Cement

Civil Engineering Materials , Er. Jayant Chaudhary
pg. 1
Table of Contents
UNIT-5 : CEMENT.....................................................................................................................................2
5.1 Introdution........................................................................................................................................2
5.2 Manufacture of Portland Cement....................................................................................................5
5.3 Constituents of Cement.................................................................................................................11
5.4 Clinker Composition...................................................................................................................... 11
5.5 Hydration, Heat of Hydration and gain of strength of cement:..................................................... 12
5.6 Test on Cement.............................................................................................................................16
5.7 Types of Cement...........................................................................................................................17

pg. 2
UNIT-5 : CEMENT
5.1 Introdution
Cement is a powdery binder material with adhesion and cohesion properties, made by calcining
lime and clay, when mixed with water that sets, hardens and adheres to other materials to bind them together.
 Egyptians mostly used cementing materials, obtained by burning gypsum (calcium sulfate
dihydrate, CaSO4⋅ 2H2O) used in the construction of the cities of Harappa and Mohenjadaro.
Fig: Gypsum
 An analysis of mortar from the Great Pyramid showed that it contained 81.5 per cent calcium sulphate
and only 9.5 per cent carbonate.
 The early Greeks and Romans used cementing materials obtained by burning limestones.
Fig: Limestone
 The Greeks and Romans later became aware of the fact that certain volcanic ash and tuff, when mixed
with lime and sand yielded mortar possessing superior strength and better durability in fresh or salt
water. This volcanic tuff or ash mostly siliceous in nature thus acquired the name Pozzolana.
 The Romans, in the absence of natural volcanic ash, used powered tiles or pottery as pozzolana.

pg. 3
Fig: Volcanic Ash

pg. 4
Fig: Volcanic Tuff
 In India. powered brick named surkhi has been used in mortar. The Indian practice of through mixing
and long continued ramming of lime mortar with or without the addition of Surkhi yielded strong and
impervious mortar.

pg. 5
Fig: Surkhi
 It is learnt that the Romans added blood, milk and lard to their mortar and concrete to achieve better
workability. Haemoglobin is a powerful air-entraining agent and plasticizer, which perhaps is yet another
reason for the durability of Roman structures.
 The cementing material made by Romans using lime and natural or artificial Pozzolana retained its
position as the chief building material for all work, particularly, for hydraulic construction.
 Modern cement, Joseph Aspdin: Invented Portland Cement in U.K. in 1824. He used a mixture of
limestone, clay and water. This mixture was heated at high temperatures. On 21st oct, 1824 was
granted a patent.
Fig: Portland Stone
5.2 Manufacture of Portland Cement
The raw materials required for manufacture of Portland cement are calcareous materials, such as limestone or
chalk, and argillaceous material such as shale or clay.
The process of manufacture of cement consists of grinding the raw materials, mixing them intimately in certain
proportions depending upon their purity and composition and burning them in a kiln at a temperature of about
1300 to 1500°C, at which temperature, the material sinters and partially fuses to form nodular shaped clinker.
The clinker is cooled and ground to fine powder with addition of about 3 to 5% of gypsum in order to increase
setting time. Fly Ash (1%) is also used as an admixture these days to improve workability but does not affect the
strength. The product formed by using this procedure is Portland cement.

pg. 6
Types of Materials
Calcareous (CaO) Argillaceous (Al2O3) Siliceous (SiO2)
Limestone Shale Sandstone
Chalk Clay Silica
Marine Shells Cement Rock
Cement Rock Chalk
Blast Furnace Slag
Marl
Basic constituents of all the materials on and inside earth's surface are : -
Lime, Silica, Alumina, Iron Oxide, Magnesia, etc.
Raw Material
Extraction &
Storage
Correction of
Proportions
Pulverization
(Powdery Form)
in Ball Mill
Pulverize Clinker
and add Gypsum
Formation of
Clinker and Its
Cooling
Calcination in Kiln
(Heating)-enables
fusion
Storage and
Packing

