1. CEMENT

2. History
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 by the Vesuvius with lime.
Best know surviving example is the Pantheon in Rome
In 1824 Joseph Aspdin from England invented the Portland cement

3. Introduction · Popular as building material.
·  Material with adhesive & cohesive properties.
·  To bind the sand & coarse aggregate together
·  To fill voids in between sand & coarse aggregate particle to form a compact mass.

4. Categories of Cement
Hydraulic Cement: Would set & hardened under water. E.g. Portland cement
Non Hydraulic Cement: Would not set & hardened in water. E.g. POP- plaster of paris

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. Portland cement
Defined as a product obtained by finely pulverizing clinker produced by fusion of aluminosilicates and calcareous materials.

7. Clinker
In the manufacture of Portland cement, clinker is lumps or nodules, usually 3-25 mm in diameter, produced by sintering/fusing limestone and alumino-silicate during the cement kiln stage.

8. Portland cement
Cement is made by heating limestone (calcium carbonate) with small quantities of other materials (such as clay) to 1450 °C in a kiln, in a process known as calcination, whereby a molecule of carbon dioxide is liberated from the calcium carbonate to form calcium oxide, or quicklime, which is then blended with the other materials that have been included in the mix.
The resulting hard substance, called 'clinker', is then ground with a small amount of gypsum into a powder to make 'Ordinary Portland Cement', the most commonly used type of cement

9. Portland cement is a basic ingredient of concrete, mortar and most non- speciality grout. The most common use for Portland cement is in the production of concrete. Concrete is a composite material consisting of aggregate (gravel and sand), cement, and water. As a construction material, concrete can be cast in almost any shape desired, and once hardened, can become a structural (load bearing) element. Portland cement may be grey or white.

10. Portland cement 33 grade, 43 grade, 53 grade Sr. no
Physical requirement
Method of testing
33 Grade
43 Grade
53 Grade 1
Fineness
Blaine’s air permissibility
225 2
Soundness
Le Chatelier apparatus
10mm
Autoclave
0.8% 3
Setting time
Vicat apparatus
Initial (min) 30
Final (max)
600 4
Compressive strength
72hr 16 23 27
168hr 22 33 37
672hr 43 53

11. Chemical composition (RAW MATERIALS)
The fundamental chemical compounds to produce cement clinker are:
Lime (CaO)
Silica (SiO2)
Alumina (Al2O3)
Iron Oxide (Fe2O3)
Magnesia
Sulphur Trioxide
Alkalis
Raw materials used in the production of clinker cement

12. Typical constituents of Portland cement
Function
Mass %
Calcium oxide, CaO
Controls strength & soundness. Its deficiency reduces strength & setting time
60-65%
Silicon oxide, SiO2
Gives strength. Excess of it causes slow setting
17-25%
Aluminum oxide, Al2O3
Responsible for quick setting. if in excess , lowers strength
 3-8%
Ferric oxide, Fe2O3
Gives color & help in fusion of different ingredients.
 0.5-6%
MgO
Imparts color & hardness. If in excess causes cracks in mortar & concrete & unsoundness
0.5-4%
Na2O+K2O
These are residues & if in excess causes effloroscence & cracking %
TiO2, P2O5 %
SO3
Makes cement sound
1-2

13. Typical constituents of Cement clinker
Compounds formed in the burning process which have properties of setting & hardening in the presence of water known as Bogue compounds.

14. Typical constituents of Portland clinker plus Gypsum
Formula
CCN
Name
Mass %
Tricalcium silicate
3CaO · SiO2
C3S
Alite
45-75%
Dicalcium silicate
2CaO · SiO2
C2S
Belite
 7-32%
Tricalcium aluminate
3CaO · Al2O3
C3A
Celite
 0-13%
Tetracalcium aluminoferrite
4CaO · Al2O3 · Fe2O3
C4AF
Felite
 0-18%
Gypsum
CaSO4 · 2 H2O
CSH2
 2-10%

