The document discusses different types of cement. It defines cement and describes its composition and manufacturing process. The main types discussed are ordinary Portland cement (OPC), Portland pozzolana cement (PPC), Portland blast furnace slag cement (PBSF), rapid hardening cement, low heat cement, sulfate resisting cement, and white cement. It provides details on the characteristics and common applications of each cement type.
2. Definition: “Cement is a crystalline compound of calcium silicates and other
calcium compounds having hydraulic properties”.
The product is obtained by pulverizing clinker consisting essentially of hydraulic
calcium aluminates, silicates of varying composition, which hydrates and becomes
hard like stone in contact with water or moist air.
3. • Lime and clay have been used as cementing
material on constructions through many centuries.
• Romans are commonly given the credit for the
development of hydraulic cement, the most
significant incorporation of the Roman’s was the use of
pozzolan-lime cement by mixing volcanic ash from
the Mt. Vesuvius with lime.
• Best know surviving example is the Pantheon in Rome
(128 AD)
• In 1824 Joseph Aspdin from England invented the
Portland cement. The set product of cement , sand
and water has got similar color and strength to that of
a natural stone obtained at Portland of England.
4. The first cement factory in
Bangladesh established in 1940 at
Chattak of Sylhet.
At present there are more than 50
factories in Bangladesh
The total annual production of
cement in Bangladesh is more
than 5 million metric tones.
5. Calcareous Materials
Limestone, cement rock, marine shells
are example of calcareous materials.
Should contain less than 3.3% MgO.
Limestone containing high percentage
of MgO and the percentage is reduced
to less than 5%.
Argillaceous Materials
Rich in silica, supply Silica (SiO2), Alumina
(Al2O3),Iron Oxide (Fe2O3).
Clay, shell, blast furnace slag, ash,
cement rock etc.
6. CaCO3 = CaO+CO2 ( at 700°-1000° Celsius)
2 CaO + SiO2 = 2CaO SiO2 (C2S) (at 1300° -1500° Celsius)
3 CaO + SiO2 = 3CaOSiO2 (C3S) (“)
3 CaO + Al2O3 = 3CaOAl2O3 (C3A) (“)
4 CaO + Al2O3 +Fe2O3 = 4 CaO Al2O3 Fe2O3 (C4AF)
These materials are combined together to form hard, grayish pellets,
which is known as cement clinker.
The lime saturation factor ( CaO/ 2.8 SiO2 +1.2 Al2O3+0.65 Fe2O3)
should be in the range of 0.66 to 1.2. This will ensure the formation of
C2S,C3S and C3A which are responsible for giving strength of
concrete.
Silica modulus (SiO2 / Al2O3 +Fe2O3 ) should be within 2.2 to 3.5
MgO should be below the specific limit which ensures the cement is
sound.
7. These main phases are present in the
clinker and in the non-hydrated
Portland cement.
They are formed at high temperature
(1450°C) in the cement kiln.
Compounds referred as C3S,
C2S,C3A and C4AF are known as the
main crystalline phases of Portland
cement.
8. SI Name of
Compound
Oxide Composition Abbreviation % Function
1 Tri Calcium
Silicate
3CaO.SiO2 C3S 45-55% Responsible for early
and later strength
2 Di Calcium
Silicate
2CaO. SiO2 C2S 20-30% Responsible for later
strength
3 Tri Calcium
Aluminate
3CaO.Al2O3 C3A 6-10% Increases rate of
hydration of C3S. It gives
flash set in absence of
Gypsum
4 Tetra Calcium
Aluminoferrite
4CaO.Al2O3Fe3O3 C4AF 15-20% Hydrates rapidly but
contribution to strength
is uncertain and very
low
9. Other components of cement are
1. Gypsum
2. Free Lime
3. Chlorides
4. Alkalis
5. Magnesium
10. Tri Calcium Silicate & Di Calcium Silicate
1. Tri Calcium Silicate hydrates and hardens rapidly and responsible for early strength
and initial set.
2. Higher percentage of C3S exhibits higher strength.
3. When C3S increases it decreases C2S.
12. 1. Reactivity with Supplementary Cementous compound increases
2. Setting Time Decreases
3. Strength Increases
13. 1. Tri Calcium Aluminate hydrates and hardens the quickest. Liberates a large
amount of heat and contributes somewhat to early strength.
2. Gypsum is added to retard the hydration of C3A.
3. In absence of Gypsum Portland cement sets immediately after adding water.
15. 1. It hydrates rapidly but contributes very little to strength. Its use allows lower kiln
temperature in Portland Cement Manufacturing.
2. The most Portland cement color effects are due to C4AF
3. The higher the C4AF more darker the color of cement.
16. 1. Gypsum (CaSO4·2H2O) is a setting time
retarder, without it cement will set
immediately.