pg. 7
Wet and Dry Process
There are two processes known as “wet” and “dry” processes depending upon whether the mixing and
grinding of raw materials is in wet or dry conditions. With a little change in the above process we have the
semi-dry process also where the raw materials are ground dry and then mixed with about 10-14 per cent
of water and further burnt to clinkering temperature.
Wet Process
 Limestone collected from quarries should first crush to smaller fragments.
 Crushed materials are fed to ball or tube mill- mixed with clay with addition of little water –
slurry (35-50% water) - Corrected slurry (tested for chemical composition) is then fed to rotary
kiln.
 Rotary kiln has the diameter of about 3-8 m and length of 30-200m lined with refractory
material.
 Slurry moves on hot chains and losses moisture called flakes and then subjecting to move
up and down and Fusing process takes place at temperature of about 1400-1500°C.
During this process about 20-30% material gets fused and lime, silica and alumina get
recombined.
 The fused mass turns to nodular form of size about 3-20 mm known as clinker and collected
in SILOS and weighs 1100-1300 gm/lt.
 Clinker is cooled and Gypsum- 2-3% (CaSO4.2H2O) is added to prevent from flash-
setting of cement- increase initial setting time.
 The ball mill and tube mill contain several compartments and produce defined fineness of
cement.
 The material is then fed to packing unit.

pg. 8
 Coal/fuel required is about 350 Kg for 1-ton production.
Dry Process
a. Treatment of raw materials: Crushing, drying, grinding, proportioning and blending (mixing) of
Lime stone and clay.
 Breaking of raw material to 6-14 mm using crushers.
 Rotary drying kiln is used to dry the crushed materials.
 Grinding is done in two stages as ball mill and tube mills and stored in SILOS.
 Proportioning and blending the raw materials in different stages with adding low quantity
of water-12%.
b. Burning or Calcinations: Well-proportioned powdered mixture is charged into rotary kiln.
The greenish black colored glass like lusture material called clinker is prepared in this stage.
During this process up to 400°C dehydration (loss of water) takes place initially. Then
dissociation(the action of disconnecting) of Ca & Mg carbonates proceeds up to 800°C to
900°C and then C2S, C3S, C3A, C4AF compound formed up to 1300°C to1400°C -Clinker.
c. Grinding of the Clinker: Calcined hot clinker is first fed into cooling chamber and then
Gypsum is added and mixture is pulverized. Then grinding is done in two stage as coarser grinding
and finer grinding.

pg. 9
d. Packing and storage of cement: Placed first into concrete storage tanks-SILOS and packed
into high density polyethylene bags, jute and packing cloths of 50 Kg capacity. Coal/Fuel
consumption is about 120 Kg for 1-ton production.
 It is important to note that the strength properties of cement are considerably
influenced by the cooling rate of clinker.

pg. 10
Difference between Dry and Wet Process of manufacturing of cement
S.N. Dry Process Wet Process
1
In this process calcareous material such as
limestone (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. A
quantity of water about 12 per cent by weight
is then added to make the blended meal into
pellets.
In this process, raw materials are pulverized
by using a ball mill. 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. Corrected
slurry is then fed into rotary kiln for burning.
Proper composition of raw materials can be
ensured by using wet process than dry
process
2
In this process, mixing and grinding of raw
materials is done in dry state only.
In this process, mixing and grinding of raw
materials is done by adding 30-50% water
in it.
3
This process is usually used when raw
materials are very strong and hard.
This process is usually used when raw
materials are soft because complete mixing
is not possible unless water is added.
4
The heating is done at 1300°C to 1400°C in
kiln.
The heating is done at 1400°C to 1500°C in
kiln.
5
Less fuel requirements in kiln. The total
consumption of coal in this method is only
about 100 kg when compared to the
requirement of about 350 kg for producing a
ton of cement in the wet process.
High fuel requirements in kiln-fuel needed to
evapourate 30% plus slurry water hence, it
is costlier than dry process
6
Partly rounded burnt product i.e. clinkers
forms.
Elongated burnt product forms after burnt.
7
No control on manufacturing hence more
wastage may takes place.
Fully controlled manufacturing give
minimum wastage of materials.
8
if we consider fuel consumption and time of
process then dry process is better.
If we consider the quality and rate then wet
process is better
9 Almost, 74% of cement is produced. Almost, 26% of cement is produced.