15. CEMENT The 4 main chemical compound are: Dicalcium Silicate (C2S)
Slow strength gain – responsible for long term strength(after year or more)
25-40% (Approximately percentage in OPC)
260 (J/g) – Heat of hydration
Tricalcium Silicate (C3S)
Rapid strength gain – responsible for early strength ( eg: 7 days)
25-50% (Approximately percentage in OPC)
500 J/g (Heat of hydration)
Tricalcium Aluminate (C3A)
Quick setting (controlled by gypsum): susceptible to sulphate attack
5-11% (Approximately percentage in OPC)
865 J/g (Heat of hydration)
Tetracalcium Aluminoferrite (C4AF)
Little contribution to setting or strength; responsible for grey colour of OPC
8-14% (Approximately percentage in OPC)
420J/g (Heat of hydration)

16. Tricalcium silicate (C3S). Best cementing material
Tricalcium silicate (C3S).  Best cementing material. Makes clinker easier to grind. Increases resistance to freezing and thawing.
Hydrates and hardens rapidly and is largely responsible for initial set and early strength (7days). Portland cements with higher percentages of C3S will exhibit higher early strength.
Higher content will increase heat of hydration and solubility of cement.

17. Dicalcium silicate (C2S)
Dicalcium silicate (C2S).  Hydrates and hardens slowly and is largely responsible for strength increase (after a year or more).
Imparts resistance to chemical attack
Increase in content will make clinker harder to grind, reduces early strength, reduces resistance to freezing and thawing at early stages and decreases heat of hydration.

18. Tricalcium aluminate (C3A).  Hydrates and hardens the quickest. 
Liberates a large amount of heat almost immediately and contributes somewhat to early strength. 
Gypsum (2-3%) is added to portland cement to retard C3A hydration.  Without gypsum, C3A hydration would cause portland cement to set almost immediately after adding water.
Has high heat of hydration results in cracking of cement due to volume changes.
Higher content reduces setting time, weakens to sulphate attack and lowers ultimate strength.

19. Tetracalcium aluminoferrite (C4AF)
Tetracalcium aluminoferrite (C4AF).  Hydrates rapidly but contributes very little to strength. 
  Most portland cement color effects are due to C4AF.
Poorest cementing value.
Higher content reduces the strength slightly.

20. Flow chart of cement manufacturing

22. Manufacturing of cement
Raw materials
Calcareous and argillaceous materials
Types-
Dry process
Wet process

23. Dry process
Limestone and clay are grounded to fine powder separately and are mixed.
Water is added to make thick paste. Cakes of this paste(14% of moisture) are charged into rotary kiln.
Product obtained after calcination in rotary kiln is called clinker.

24. Aeration of clinker leads to absorption of moisture and carbon dioxide.
So clinker is cooled rapidly to preserve the metastable compund and their solid solutions
Then grounded in tube mills and mixed with gypsum(2-3%).
stored in bags of 50 kgs.

26. Wet process Steps : Mixing Burning Grinding
The crushed raw materials are fed into ball mill with little amount of water.
Steel balls in mill pulverizes the raw materials which forms slurry with water.

27. Slurry is then passed into silos(storage tanks) where proportioning of compounds are adjusted according to desired chemical composition.
The corrected slurry is fed into rotary kiln where it looses its moisture and forms lumps or nodules.
Then these lumps are burned at temperature of degree.

28. Nodules are changed into clinker at this temperature.
Then grinding is carried out and gypsum is added and sent to silos.

29. Comparison Low cost excavating and grinding raw materials
Accurate control of composition
Homogeneity of slurry
Economic utilization of fuel
Disadvantages- longer kilns costs more
Less responsive to a variable clinker demand than short kilns( dry process)

31. Field Test
Colour
Physical properties
Presence of lumps
Strength

32. 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.

33. 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.

34. 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.

