TYPES OF CEMENT
TYPES OF
CEMENT
•
Different types
of cement are produced by altering their constituents proportion to gain
required properties for specific purposes.
•
Ordinary Portland
cement (OPC)
•
Rapid Hardening
Portland Cement (RHPC)
•
Low heat Portland
Cement (LHPC)
•
Sulphate
Resisting Portland Cement
•
High alumina
Cement
•
Blast furnace
slag
•
Colored cement
•
Pozzolana cement
•
White cement
Some
generalization
•
As C2S
produces less heat, its content is more in low heat producing cements
•
As C2S
is more resistant to chemical attack, its content is more in cement mostly
exposed to chemical attack
•
As C3S
develops early strength, its content is more in cement like Rapid hardening
cement
•
C3A
more in proportion when quick setting property is required
•
Low heat
producing cements are used in mass concreting
•
Sulphate
resisting cements are used where there is action of sea water
•
These
generalizations will also form the basis of cement classification.
Ordinary
Portland Cement (OPC)
•
It is a common
type of cement
•
It has adequate
resistant to dry shrinkage and cracking
•
It has less
resistant to chemical attack
•
It is not used
for construction work exposed to Sulphate
•
It is
called Portland cement because its color resembles the stone
quarried on the Isle of Portland of the British coast.
Uses of OPC
•
In general
concrete construction when there is no exposure to Sulphate in soil or ground
•
In small
structure where heat of hydration will not cause any defect
Rapid
hardening Portland cement (RHPC)
•
It develops high
early strength as it contains higher percentage of C3S
•
It contains large
proportion of lime; other constituents remaining similar to OPC
•
It is lighter
than Portland cement
•
Its curing period
is small so it is economical
•
It is not used
for massive concrete structures
•
Its strength in 3
days is same as the strength of ordinary Portland cement (OPC) in 7 days
•
It is prepared by
burning at higher temperature than that of OPC
Uses of RHPC
•
It is used where
early strength is desired like-
•
For road pavement
•
For cold weather
concreting
•
Where formwork is
to be removed as early as possible
Low Heat
Portland Cement (LHPC)
•
It contains low percentage
(5%) C3S (more heat producing) and more percentage (46%) C2S
(low heat producing)
•
It contains less
lime than OPC; other constituent remains same as that of OPC
•
It has less
compressive strength
•
It is not used
for thin concrete structures
•
It has little
lower strength than OPC initially but afterwards it attains same strength as
OPC
•
Initial setting
time is 60 minutes
•
Final setting
time is 10 hours i.e. 600 minutes
Uses of LHPC
•
It is used in
mass concreting like for dam, etc. as it produces less heat
•
It is used in
retaining walls
Sulphate Resisting
Portland Cement
•
In this cement,
percentage of C3A is kept below 5% because C3A cannot
resist chemical attack and hence the resulting cement will be more resistant to
chemical attack (Sulphate attack)
•
Uses-
•
It is used in
place exposed to Sulphate attack
•
It is used in
canal, culvert, etc.
High Alumina
Cement
•
It contains about
35% alumina
•
It sets quickly
•
It attains higher
ultimate strength in short period
•
It is completely
resistant to Sulphate
•
It is resistant
to fire
•
It is not
affected by frost
•
Its strength
after 1 day is 40 N/mm2 and after 3 days is 50 N/mm2
Uses of High
Alumina Cement
•
It is used in
chemical plants, furnace, where there is action of sea water
•
It is used in
colder region
•
It is used in
under water construction
•
It is used during
wartime emergency
Blast
furnace slag
•
It is made by
grinding OPC clinker and granulated blast furnace slag
•
It is cheaper
than OPC as it is made from the waste product of furnace
•
Low heat
evolution
•
It is not used in
RCC structures as its early strength is less
•
Uses
•
It is used in
mass concreting as less heat is produced
•
It is used in
dams, bridge abutment, retaining walls
•
It is used in sea
water construction as it has more Sulphate resistant
Colored
cement
•
5-15% coloring
pigment is used before cement is finally ground
•
Also called
colocrete
•
The commercial
name of white and colored cement is “colocrete”, “rainbow cement”, “silvicrete”
•
It is costlier
than OPC
•
Uses
•
For finishing of
floors, external surfaces
•
Artificial
marble, stair tread
•
Texture panel
faces, windows sill slabs, etc.
Pozzolana
cement
•
It is made by
intergrinding OPC clinker and pozzolana
•
Pozzolanic
material added to OPC clinker is about 25%
•
Pozzolana (silica
and alumina in reactive form) is a silicious material containing 80% clay
•
This cement has
higher tensile strength
•
It evolves less
heat during setting
•
It has water
tightness
•
It is resistant
to expansion
•
It is resistant
to chemical attack and action of sea water
Uses of
pozzolana cement
•
It is used in
hydraulic work like-
•
Dams
•
Weir, etc.
•
In sewage work
•
In laying
concrete under water
White cement
•
It is made from raw materials containing very little iron oxide and
manganese oxide
•
China clay is generally used together with chalk or limestone
•
Oil is used as fuel for kiln to avoid contamination by coal ash
•
It is expensive
•
It dries quickly
•
It has super aesthetic values
•
It has high strength
Uses of
white cement
•
For floor finishing, plaster work, ornamental works, etc.
•
In swimming pool, molding sculptures and statues, painting garden
furniture, etc.
•
For ready-made concrete and precast concrete blocks
Quick
setting cement vs rapid hardening cement
Quick setting cement
|
Rapid hardening cement
|
Initial setting time = 5
minutes
|
Initial setting time = 30
minutes
|
Final setting time = 30
minutes
|
Final setting time = 600
minutes
|
It contains higher
percentage of C3A and C4AF which helps in quick setting
action and gypsum is also used in less amount so as to quicken setting
|
It contains higher
percentage of C3S as C3S contributes to early strength
|
It is used for concreting
work under water or running water as they require quick setting
|
It is used in roads,
pavement, precast concrete as they require early strength
|
Summary of
cement type uses
Examples of types of
cement with
Resistant to Sulphate
attack
|
Example of types of
cement with
Low heat of hydration
|
Used to resist sea water
action
|
Used in mass concreting
like dams
|
High alumina cement
|
Blast furnace slag
|
Sulphate resisting Portland
cement
|
Low heat Portland cement
|
Blast furnace slag
|
Pozzolana cement
|
Pozzolana cement
|
Purpose
|
Cement type
|
In chemical plants, furnace
|
High alumina cement
|
In road pavement, cold
weather
|
Rapid hardening cement
|
Under water or running
water
|
Quick setting cement
|
For aesthetic point of view
|
Colored cement, white
cement
|
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