pg. 11
5.3 Constituents of Cement
Constituents/Ingredients of Cement and Their Role
S.N. Constituents Functions Average Composition
1 Lime (CaO)
Control Strength & Soundness. If Lime
decreases, Strength & setting time
decreases.
60-65 (63%)
2 Silica (SiO2)
Gives strength. If Increase, it increases
slow setting.
17-25 (20%)
3 Alumina (Al2O3)
Responsible for quick setting, if in excess
it lowers the strength
3-8 (6%)
4 Iron Oxide (Fe2O3)
Gives colour & helps in fusion of different
ingredients. Renders the highly siliceous
materials easier to burn. If in excess, a
hard clinker, difficult to ground.
0.5-6 (3%)
5 Magnesia (MgO)
Imparts colour & hardness. If in excess,
causes cracks in mortar & concrete and
leads to unsoundness
0.5-4 (2%)
6
Soda+Potash
(Na2O/K2O+H2O),
Alkalies
Residues, causes efflorescence and
cracking.
0.5-1 (1%)
7
Sulphur Trioxide
(SO3)
Makes cement unsound 1-2 (1.5%)
5.4 Clinker Composition
When Raw Materials fuses in Kiln, the resultant compounds produced are Boque compound
For high strength development proper cooling : - 1200°C (15min) - 500°C (10min) - Ambient
Temperature
S.N. Principal mineral compounds Formula Name Symbol
1 Tricalcium silicate 3CaO.SiO2 Alite C3S
2 Dicalcium silicate 2CaO.SiO2 Belite C2S
3 Tricalcium aluminate 3CaO.Al2O3 Celite C3A
4 Tetra calcium alumino ferrite 3CaO.Al2O3.Fe2O3 Felite C4AF
Besides these major compounds, alkaies (Soda & Potash), Calcium sulphate (gypsum) are also
present
1. Tricalcium silicate, C3S - 25-50% (Average = 40%)
 It provides best cementing property, Very good binding quality and its formed when cement is
well burnt.
 It provides early strength and is responsible for 7 days strength.
 The strength of cement in first 28 days is due to C3S.
 It enables clinker easy to grind & increase resistance to freezing and thawing.

pg. 12
 Generates high heat of hydration and increase solubility of cement in water.
 High heat of hydration = 500 J/gm
2. Dicalcium silicate, C2S - 25-40% (average = 32%)
 It hydrates and hardens slowly and takes long time to add to strength that is later strength.
(ultimate strength)
 It enables clinker hard to grind & decrease resistance to freezing and thawing.
 Generates low heat of hydration and decreases solubility of cement in water.
 It imparts chemical resistance.
3. Tricalcium aluminate, C3A - 5-11% (average = 10.5%)
 It reacts immediately with water and is responsible for flash set (initial set).
 It is the first compound to react with water.
 The rapidity of action is regulated by the addition of 2-3% of gypsum at the time of grinding
cement.
 It decreases setting time, hence increased shrinkage and cracking
 it weakens resistance to sulphate attack.
 Volume change increase and hence cracking.
 High heat of hydration increase and lowers ultimate strength.
4. Tetra calcium alumino ferrite, C4AF - 8-14% (average = 9%)
 Responsible for flash set but generates less heat
 Poorest cementing value.
 If increases, it decreases strength
 The hydrates of C4AF show a comparatively higher resistance to the attack of sulphates than
the hydrates of calcium aluminate, C3A.
High Percentage of C3S and low C2S result:
 Rapid hardening
 High early strength and high heat generation
 Less resistance to chemical attack
Low Percentage of C3S and high C2S
result:
 Slow hardening
 Much more ultimate strength with less heat generation
 Greater resistance to chemical attack
5.5 Hydration, Heat of Hydration and gain of strength of cement:
Hydration of Cement
 Anhydrous cement does not bind fine and coarse aggregate. It acquires adhesive property
only when mixed with water. The chemical reactions that take place between cement and
water is referred as hydration of cement.
 The quality, quantity,continuity, stability and the rate of formation of the hydration products
are important.

