Cancer in concrete
It is an Abuse, It is a Criminal act, Un-engineering
----
--------------(M.S.Shetty, Eminent Author)

* Increased strength.
* Lower permeability.
* Increased resistance to weathering.
* Better bond between concrete
and reinforcement.
* Reduced drying shrinkage and
cracking.
* Less volume change from wetting
and drying.
ADVANTAGES OF LOW WATER/CEMENT RATIO

WORKABILITY
🞇 The ease with which freshly mixed concrete can
be transported, placed and finished without
segregation
🞇 Influencing factors
🞇 Size, Shape, Texture and grading of aggregate
🞇 Water Content

ADMIXTUR
E
🞇 It is an optional ingredient of concrete which is
added to modify the properties of fresh as well
as hardened concrete and grout material as
per some specific requirements.
🞇 Addition of admixture may alter workability,
pumping qualities, strength development,
appearance etc. in fresh concrete and
permeability, strength, durability etc. in
hardened concrete.
🞇 Use of chemical admixture is a must for
producing
high grade concrete.

ADMIXTURE
TYPES
Admixtures to enhance workability
🞇 Mineral (Fly ash, Silica fume, GGBFS)
🞇 Chemical
🞇 Air entraining
Chemical and Air-entraining admixtures
are Covered by IS:9301-1999
a) Accelerating admixtures
b) Retarding Admixtures
c) Water-reducing admixtures (plasticizers)
d) Air-entraining admixtures and
e) Super-plasticizing admixtures

WATER-REDUCING ADMIXTURES
🞇 An admixture which either increases workability of freshly
mixed mortar or concrete without increasing water content
or maintains workability with a reduced amount of water
🞇 Role of water reducers is to deflocculate the cement
particles agglomerated together and release the water tied
up in these agglomerations
🞇 Can be categorized according to their active
ingredients
🞇 salts and modifications of hydroxylized carboxylic acids (HC
type)
🞇 salts and modifications of lignosulfonic acids and
🞇 Polymeric materials (PS type)
🞇 Reduces water demand 7-10%
🞇 Example: PolyHeed 997 -BASF, FLOCRETE N-Don
chemicals

AIR-ENTRAINING ADMIXTURES
🞇 Which causes air to be incorporated in the form of
minute bubbles in the concrete or mortar during mixing,
usually to increase workability and resistance to freezing
and thawing and disruptive action of de-icing salts
🞇 Reduces bleeding and segregation of fresh
concrete
🞇 Can be categorized into four groups:
🞇 salts of wood resins
🞇 synthetic detergents
🞇 salts of petroleum acids,
🞇 fatty and resinous acids and their salts
🞇 MB-AE 90-BASF
,Airalon® 3000-Grace

SUPER-PLASTICIZING ADMIXTURES
🞇 Which imparts very high workability or allows a large
decrease in water content for a given workability
🞇 Reduce water content by 12 to 30 percent
🞇 The effect of superplasticizers lasts only 30 to 60
minutes and is followed by a rapid loss in workability
🞇 Superplasticizers are usually added to
concrete at the jobsite
🞇 Example : Glenium-BASF, Supaflo-Don
Chemicals

2. Steam
curing
3.
Curing
Curing
methods
1. Water
curing
compounds
Water curing
•🞇 Sea watershall not be used for curing
• 🞇 Seawatershall not come into contact with concrete members unless it has attained
adequate strength
• 🞇 Exposed surface of concrete shall be kept continuously in a damp or wet condition by ponding or
by covering with a layer of sacks, canvas, Hessian or similar materials and shall be kept
constantly wet for a period of not less than 14 days from the date of placing of concrete.
CURI
NG

STRESS-STRAIN CURVE
CONCRET
E
Ya
sin ,

STRESS—STRAIN CURVE OF
CONCRETE
At first,
As load is applied ,the ratio
between stress-strain is
approximate linear.
Concrete behaves almost as
an elastic material.
If load is
removed,displacement is
recovered virtually.
Eventually,
The curve is no longer linear.
Behaves more and more as
plastic materia.
The shape of stress-strain
curve is mostly depend on
Ya
sin ,

STRESS-STRAIN CURVE OF
CONCRETE
Ya
sin ,

It is interesting to note that although cement
paste and aggregates individually have
linear stress-strain relationships, the
behavior for concrete is non-linear. This is
due to the mismatch and micro cracking
created at the interfacial transition zone.
Ya
sin ,

STRESS-STRAIN
CURVE
STEEL
Ya
sin , Aust

MATERIAL BEHAVIOR IS GENERALLY REPRESENTED BY A
STRESS-STRAIN DIAGRAM, WHICH IS OBTAINED BY
CONDUCTING A TENSILE TEST ON A SPECIMEN OF
MATERIAL.
Ya
sin ,

– STRESS-
STRAIN
RESPONSEIS
LINEAR.
– Slope = Modulus of
Elasticity (Young’s
modulus) = E
Ya
sin ,

– Begins at yield stress Σy
–Slope rapidly decreases
until it is horizontal or
near horizontal
–Large strain increase,
small stress increase
– Strain is permanent
Ya
sin ,

– After undergoing large
deformations, the metal
has changed its
crystalline structure.
– The material has
increased resistance
to applied stress
(it appears to be
“harder”).
Ya
sin ,

– THE MAXIMUM
SUPPORTED STRESS
VALUE IS CALLED THE
ULTIMATE STRESS,
ΣU.
– Loading beyond σu
results in decreased
load supported and
eventually rupture.
Ya
sin ,

MODULUS OF
ELASTICITY
• It is defined as the slope of its stress-strain curve in the elastic deformation level.
• E= Stress/Strain
Ya
sin ,

THE MODULUS OF ELASTICITY OF CONCRETE IS A
FUNCTION OF
modulus of elasticity of the
aggregates.
Ya
sin ,
the cement matrix.
their relative
proportions.

Stress
At Low
At
High
Modulus of
Elasticity
Constant
Decreasin
g
(cracking)
CHARACTERISTICS
Ya
sin ,

CHARACTERISTICS
Elements
Cement harden
paste Aggregates
Concrete Composite
Modulus of
Elasticity
10-30 Gpa
45-85 Gpa
30-50 Gpa
Ya
sin , Aust

Concrete ingredients ppt 1ctctctctct.pptx

Concrete ingredients ppt 1ctctctctct.pptx

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