35. Fineness Test: degree of fineness
3 methods
The sieve method (grain size)
The air permeability method (surface area)
Sedimentation method (surface area)
Conditions affecting fineness:-
Chemical composition
Degree of calcination
Time of grinding
The character of pulverizing machinery

36. v It is expressed in terms of specific surface of cement.
b)   Fineness
v     Fineness of cement is a measure of the sizes particles of cement.
v     It is expressed in terms of specific surface of cement.
v     Most important factor that will determines the properties of cement
v     Process of Hydration
 Since hydration starts at the surface of the cement particles it is the total surface area of cement that represents the material available for hydration
The finer the cement is ground, the greater will be its specific surface.
So the rate of hydration depends on the fineness of cement particles & for rapid development of strength higher fineness necessary.
Fineness cement leads to a stronger reaction with alkali reaction aggregate & makes a paste though not necessarily concrete, exhibiting a higher shrinkage & a creates proneness to cracking.

37. However, fine cement bleed less than a coarse one.
Finer grinding increases the speed with which the various constituents reacts with the water
Fineness of grinding is of some importance in relation on the workability of concrete mixes.
Greater fineness increases the cohesiveness of a concrete mix
Finer grinding reduces the chances of bleeding of concrete

38. Finer the cement, more is the strength since surface area for hydration will be large.
Sieve method:-
Sieve test is conducted with the standard BIS sieve no. 9.
100g is taken and sieved for 15 min
Residue left should not exceed the values

39. Type of cement
Percentage of residue by weight
Ordinary Portland cement 10
Rapid hardening concrete 5
Portland Puzzolana cement

40. Consistency
It is used to determine the % of water required for preparing cement pastes for other tests
Procedure:
Take 300g cement, add 25-30% or 90g of water
Mix water and cement on a non-porous surface.

41. 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.

44. Setting Time
Cement paste setting time is affected by a number of items including: cement fineness, water-cement ratio, chemical content (especially gypsum content) and admixtures. 
Setting tests are used to characterize how a particular cement paste sets.  For construction purposes, the initial set must not be too soon and the final set must not be too late. 
Normally, two setting times are defined:
Initial set.  Occurs when the paste begins to stiffen considerably.
Final set.  Occurs when the cement has hardened to the point at which it can sustain some load.

45.  d) Setting time
The time from the addition of water to the initial & final setting stage.
Also refers to time of changes of the cement paste from a liquid to a rigid stage.
The setting process is accompanied by the temperature changes, hydration resolves in the formation of the gel around each parties of cement.
The means of controlling the rate at which cement stiffened by intergrading a measured quantities of gypsum
Initial Setting
·  Defined as the beginning of the noticeable stiffening in the cement paste.
It’s corresponds to a rapid rise in temperature.
·  Normally takes about 45 – 175 minutes.
-          

46.  Final Setting Time
·  Refers to completion of setting, which corresponds to the peak temperature in the cement paste.
·  The stiffening of cement paste increases as the volume of the gel increases and the stage at which this is complete, the final hardening process begins.
·  Normally takes between 3 hours to 10 hours for this to happen.
Hardening
Referred to the gained of the strength of the cement paste.
During the setting time the cement gained very little strength

47. Procedure
A neat paste is prepared with 0.85 times the water required to give paste a normal consistency.
Start stop watch as soon as water is added to cement.
Fill the mould with cement paste and level the surface.
Place the mould in Vicat’s apparatus and lower the needle just at surface.

48. Release the needle quickly and it will penetrate the test block.
Repeat the procedure until reading on graduated scale is 5 mm from the bottom of the mould.
Note the time on stop watch.
Final setting time is considered when on releasing the needle makes an impression but does not penetrate.

49. Soundness
When referring to portland cement, "soundness" refers to the ability of a hardened cement paste to retain its volume after setting without delayed destructive expansion.  This destructive expansion is caused by excessive amounts of free lime (CaO) or magnesia (MgO). 

50. Procedure
Place mould on glass sheet and fill with cement paste by mixing 100g of cement with 0.78 times.
The mould is covered with a glass sheet and a small weight is placed on the covering glass sheet.
Submerge the mould and take out after 24 hrs. and measure distance separating indicating points.

51. The mould is then again submerged in water and now boiled for 3 hrs and remove mould cool it down and measure again distance between indicator points.
The difference between two measurements gives unsoundness of cement.