pg. 13
 The hydration of cement can be visualised in two ways. The first is “through solution”
mechanism. In this the cement compounds dissolve to produce a supersaturated solution
from which different hydrated products get precipitated. The second possibility is that water
attacks cement compounds in the solid state converting the compounds into hydrated
products starting from the surface and proceeding to the interior of the compounds with time. It
is probable that both “through solution” and “solid state” types of mechanism may occur during
the course of reactions between cement and water.
 When water is added to cement, each of the compounds undergoes hydration and
contributes to the final concrete product. Only the calcium silicates contribute to strength.
Tricalcium silicate is responsible for most of the early strength (first 7 days). Dicalcium silicate,
which reacts more slowly, contributes only to the ultimate strength at later times.
 The product C–S–H (C3S2H3) gel represents the calcium silicate hydrate also known as
tobermorite gel which is the gel structure. The C–S–H phase makes up 50–60% of the
volume of solids in a completely hyderated Portland cement paste and is, therefore, the
most important in determining the properties of the paste.
 The gel must be saturated with water if hydration is to continue. The calcium hydroxide
crystals formed in the process dissolve in water providing hydroxyl (OH–) ions, which are
important for the protection of reinforcement in concrete. As hydration proceeds, the two
crystal types become more heavily interlocked increasing the strength, though the main
cementing action is provided by the gel which occupies two-thirds of the total mass of
hydrate.
 The Ca(OH)2 liberated during the silicate phase crystallizes in the available free space.
The calcium hydroxide crystals also known as portlandite consists of 20-25% volume of
the solids in the hydrated paste. The lack of durability of concrete, is on account of the
presence of calcium hydroxide. The calcium hydroxide also reacts with sulphates present in
soils or water to form calcium sulphate which further reacts with C3A and cause deterioration
of concrete. This is known as sulphate attack. To reduce the quantity of Ca(OH)2 in
concrete and to overcome its bad effects by converting it into cementitious product
is an advancement in concrete technology. The use of blending materials such as fly
ash, silica fume and such other pozzolanic materials are the steps to overcome bad
effect of Ca(OH)2 in concrete. The only advantage is that Ca(OH)2, being alkaline in nature
maintain pH value around 13 in the concrete which resists the corrosion of reinforcements.
 It has been found that hydration of C3S produces lesser calcium silicate hydrate and
more Ca(OH)2 as compared to the hydration of C2S. Since Ca(OH)2 is soluble in water
and leaches out making the concrete porous, particularly in hydraulic structures, a
cement with small percentage of C3S and more C2S is recommended for use in
hydraulic structures.
 The tricalcium aluminate Hydrate, C3Ah6 to tricalcium silicate accelerated the hydration
process, reduced setting time and improved the compressive strength.
 It is particularly important to note that the setting (the change of cement paste from
plastic to stiff solid state) and hardening (gain of strength with hydration) is a

pg. 14
chemical reaction, wherein water plays an important role, and is not just a matter of
drying out. Intact, setting and hardening stop as soon as the concrete becomes dry.
Rate and Heat of Hydration
 The process by which cement, aggregates and water mix and form a new substance is a
chemical process which has its own unique properties and products. The main product of the
binding of cement and water is heat, which is given off during the hardening of the concrete.
This is known as the heat of hydration.
 When heat of hydration is taken into consideration while designing and pouring concrete, it
can be managed properly during the curing and hardening process. However, if the designers
do not allow for the heat, it can cause issues with cracking and possibly even compromise the
structural integrity of the concrete. It is extremely important to know about heat of hydration
and its effects on concrete from the time it is poured and throughout its lifetime.
 The reaction of compound C3A with water is very fast and is responsible for flash setting of
cement (stiffening without strength development) and thus it will prevent the hydration of C3S
and C2S. However, calcium sulphate (CaSO4) present in the clinker dissolves immediately in
water and forms insoluble calcium sulphoaluminate. It deposits on the surface of C3A forming
a colloidal membrane and consequently retards the hydration of C3A.
 The hydrates of C4AF show a comparatively higher resistance to the attack of sulphates than
the hydrates of calcium aluminate, C3A.
 The hardening of C3S can be said to be catalyzed by C3A and C3S becomes solely
responsible for gain of strength up to 28 days by growth and interlocking of C-S-H gel. The
increase in strength at later age is due to hydration of C2S.
 The rate of heat evolution of the compounds if equal amount of each is
considered will be in the following order: C3A>C3S>C4AF>C2S
 The rate of hydration is increased by an increase in fineness of cement. However, total heat
evolved is the same. The rate of hydration of the principal compounds will be in the following
order: C4AF>C3A>C3S>C2S
Water Requirement for Hydration
About an average 23 per cent (24 per cent C3S, 21 per cent C2S) of water by weight of cement is
required for complete hydration of Portland cement. This water combines chemically with the
cement compounds and is known as bound water. Some quantity of water, about 15 per cent

