1. Prof. Mayur M. Maske HoD Civil Engineering(Diploma) RIT, Rajaramnagar
Topic 1: Cement
Prof. Mayur M. Maske
HoD
Civil Engineering(Diploma)
RIT, Rajaramnagar
Mayur M Maske

2. Cement
Cement is a powdered material which when mixed with water forms a paste that hardens slowly.
It is a powdered mixture of argillaceous & calcareous material burnt at 1500oc.
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3. Cement Manufacturing
Dry process
Wet process
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4. Wet Process
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6. Wet Process Raw materials are crushed, powdered and stored in silos.
The clay is washed with water in wash mills to remove adhering organic matter and it is stored separately.
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7. Powdered lime stone and wet clay are allowed to flow in channel and transfer to grinding mills where they are intimately mixed and paste is formed known as slurry.
Slurry is led to correcting basin where chemical composition may be adjusted.
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8. Then it is called as raw mix or corrected slurry.
The slurry contains 38-40% water stored in storage tank and kept ready for feeding to a rotary kiln.
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9. Burning fuel, like powdered coal or oil or hot gases.
Burning is carried out in rotary kiln which rotating at 1-2 rpm at its longitudinal axis.
Burning fuel, like powdered coal or oil or hot gases.
These are forced through the lower end of the kiln so long hot flame is produced.
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10. The lower part (clinkering zone) have temperature in between 1500-17000C.
At this temperature lime and clay are reacts to yielding calcium aluminates and calcium silicates.
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11. The size of the clinker is varies from 5-10mm.
This aluminates and silicates of calcium fuse to gather to form small and hard stones are known as clinker.
The size of the clinker is varies from 5-10mm.
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12. Cooled clinkers are ground to fine powder in ball mill.
2-3% powdered gypsum is added as retarding agent during final grinding.
Hence resulting cement does not settle quickly, when comes in contact with water.
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13. Dry Process
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15. Lime stone or chalk and clay are crushed into gyratory crusher to get 2-5 cm size pieces.
Crushed material is ground to get fine particle into ball mill or tube mill.
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16. Each material after screening stored in a separate hopper.
The powder is mixed in require proportions to get dry raw mix which is stored in silos (storage tank) and kept ready to be fed into the rotary kiln.
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17. Raw materials are mixed in required proportions so that average composition of the final product is maintained properly.
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18. Comparison of processes
Criteria
Dry
Wet
Hardness of raw material
Quite hard
Any type of raw material
Fuel consumption
Low
High
Time of process
Lesser
Higher
Quality
Inferior quality
Superior quality
Cost of production
Overall cost
Cheaper
Costly
Physical state
Raw mix (solid)
Slurry (liquid)
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19. Cement Manufacturing
Cement Production at KHD designed Novotroitsk Cement Plant.
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20. Chemical Constituents
Lime (CaO)
60-66%
Excess reduces strength and make cement disintegrate and in less amount reduces strength and makes it quick setting.
Silica (SiO2)
17-25%
Provides strength to cement
Alumina (Al2O3)
3-8%
Helps in quick setting
Calcium Sulphate (Gypsum)
Enhances initial setting of cement
Iron Oxide
2-6%
Gives color, Strength and hardness.
Sulphur trioxide (SO3)
1-3%
Provides soundness
Alkali Oxides (Na2O and K2O) %
in excess makes cement efflorescent
Magnesium Oxide (MgO)
1-5%
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21. Bogue’s Compounds
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22. Bogue’s Compounds Tricalcium silicate (C3S)
Most abundant (more than 50% of the total compounds present)
Hydrates and hardens quickly.
Influences setting time and early age strength
Early strength development (First four weeks).
Generation of heat 58 cal/gm. (control of heat of hydration = C3S reduced.)
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23. Bogue’s Compounds Dicalcium silicate (C2S)
Second most abundant 20 to 50%
Develops strength more slowly than C3S(After four weeks)
Produces less heat upon hydration than C3S, 12 cal/gm.
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24. Bogue’s Compounds Tricalcium aluminate (C3A) First to react.
Very early age strength (one to three days)
May reduce advanced age strength.