2. To prevent Sulfate expansion in cement
the Sulfate (SO3) content in cement is
limits to 3-3.5%. That’s why Gypsum is
kept less than 5% in cement.
3. The higher the Gypsum content the
longer is setting time of cement.
4. Excess Gypsum leads to the formation of
Calcium Sulfoaluminate,(Ettringite) and it
results in a volume increase in the
concrete, resulting expansion and
cracks.
17.
18. Lime (CaO) which is not combined with other
constituents in clinker is known as free lime.
Free lime is harmful for cement , in presence of
higher free lime causes expansion in cement and
drop early strength.
Free lime normally generated in burning process
Higher free lime causes cement to change of its
color to brown.
Higher lime cement is not a good binder.
19. Higher chloride content leads to
corrosion of steel.
The origin of chloride is mainly from
cement raw material.
20. Higher presence of alkalis leads to
internal expansions and cracking in
concrete due to reaction between
silica and alkali.
The origin of alkali is mainly from
cement raw material and fuels.
21. Air content increases
Bleeding decreases
Heat of hydration increases
Reactivity of SCM increases
Alkali Silica reaction increases
Changes in setting time
Shrinkage decreases
Early Strength up, late strength downs
Water requirement increases
Workability decreases
22.
23. A material which is not soluble in
acid and alkali is known as insoluble
residue.
Insoluble residue is non cementing
material which is present in Portland
cement.
It decreases the early strength of
cement.
The limit of insoluble residue is 0.75
percent of cement.
It comes from limestone, fly ash,
volcanic clay etc.
24. Soluble Fluoride decrease the setting time of cement and reduce the strength and
density.
Soluble Phosphates retard the setting and strength development of plaster.
These materials come from Gypsum
25. Fly Ash
• It is the residue that is left from burning
coal, and this is formed when the
gaseous releases of the coal is efficiently
cooled.
Blast Furnace Slag
• It is a byproduct of the iron and steel
manufacturing process.
• The chemical reaction results in two
products: molten iron metal and molten
blast furnace slag.
26. Advantages
• It is also an environmentally-friendly solution. It improves
the strength over time and thus, it offers greater strength
to the building.
• Increased density and also the long-term strengthening
action of flash that ties up with free lime and thus,
results in lower bleed channels and also decreases the
permeability.
• Aids to keep aggressive composites on the surface
where the damaging action is reduced. It is also highly
resistant to attack by mild acid, water and sulfate.
• It effectively combines with alkalis from cement, which
thereby prevents the destructive expansion.
• It is also helpful in reducing the heat of hydration. The
pozzolanic reaction in between lime and fly ash will
significantly generate less heat and thus, prevents
thermal cracking.
27. Advantages
• It chemically and effectively binds salts and free
lime, which can create efflorescence. The lower
permeability of fly ash concrete can efficiently
reduce the effects of efflorescence.
• Make big savings in concrete material prices
Disadvantages
• The poor quality can increase the permeability
and thus damaging the building.
• Increases setting time.
28. Advantages
Concrete containing BFC is less permeable,
It has lower hydration,
Higher ultimate compressive strengths,
It is resistant to sulfate-acid attack and aggressive
chemicals, resistant to many forms of deleterious
attack.
It has better workability and finish ability than normal
concrete.
Disadvantages
Sets slower than normal cement.
29. Fineness
Soundness
Setting Time
Strength
Specific Gravity
Heat of Hydration
Loss of Ignition
Color
30. Fineness
1. The fineness of cement effects the hydration rate of
cement and thus the rate of strength gain.
2. Greater fineness increases surface area so that
increases hydration rate, heat of hydration and
greater early strength.
3. The effect on strength can be seen in 7 days.
4. The coarser cement will result in higher ultimate
strength and lower early strength.
5. Coarse cement results in creating porosity in
concrete thus reduces durability.
6. Fineness can be measured by – Sieve analysis, turbid
meter, Blain Air Permeability apparatus
31. Effect of Fineness
1. Increases water requirement
2. Increases Strength
3. Shrinkages Increases
4. Setting time decreases
5. Heat of hydration increases
6. Bleeding decreases
7. Air Content decreases
8. Workability Decreases
32. Soundness
The destructive expansion caused by excessive
amount of free lime and magnesia.
ASTM C 150 specifies for Portland Cement a
maximum autoclave expansion (for presence of
MgO) of 0.80 percent.
There is no specification limit for free lime but
Lechatelier expansion is restricted to 10 mm .
33. Setting Time
Initial Set – Occurs when the paste begins to stiff
considerably. Should be greater than 45 minutes.
Final Set – Occurs when cement is hardened enough
to sustain some load. Should be less than 420 minutes.