pg. 15
by weight of cement, is required to fill the cement gel pores and is known as gel water.
Therefore, a total of 38 per cent of water by weight of cement is required to complete the
chemical reaction. The general belief that a water/cement ratio less than 0.38 should not be
used in concrete because for the process of hydration, the gel pores should saturated - is not
valid. This is because as even if excess water is present, complete hydration of cement never
takes place due to deposition of hydration products. As a matter of fact water/cement ratio less
than 0.38 is very common for high strength concretes. If excess water is present, it will lead to
capillary cavities.
Sulphate Attack
 Sulphate attack on concrete is a chemical breakdown mechanism where sulphate ions attack
components of the cement paste.
 The compounds responsible for sulphate attack on concrete are water-soluble sulphate-
containing salts, such as alkali-earth (calcium, magnesium) and alkali (sodium, potassium)
sulphates that are capable of chemically reacting with components of concrete.
 Solid sulphates do not attack the concrete severely but when the chemicals are in
solution, they find entry into porous concrete and react with the hydrated cement
products. Of all the sulphates, magnesium sulphate causes maximum damage to
concrete. A characteristic whitish appearance is the indication of sulphate attack.
 The term sulphate attack denote an increase in the volume of cement paste in concrete
or mortar due to the chemical action between the products of hydration of cement
and solution containing sulphates. In the hardened concrete, calcium aluminate hydrate
(C-A-H) can react with sulphate salt from outside. The product of reaction is calcium
sulphoaluminate, forming within the framework of hydrated cement paste. Because of the
increase in volume of the solid phase which can go up to 227 per cent, a gradual
disintegration of concrete takes place.
Sulphates
[Ma,Ca,etc]
Hydration
Sources of Sulphates
 Most soils contain some sulphate in the form of calcium, sodium, potassium and
magnesium.
 They occur in soil or ground water. Because of solubility of calcium sulphate is low,
ground waters contain more of other sulphates and less of calcium sulphate.
 Ammonium sulphate is frequently present in agricultural soil and water from the use of
fertilizers or from sewage and industrial effluents. Decay of organic matters in marshy
land, shallow lakes often leads to the formation of H2S, which can be transformed into
sulphuric acid by bacterial action.
 Water used in concrete cooling towers can also be a potential source of sulphate
attack on concrete. Therefore sulphate attack is a common occurrence in natural or
industrial situations.

pg. 16
5.6 Test on Cement
Testing of cement can be brought under two categories:
(a) Field testing
(b) Laboratory testing.
Field Testing
It is sufficient to subject the cement to field tests when it is used for minor works. The following are
the field tests:
 Open the bag and take a good look at the cement. There should not be any visible lumps.
The colour of the cement should normally be greenish grey.
 Thrust your hand into the cement bag. It must give you a cool feeling. There should not be
any lump inside.
 Take a pinch of cement and feel-between the fingers. It should give a smooth and not a
gritty feeling.
 Take a handful of cement and throw it on a bucket full of water, the particles should float for
some time before they sink.
 A thin paste of cement should feel sticky between fingers.
The following tests are usually conducted in the laboratory.
(a) Fineness test.
(b Consistency test
(c) Setting time test.
(d ) Soundness test.
(e) Strength test.
(f) Heat of hydration test.
(g) Chemical test.

pg. 17
5.7 Types of Cement
1. Ordinary Portland Cement (OPC)
 The common 3 grades are : - OPC 33, OPC 43, OPC 53
 3 days strength = 50%(1/2) of 28 day strength.
 7 days strength = 67%(2/3) of 28 day strength.
 Fineness = 2250cm2
/gm
 Initial setting time >=30min and Final Setting time <=10hr (600min)
 soundness test not greater than 10mm(Le Chatelier method) and By autoclave test method,
percent, Max 0.8
OPC 33 :
 33 grade cement means that the compressive strength of the cement after 28 days is
33N/mm2
when tested as per Indian Standards under standard conditions. This grade of
cement is used for general construction work under normal environmental condition. It may not
be suitable for concrete grade above M20.
 Rarely used nowadays. As most of them shifted to PPC.
OPC 43 :
 43 grade cement means that the compressive strength of the cement after 28 days is 43
N/mm2
when tested.
 This grade of cement is used for plain concrete work and plastering works. It is suitable to
make concrete mix up to M30.
 43 Grade OPC Cement is commonly used for plastering works, Non-RCC structures, pathways
etc. also used to make precast items, such as tiles, blocks, pipes, etc.
 Unless a project requires very high strength cement, the use of 43 Grade OPC is generally
recommended in general civil construction work such as residential, commercial and industrial
structures. It is used in RCC works, preferably where the grade of concrete is up to M-30.
 The best cement in India for plastering low-rise residential buildings is OPC 43, whereas the
finest cement for plastering high-rise structures is OPC 53.
 Fininishing of all types of building, bridges, culverts, Road, water retaining structures, etc.
OPC 53
 53 grade cement means that the compressive strength of the cement after 28 days is 53
N/mm2
when tested. 53 grade cement has a fast setting time as compared to 43 grade cement.
This grade of cement is not used for ordinary works. It is mostly used for structural purposes as
in reinforced cement concrete.
 Used in Beam, Column, Footin, Slab, Bridge, railway,
 53 Grade OPC provides high strength and durability to structures because of its optimum
particle size distribution and superior crystallized structure.

