Cement is a binding material made by burning limestone and clay at high temperatures. It is composed mainly of calcium oxides, silica, aluminum, and iron. There are different types of cement used for various purposes based on setting time and chemical resistance. Cement undergoes hydration when mixed with water, resulting in a chemical reaction that causes it to harden. The setting and hardening process allows cement to be used to bind aggregates like sand and gravel into concrete. Cement is tested for consistency, strength development over time, and other characteristics to ensure it meets specifications.

1. CEMENT
Kardan University
Uploaded BY: Engr.Ahmad Sameer

2. CEMENT
Introduction
Popular as building material.
Material with adhesive & cohesive
properties.
To bind the fine & coarse aggregate
together
To fill voids in between fine & coarse
aggregate particle form a compact mass.

3. COMPOSITION OF CEMENT
• Calcium Oxide (CaO) = 60 – 65%
• Silica (SiO2) = 20 – 25%
• Aluminum Oxide = 4 - 8%
• Ferrous Oxide = 2 – 4 %
• Magnesium Oxide = 1 – 3 %

4. CEMENT
There are 3 kind of mixture/concrete can be created using cement
that are:
Cement Grout
- A mixture of cement & water
Cement Mortar
- A mixture of cement & sand & water to form a paste.
Cement concrete
- A composite product which is obtained by mixing of cement,
water, inert matrix of sand and gravel / crushed stone.

5. CEMENT
PORTLAND CEMENT
Made by mixing substances containing Calcium Carbonate such as chalk /
limestone,
with substances containing silica , alumina and iron oxide such as clay/ shale.
•Clay/shale:
SiO2 Silica (silicon oxide) abbreviated S
Fe203 Ferrite (iron oxide) abbreviated F
Al203 Alumina (aluminium oxide) abbreviated A
•Limestone/chalk
CaC03 Calcium carbonate abbreviated C
•then the mixture heated and became clinker.
•Clinker then grounded to powder.
•The hardening Portland cement is a chemical process during which heat is evolved.
Why is it called "portland" cement?
Joseph Aspdin, an English mason who patented the product in 1824, named it portland
cement because it produced a concrete that resembled the color of the natural limestone
quarried on the Isle of Portland, a peninsula in the English Channel

6. Types of Cement
Depending upon our requirements i.e. using it at a suitable place, we use
different types of cement.
• Rapid Hardening or High early strength Cement
• Quick setting Cement
• High Alumina Cement
• Portland Slag Cement
• Low Heat Cement
• Air Entraining Cement
• White Cement
• Coloured Cement
• Portland Pozzolona Cement

7. Rapid Hardening Cement
This type cement gets the strength faster than OPC, However its
Initial and Final setting is same as those of OPC. It contains more
of Tri-Calcium Silicate and is more finely grounded. It gives out
more Heat while setting so it is as such unsuitable for massive
concrete. It is Used for the Structures which are Subjected to
loads early e.g. Roads, Bridges.
Quick Setting cement
It sets faster than the Ordinary Portland Cement. Its Initial Setting
Time is 5 minutes and the Final Setting Time is not more 30
minutes. It is required for making concrete that is required to set
early as for lying under water or in running water. Initial setting
being very little there is always the danger of concrete having
undergone its initial setting. Thus this type of cement is used in
more special cases.

8. • High Alumina Cement
It is manufactured by the burning of bauxite ore and lime stone in correct
proportions and at high temperature. The resulting product is then ground
finely. It develops Strength Rapidly. It is of black colour and resists well the
attack of chemicals especially of sulphates and sea water. Its ultimate
strength is much higher than OPC. Its initial setting takes more than 2 hours
and the final set takes place immediately thereafter. Most of the heat it gives
in the first 10 hrs as a result it can be conveniently used in freezing
temperatures. At ordinary temperature it is used in thin layers.
• Portland Slag Cement
It is obtained by mixing clinker, gypsum and granulated slag in a proper
proportion. The Properties of this cement is very similar to that of OPC which
are as under. It has lesser heat of hydration and has better resistance of
soils, sulphates of alkali metals, alumina and iron. It has better resistance to
acidic water. This type of cement is mostly used in Marine Works.
• Low Heat Cement
The Heat Generated by cement while setting may cause the structure to
crack in case of concrete. This Heat generation is controlled by keeping the
percentage of Tri-Calcium Silicate and that of Tri-Calcium Aluminate low. Its
initial setting and Final setting times are nearly the same as those of OPC. It
is not very suitable for Ordinary structures because the use of cement will
delayed time of drying. It will also need more curing.