53. Specific Gravity Test
Specific gravity is normally used in mixture proportioning calculations.  The specific gravity of portland cement is generally around 3.15 while the specific gravity of portland-blast-furnace-slag and portland-pozzolana cements may have specific gravities near 2.90.  
The standard specific gravity test is obtained using Le Chatelier’s Flask :
64 gm, 0.73 S.G

55. Flask is filled with kerosene / naphtha
Flask is immersed in a const temp water bath & reading recorded
Weighed quantity is then introduced
Stopper is placed.
Flask is rolled in inclined position
Flask is again immersed & final reading is recorded.
Difference represents vol of liquid displaced
Specific gr=Wt of cement/ displaced vol of liquid in ml.

56. Types of Cement

57. Hydration of cement
When cement comes in contact with water, the hydration start depositing on the outer periphery of nucleus of hydrated cement.
This reaction proceeds for 2-5 hrs and called dormant period.
As hydration proceeds the rate starts decreasing due to presence of hydrated molecule deposited on cement nucleus.

58. Among the types of Portland Cement are: a) Ordinary Portland Cement
b) Rapid Hardening Portland Cement c) Low Heat Portland Cement d) Sulphate Resisting Portland Cement e) Portland Blast Furnace Cement f) White Cement g) High Alumina Cement
h) water repellent cement i) Air Entraining Portland Cement
j)Supersulphate portland cement

59. Portland puzzolana cement
Quick setting Portland cement
Masonry cement
Calcium chloride cement
Water proof cement

60. ORDINARY PORTLAND CEMENT
Has a medium rate of hardening
Suitable for most type of work
Commonly used for structural purposes

61. RAPID HARDENING PORTLAND CEMENT
High lime content
By increasing C3S content
Hardens more rapidly than OPC
Similar composition of OPC but different proposition
More finely grounded to increase rate of hydration that will increase rate of early hardening
Useful when concreting in cold weather
It produces a strength approximately 50% higher than OPC at 3 days though long term strength are similar.

62. Properties
Initial setting time
30 mins (min)
Final setting time
10 hrs (max)
Compressive strength
1 day
16 N/mm2
3 day
27.5 N/mm2
USES:-
Repair of roads, bridges, when load is applied in a short duration of time

63. Supersulphate portland cement
By blending granulated blast furnace slag 70%, calcium sulphate & small quantity of 33grade OPC
C3A is susceptible to sulphates hence limited to <3.5 %
Or by addition of extra iron oxide

64. Properties
Initial setting time
30 mins (min)
Final setting time
600 mins (max)
Compressive strength
3 day
15 N/mm2
7 day
22 N/mm2
Low heat of hydration
Resistant to chemical attacks
In particular sulphates
USES:-
It is used in places with temp below 40°C, hydrallic engineering installations,moist places,rcc

65. LOW HEAT PORTLAND CEMENT
Contains small percentage of Tri-calcium aluminate that have the highest heat evolution and high dicalcium silicates and tetracalcium aluminoferrite.
Rate of gain of strength is slower than OPC but it's ultimate strength is same as OPC
Hardens and evolves heat slower than OPC
Suitable for mass construction such as concrete dam and massive foundation where heat must be avoided in order to prevent cracking.

66. WHITE CEMENT Made using china clay, that contains very little iron.
One of the most expensive Portland Cements
Used for the production of white or coloured concrete by adding pigments.
It’s primary use is for architectural concrete products, cement paints, tile grouts and decorative concrete

67. Water repellent cement
acids form small layer around cement particles which prevent moisture
Small amount of hydrophobic surfactants such as stearic acid, boric acid or oleic acid is mixed with pcc.
Gives water resistance and water impermeability
Suitable for basements and for making water tight concrete.

68. Water proof cement
manufactured by adding strearates of Ca and Al and gypsum treated with tannic acid at time of grinding.
Resistant to penetration of water 
Water retaining structures.

69. PCC By grinding portland cement and puzzolana (10-25%).
Lower rate of strength development
Has low heat of evolution and is used in places of mass concrete and in high temp. places

70. Quick setting Portland cement
Gypsum is reduced and small percentage of aluminium sulphate is added.
Grounded into finer than OPC
Initial setting time – 5min.
Final setting time- 30 min.
Used when concrete is laid under water or in running water.