pg. 18
2. Rapid Hardening Cement (RHC)
 It is also known as high early strength cement. Develops strength rapidly.
 High lime content for this C3S is increased, C2S is decreased + finer grinding.
 Fineness = 3250 cm2
/gm. This factor helps quicker and complete hydration of cement particle
during setting.
 The expansion of cement is limited to 10 mm.
 Rapid hardening cement develops at the age of three days, the same strength as that is
expected to develop in OPC at 7 days.
 Initial setting time = 30min & Final setting time = 10hr(600min)
 1 day compressive strength = 16N/mm2
 3 day compressive strength = 27.5N/mm2
 The extra fineness, however, may be often the cause of development of cracks. Gives much
heat of hydration so not used in mass concrete construction
 RHC is not used in thin RCC member.
 RHC is used so that stength is gained before water is freeze in coldest climate.
 Uses : - Pre-fabricated concrete work, fast removal of formwork, road repair works and cold
weather concrete to prevent from frost action.
3. Extra Rapid Hardening Cement (ERHC)
 It is also known as calcium chloride cement
 RHC + 2% CaCl2
 The normal addition of calcium chloride should not exceed 2 percent by weight of the rapid
hardening cement.
 The strength of extra rapid hardening cement is about 25 per cent higher than that of rapid
hardening cement at one or two days and 10–20 per cent higher at 7 days.
 Uses : - Road repairs, in cold countries, for fast removal of shutter.
 Mixing + Transporting + Placing of concrete should be within 10min.
 Accelerator = Calcium Chloride
4. High Alumina Cement (HAC)
 Bauxite + limestone + iron oxide + increase fineness + high temperature
 It is similar to RHC but C3A is absent.
 Initial setting time = 3.5hr-4hr & Final setting time = 5-6hr
 1 day compressive strength = 30N/mm2
 Uses : - Road repairs, in cold countries, for fast removal of shutter, refractory cement ( hear
resistant), high chemical resistance (no sulphate attack)

pg. 19
5. Sulphate Resisting Cement (SRC)
 It is similar to OPC but C3A is decreased + finer grinding
/gm.
 Initial setting time ≤ 30min & Final setting time ≥10hr(600min)
 Used when climate temperature < 40°C
 Uses : - Lining of sewers, canals, in coastal areas, in sea waters, Marine construction,
foundation and basements, fabrication of pipes
 This cement can be used as an alternative to ordinary Portland cement or Portland pozzolana
 cement or Portland slag cement under normal conditions.
5. Super Sulphated Portland Cement (SSPC)
 80-85% granulated slag + 10-15% CaSO4 + 5% Clinker OPC + Finer grinding
 Water resistance of concretes from supersulphate Portland cements is higher than that of
common Portland cements because of the absence of free calcium oxide hydrate whereas
concretes from Portland cement carry alarge amount of free calcium oxide hydrate which may
wash out and thus weaken them
 It has low heat of hydration and is resistant to chemical attacks and in particular to sulphates.
/gm.
 Initial setting time ≤ 30min & Final setting time ≥10hr(600min)
 Used when climate temperature < 40°C
 Uses : - Lining of sewers, canals, in coastal areas, in sea waters, Marine construction,
foundation and basements, fabrication of pipes
 This cement should not be used in constructions exposed to frequent freezing-and-thawing or
moistening-and-drying conditions
6. Portland Slag Cement (PSC)
 Portland cement clinker + granulated blast furnace slag + gypsum
 The chemical requirements, initial and final setting times, compressive strength of Portland
slag cement are same as that of OPC cement.
/gm
 Initial setting time >=30min and Final Setting time <=10hr (600min)
percent, Max 0.8
 High chemical resistance (sulphate resistance), low heat of hydration, low rate of strength
development than OPC cement.
 Uses : - Marine works, Mass concrete work
7. Low Heat Cement (LHC)
 Low contents of C3A and C3S and more contents of C2S.
/gm
 Initial setting time =1hr and Final Setting time =10hr (600min)
percent, Max 0.8