Setting Time affects by
1. Fineness ( Setting time Decreases with increasing of
fineness)
2. Water Cement Ratio ( Setting time increases when
water cement ration increases)
3. Gypsum content increases setting time
4. Admixtures
34. Strength
ASTM Standard for Compressive Strength of Cement
1. For 3 Days:1890 psi
2. For 7 Days: 2900 psi
3. For 28 Days: 3620 psi
35. Strength
It depends on various factors
1. Water-Cement ratio
2. Cement-Fine aggregate ratio
3. Type and grading of aggregate
4. Manner of mixing
5. Curing conditions
6. Moisture Content
7. Fineness of Cement
36. Specific Gravity
1. It is used in mixture proportion calculating.
2. The specific gravity of cement is normally 3.15
37. Heat of Hydration
1. Increases when water cement ratio,
fineness and curing temperature
increases.
2. Higher heat of hydration causes
considerable loss of strength and
regression at later ages.
38. Loss of Ignition (LOI)
1. The weight loss of a sample at 900° -1000°
Celsius.
2. At high LOI indicates pre hydration and
carbonation, which may be caused by
prolonged storage or adulteration during
transportation.
3. Higher LOI causes loss of strength.
39. Factors affecting choice of cement:
Following factors govern choice of cement.
Durability Characteristics
Functional requirement - Deflection, crack width
etc.
Design parameters- Strength, fineness, setting
time requirement etc.
Speed of construction- Time for construction
etc.
Environnemental Conditions- Ground conditions,
Soluble Salt, Sulfate, Chemical plants etc.
43. 33 grade OPC Cement
It is used for normal grade of concrete up to M-20,
plastering, flooring, grouting of cable ducts etc. The
fineness should be between 225 and 280 m2/kg.
43 grade OPC Cement
It is the most widely used general purpose cement.
For concrete grades up to M-30, precast elements.
For marine structures but C3A should be between 5 -
8%.
44. 53 grade OPC Cement
For concrete grade higher than M-30, PSC works, bridge, roads, multistoried buildings
etc.
For use in cold weather concreting.
For marine structures but C3A should be between 5 - 8%.
45. Portland Pozzolana Cement: (using fly ash):
It gives low heat of hydration and reduces the
leaching of calcium hydroxide. This cement should
be used only after proper evaluation.
It is used for :
Hydraulic structures- dams, retaining walls
Marine structures
Mass concrete works- like bridge footings
Under aggressive conditions
Masonry mortar and plastering.
46. Portland Slag Cement (PSC)
OPC + granulated slag: It gives low heat of hydration. The
slag should be more than 50% and up to 70%.
It is used for
For concrete grade higher than M-30, PSC works, bridge,
roads, multistoried buildings etc.
For use in cold weather concreting.
For marine structures but C3A should be between 5 - 8%.
47. SRC- Sulfate Resisting Cement: (C3A < 5%)
Sulfate Resisting Portland Cement is a type of
Portland Cement in which the amount of tri calcium
aluminate (C3A) is restricted to lower than 5% and
2C3A + C4AF lower than 25%.
The percentage of C4AF is comparatively higher in
this cement.
The SRC can be used for structural concrete
wherever OPC or PPC or Slag Cement are usable
under normal conditions.
48. SRC- Sulfate Resisting Cement: (C3A < 5%)
The use of SRC is recommended for following applications:
Foundations, piles
Basement and underground structures
Sewage and water treatment plants
Chemical factories
Suitable for underground works where Sulfate is present in the
Soil and water.
Attention:
Sulfate resisting cement is not suitable where there is danger of
chloride attack. This will cause corrosion of rebar.
If both Chlorides and Sulfates are present, Ordinary Portland
Cement with C3A between 5& 8 should be used.
49.
50.
51. Low Heat Cement
Heat liberated during setting is low, due to presence
of C4AF and C2S.
Contains low percentage of C3S and C3A.
Shrinkage and cracks are reduced.
This type of cement is used for mass scale concrete
work where low liberation of heat is desired such as
dams, roofs etc.
52. Rapid Hardening Cement
Lime saturation factor is relatively higher and the final
product is ground to more fineness.
Contains high percentage of C3S and C3A.
More expensive.
This type of cement is used for emergency
construction where high early strength is desired.
53. White Cement
Raw materials are free from iron impurities.
More expensive.
This type of cement is used for fare face concrete ,
cement paints, colored cements etc.
54. Portland Cement is a moisture sensitive material
If kept dry it will remain its quality.
When stored in moist and damp condition it will set
more slowly and has less strength.
When storing bagged cement, a shaded area or
ware house is preferred.
When storing cement bags at outdoor it should be
stacked on pallets and covered with waterproof
covering.
Storage of bulk cement should be in bin or silo.