High early-strength cement = higher concentrations of C3A, (10% and 15%.)
High heat of hydration, 212 cal/gm
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25. Bogue’s Compounds Tetracalcium aluminoferrite (C4AF) Bi product 9-10%
Hydrates rapidly, 69 cal/gm
Contributes very less to actual strength.
Influences color.
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26. Hydration
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27. HYDRATION
Hydration is a chemical reaction in which the major compounds in cement form chemical bonds with water molecules and become hydrates or hydration products.
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28. HYDRATION
Hydration
Cement + Water = C-S-H + CaOH+ Heat
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29. HYDRATION
When water is added, the reactions which occur are mostly exothermic, that is, the reactions generate heat.
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30. HYDRATION
Ref.
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31. HYDRATION
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32. HYDRATION
Factors affecting the setting 1- Water/cement (w/c) ratio – The setting time of cement increases with the increase of w/c ratio. 2- Temperature and relative humidity - The setting time of cement decreases with a rise in temperature and decrease of relative humidity.
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33. HYDRATION
Factors affecting the setting 3-Fineness of cement - The setting time of cement decreases with a rise in fineness of cement. 4- Chemical composition of cement.
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34. HYDRATION
False setting It is abnormal premature stiffening of cement within a few minutes of mixing with water. Flash setting C3A reacts violently with water causing liberation high amount of heat causing rapid setting of cement, and leading to form porous microstructure that the product of hydration
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35. HYDRATION
False setting differs from flash set in : - No appreciable heat is evolved. - Remixing the cement paste without addition of water restores plasticity of the paste until it sets in the normal manner and without a loss of strength.
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36. Physical Properties of OPC
Fineness,
Setting time,
Compressive strength,
Soundness.
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37. Fineness of Cement
Fineness defines the surface area of cement particles present per unit weight. Higher fineness means more particles in unit weight
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38. Fineness of Cement
Blaine's air permeability test
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39. Fineness of Cement Increase in fineness increases workability.
Increase in fineness increases rate of hydration.
Compressive strength of concrete increases with fineness.
Ref:- 27th Conference on OUR WORLD IN CONCRETE & STRUCTURES: August 2002, Singapore Article Online Id:
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40. Standard consistency of Cement
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41. Setting time of Cement
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42. Compressive Strength of Cement
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43. Soundness of Cement
The property by virtue of which the cement does not undergo any appreciable expansion (or change in volume) after it has set, thus eliminating any chances of disrupting the mortar or concrete.
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44. Soundness of Cement
The property by virtue of which the cement does not undergo any appreciable expansion (or change in volume) after it has set, thus eliminating any chances of disrupting the mortar or concrete.
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45. Types of Cements
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46. Reference Indian Standard
Sr No
Types Of Cement
Reference Indian Standard 1
Ordinary Portland Cement 33 Grade
IS:269 2
Ordinary Portland Cement 43 Grade
IS:8112 3
Ordinary Portland Cement 53 Grade
IS:12269 4
Rapid Hardening Cement
IS:8041 5
Extra Rapid Hardening Cement — 6
Sulphate Resisting Cement
IS:12330 7
Portland Slag Cement
IS:455
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47. Reference Indian Standard
Sr No
Types Of Cement
Reference Indian Standard 8
Quick Setting Cement — 9
Super Sulphated Cement
IS:6909 10
Low Heat Cement
IS:12600 11
Portland Pozzolana Cement (Fly ash based)
IS:1489 P-1 12
Portland Pozzolana Cement (Calcined based)
IS:1489 P-2 13
Air Entraining Cement 14
Coloured Cement: White Cement
IS:8042 15
Hydrophobic Cement
IS:8043 16
Masonry Cement
IS:3466
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48. Reference Indian Standard
Sr No
Types Of Cement
Reference Indian Standard 17
Expansive Cement — 18
Oil Well Cement
IS:8229 19
Rediset Cement 20
Concrete Sleeper Grade Cement
IRS-R 40 21
High Alumina Cement
IS:6452 22
Very High Strength Cement
Reference:-
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49. Thank you
Mayur M Maske