pg. 20
 Slow rate of hardening, slow strength development, prevent shrinkage and cracking decrease.
 The heat of hydration should not be more than 272 and 314 J/g at the end of 7 and 28 days
respectively.
 The rate of development of strength is slow but the ultimate strength is same as that of OPC.
To meet this requirement, specific surface of cement, fineness is increased to about 3200
cm2
/g.
 Uses : - Mass concreting works, high temperature places, Dam, etc.
8. Portland Pozzolana Cement (PPC)
 Portland cement + pozzolanic materials + finer grinding.
 Pozzolana (siliceous material) + Lime (Ca(OH)2) = Pozzolana-lime compound (cementitious).
 Low rate of strength development, decrease in early stength, low heat of hydration, chemical
resistance, Offer greater resistance to expansion, aggressive water.
/gm
 Initial setting time = 30min and Final Setting time =10hr (600min)
percent, Max 0.8
 The drying shrinkage should not be more than 0.15%
 Uses : - It has low heat evolution and is used in the places of mass concrete such as dams
and in places of high temperature.Mass concreting works, marine works.
9. Quick Setting Cement
 This cement is finer than OPC and Gypsum is not used.
 Gypsum free cement. The quantity of gypsum is reduced and small percentage of aluminium
sulphate(Al2(SO4)3) is added.
 Initial setting time = 5min and Final Setting time = 30min.
 Rapid hardening cement develops higher rate of gain of strength while quick setting cement
sets quickly only and its rate of gain of strength is similar to ordinary Portland cement.
 It is used when concrete is to be laid under water or in running water.
 It is used mostly in under water construction where pumping is involved. Use of quick setting
cement in such conditions reduces the pumping time and makes it economical.
 Quick setting cement may also find its use in some typical grouting operations.
10. Air Entraining Cement
 Vinsol resin or vegetable fats and oils and fatty acids or other air entrainig agent are ground
with OPC.
 Air-entraining admixtures facilitate the development of a system of microscopic air bubbles
within concrete during mixing.
 It is beneficial to use air entrained concrete when placing concrete in areas with freeze-thaw
conditions. Freeze-thaw conditions occur when the temperature of an environment fluctuates
between above freezing temperatures and below freezing temperatures and protects from
cracks and damage of concrete.
12. White Cement and Coloured Cement
 White cement = From pure white limestone (chalk) + clay (free from oxides of iron)
 Sodium alumino fluoride is added during burning in clinker which acts as a catalyst in place of
iron.
 Coloured cement = white cement + 5-10% coloured pigment
 It dries quickly. Has superior aesthetic value, Floor finish, plaster work, ornamental work etc.

pg. 21
13. Water Repellant Cement (Hydrophobic Cement)
 OPC clinker + 0.1% Oleic acid or stearic acid.
 These acids form a thin (monomolecular) film around the cement particles which prevent the
entry of atmospheric moisture.
 The specific surface of hydrophobic cement should not be less than 350 m2
/kg.
 The weak points of hydrophobic cement are its small strength gain during the initial period
because of the hydrophobic films on cement grains which prevent the interaction with water,
but its 28-day strength is equal to that of ordinary Portland cement.
 Uses : - In basements, water tight structure.
STORAGE OF CEMENT
Portland cement is kept in sacks of 0.035 m3
(50 kg) capacity for local use. These are stored for
short period of time in air tight room avoiding moisture and dampness, at some distance from walls
and at some height from floors. The stack should be covered with suitable coverings to avoid
circulation of air through the stack and not more than ten bags should be stacked one over another.

Cement

More Related Content

What's hot

Similar to Cement

More from Umesh Yadav

Recently uploaded

Cement