9. • Air Entraining Cement
It is the OPC mixed with some air entraining agents. The
common air entraining agents are oils, fats and fatty acids
etc. These materials have the property of entraining air in
the form of fine air bubbles. The bubbles render the
concrete to become more plastic, workable and more
resistant to freezing. However because of air entrainment
the strength of concrete reduces and as such the quantity
of air so entrained should not exceed 5%.
• White Cement
It is the cement of pure white colour and having same
properties as those of Ordinary Portland Cement. Greyish
colour of cement is due to iron oxide (FeO). White cement
is manufactured from chalk and clay free from Iron Oxide.
Oil fuel and not the coal is used for the burning of this
cement.It is much more costly than ordinary cement. .

10. • Coloured Cement
Various coloured cement are prepared when required in special
cases. Suitable pigments are added with OPC to get red or
brown cement but for other colours 5 – 10% of desired pigments
are grounded with white cement. Pigments used should be
chemically inert and also durable so as they must not fade due to
the effect of lights sun or weather.
• Portland Pozzolona Cement
Portland Pozzolona cement is produced by grinding together
Portland cement and Pozzolona. This cement has properties
similar to those of OPC and can therefore be used for all general
purpose. Portland Pozzolona cement produces less heat of
hydration and offers greater resistance to attack of aggressive
water or sulphates bearing than OPC. Portland Pozzolona
cement are particularly used in marine works. It takes a little
longer to gain strength. Ultimate Strength of this cement is more
than OPC

11. HYDRATION
 It's a process of chemical reaction between
cement and water.
 It results first in setting (the concrete become
solid) and then hardening (increase of
strength and stiffness).
 Heat is liberated during hydration process.
 Thus, during the hardening process, the
concrete is being continually warmed by
internal heat generated

12. WHAT IS SETTING ?
 When cement is mixed with sufficient water, within 1 or 2
hr after the mixing, the sticky paste losses its fluidity ;
within a few hours after mixing, noticeable stiffening
commences.
 Setting can be divided to 2 stage that is:
 a) Initial Set b) Final Set

13.  Initial set is when the paste begin to stiffen
 Final set is when the paste beginning to
harden and able to sustain some loads.
 Initial Setting Time is the time lapse from
the addition of water in the mix to the initial
set.
 Initial Setting Time and Final Setting Time
can be determine by using Vicat Apparatus
in laboratory.
 They are measure at lab. As the time required
for the cement paste to withstand a certain
arbitrary pressure.

14.  The time taken for a 1-mm diameter needle in
the Vicat apparatus to penetrate a depth of
25mm into the cement past sample is the initial
setting time.
 The final setting time is reached when in
the modified Vicat apparatus only the
needle penetrates the surface, while the
attachment fails to do so.
 The rate of setting is also a measure of the
rate of heat of hydration.

15. Test of Cement
•Consistency test
•Compressive strength test
•Tensile strength test

16. VICAT’S APPARATUS

17. VICAT APPARATUS

18. Consistency Test
• It is used to determine the % of water required for
preparing cement pastes for other tests
• Procedure:
1. Take 300g cement, add 30% or 90g of water
2. Mix water and cement on a non-porous surface. Mixing
should be done.
• Fill the mould of Vicat apparatus.
• The interval between the addition of water to the
commencement of filling the moulds is known as the time
of gauging.

20.  Among the factors affect the setting time are:
 a) Fineness of cement
 b) Chemical composition
c) Amount of water
 Gypsum added to clinker to retard setting and
prevent flash set.
 Flash set is defined as the rapid development
of permanent rigidity of the cement paste
along with high heat.
 False set is the rapid development of rigidity
without the evolution of heat .

21. Compressive strength
• Mortar of cement & sand is prepared, 1:3.
• Water is added, water cement ratio 0.4:1
• It is placed in moulds & form cubes of sides 70.6
or 76 mm.
• The cement required is 185 or 235g
• Compacted in vibrating machine in 2 min.
• Moulds placed in damp cabin for 24 hrs
• Specimens are removed & placed in water for
curing.

22. •It is tested in compressive testing
machine after 3 and 7 days.
•Every side is calculated and average
is taken.
•For 3 days: > 115 kg/cm2 or 11.5
N/mm2
•for 7 days: > 175 kg/cm2 or 17.5
N/mm2

23. Tensile Strength
• Procedure:
1. Mortar is prepared cement(1) : Sand (3)
2. Water is added 8%
3. Mortar is placed in briquette moulds

27. • Typical briquette is formed.
• A small heap is formed at its top.
• It is beaten down by a standard spatula till
water appears on the surface.
• Same procedure is repeated for other sides
of briquettes.
• 12 standard briquettes are prepared
• The quantity of cement may be 600g for 12
briquettes

28. • It is kept in damp cabin for 24 hrs.
• It is carefully removed from mould and
submerged in clean water for curing.
• It is tested in testing machine after 3 and 7
days
• The cross section of briquettes at least
section is 6.45 cm2
• Ultimate tensile stress = failing load
6.45

29. • After 3 days: > 20 kg/cm2
• After 7 days: > 25 kg/cm2

30. HARDENING
Hardening is the development of strength over an
extended period of time, is completed for months or
years.
 Hydration is the key for strength development in
concrete.

31.  Hydration process are gradual and require
continuous presence of water.
 Adding water to the cement would cause
temperature of the mixture rise rapidly due to
reaction between Tricalcium Aluminate and
water that is initially quite rapid.
 This is because of since it takes some time
for
the gypsum to dissolve sufficiently to control
the reaction of Tricalcium Aluminate.
 Gypsum prevents flash setting that happen
due
to the reaction of Tricalcium Aluminate.

32.  Thereafter, setting and gradual hardening take
place by the reaction of Tricalcium Silicate
and Dicalcium Silicate with water.
 Atmosphere doesn't take part in hydration
process
 Hydration process can't take place completely
without enough water in the mixture.
 Hydration rate depends surface area of clinker
expose and fineness of grinding.
 Rate of hydration decreases continuously with
age as the resistance to water penetration of
unhydrated cement grains progressively rises.

33. Characteristics of Cement
• Color
• Physical properties
• Presence of lumps
• Strength

34. Colour should be uniform
Typical cement colour (gray colour
with light greenish shade)
It gives an indication of excess of
lime or clay and the degree of
burning.

35. Physical properties
Feel smooth when touched or rubbed in between
fingers.
If felt rough, indicates adulteration with sand.
If hand is inserted in cement bag, hand feels cool
and not warm.
If it immersed in water, it should sink and should
not float
A paste of cement feel sticky
 If it contains clay & silt as adulterant, it give
earthy smell.

36. Presence of Lumps
•It should free from hard lumps.
•It is due to the absorption of moisture
from atmosphere.
•If a bag contains lumps it should be
rejected.

37. Strength
• It is tested by three methods:
1. Briquettes with a lean or weak mortar are made
(75mm x 25mm x 12mm).
The proportion of cement & sand is 1:6.
Immersed in water for 3 days.
• If cement is good it will not be broken easily and difficult to
convert powder form.

38. 2. A block is prepared (25 x 25 x 200) and
immersed in water for 7 days.
• Then it is placed on supports 150 mm
apart and loaded 340N.
• It should not show signs of failure.
3. Thick paste of cement with water is made
on thick glass and kept in water for 24
hours.
• It should set and not crack

39. THE END