Topic 1 Cement Prof Mayur M Maske Ho

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

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 1500 oc. Mayur M Maske 2

Dry process Cement Manufacturing Wet process Mayur M Maske 3

Wet Process Mayur M Maske 4

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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. Mayur M Maske 6

• 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. Mayur M Maske 7

• 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. Mayur M Maske 8

• 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. Mayur M Maske 9

• The lower part (clinkering zone) have temperature in between 1500 -17000 C. • At this temperature lime and clay are reacts to yielding calcium aluminates and calcium silicates. Mayur M Maske 10

• 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 510 mm. Mayur M Maske 11

• 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. Mayur M Maske 12

Dry Process Mayur M Maske 13

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• 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. Mayur M Maske 15

• 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. Mayur M Maske 16

• Raw materials are mixed in required proportions so that average composition of the final product is maintained properly. Mayur M Maske 17

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 Quality Inferior quality Superior quality Cost of production High Low Overall cost Cheaper Costly Physical state Raw mix (solid) Mayur M Maske Slurry (liquid) Higher 18

Cement Manufacturing • Cement Production at KHD designed Novotroitsk Cement Plant. https: //www. youtube. com/watch? v=0 EH 9 AAAo. O 2 M • http: //nptel. ac. in/courses/103106108/Lecture%2024. pdf Mayur M Maske 19

Chemical Constituents Lime (Ca. O) Excess reduces strength and make cement 60 -66% disintegrate and in less amount reduces strength and makes it quick setting. Silica (Si. O 2) 17 -25% Provides strength to cement Alumina (Al 2 O 3) 3 -8% Calcium Sulphate (Gypsum) Helps in quick setting Enhances initial setting of cement Iron Oxide 2 -6% Gives color, Strength and hardness. Sulphur trioxide (SO 3) 1 -3% Provides soundness Alkali Oxides (Na 2 O and K 2 O) Magnesium Oxide (Mg. O) 0. 5 -1. 5% in excess makes cement efflorescent 1 -5% Mayur M Maske 20

Bogue’s Compounds Mayur M Maske 21

Bogue’s Compounds Tricalcium silicate (C 3 S) • 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 = C 3 S reduced. ) Mayur M Maske 22

Bogue’s Compounds Dicalcium silicate (C 2 S) • Second most abundant 20 to 50% • Develops strength more slowly than C 3 S(After four weeks) • Produces less heat upon hydration than C 3 S, 12 cal/gm. Mayur M Maske 23

Bogue’s Compounds Tricalcium aluminate (C 3 A) • First to react. • Very early age strength (one to three days) • May reduce advanced age strength. • High early-strength cement = higher concentrations of C 3 A, (10% and 15%. ) • High heat of hydration, 212 cal/gm Mayur M Maske 24

Bogue’s Compounds Tetracalcium aluminoferrite (C 4 AF) • Bi product 9 -10% • Hydrates rapidly, 69 cal/gm • Contributes very less to actual strength. • Influences color. Mayur M Maske 25

Hydration Mayur M Maske 26

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. Mayur M Maske 27

HYDRATION Hydration Cement + Water = C-S-H + Ca. OH+ Heat Mayur M Maske 28

HYDRATION When water is added, the reactions which occur are mostly exothermic, that is, the reactions generate heat. Mayur M Maske 29

HYDRATION Ref. http: //www. cptechcenter. org/technical-library/documents/imcp_hydration_poster. pdf Mayur M Maske 30

HYDRATION Mayur M Maske 31

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. Mayur M Maske 32

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. Mayur M Maske 33

HYDRATION False setting It is abnormal premature stiffening of cement within a few minutes of mixing with water. Flash setting C 3 A 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 Mayur M Maske 34

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. Mayur M Maske 35

Physical Properties of OPC 1. Fineness, 2. Setting time, 3. Compressive strength, 4. Soundness. Mayur M Maske 36

Fineness of Cement Fineness defines the surface area of cement particles present per unit weight. Higher fineness means more particles in unit weight Mayur M Maske 37

Fineness of Cement Blaine's air permeability test Mayur M Maske 38

Fineness of Cement • Increase in fineness increases workability. • Increase in fineness increases rate of hydration. • Compressive strength of concrete increases with fineness. Ref: - 27 th Conference on OUR WORLD IN CONCRETE & STRUCTURES: 29 30 August 2002, Singapore Article Online Id: 100027011 Mayur M Maske 39

Standard consistency of Cement Mayur M Maske 40

Setting time of Cement Mayur M Maske 41

Compressive Strength of Cement Mayur M Maske 42

The Soundness of Cement 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. Mayur M Maske 43

The Soundness of Cement 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. Mayur M Maske 44

Types of Cements Mayur M Maske 45

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 Mayur M Maske 46

Sr No Types Of Cement Reference Indian Standard 8 9 10 Quick Setting Cement Super Sulphated Cement Low Heat Cement — IS: 6909 IS: 12600 11 Portland Pozzolana Cement (Fly ash based) IS: 1489 P-1 12 Portland Pozzolana Cement (Calcined based) IS: 1489 P-2 13 14 15 16 Air Entraining Cement Coloured Cement: White Cement Hydrophobic Cement Masonry Cement — IS: 8042 IS: 8043 IS: 3466 Mayur M Maske 47

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: - http: //civilblog. org/2014/08/22/20 -different-types-cements-available-in-india-and-their-respective-indian-standards/# Mayur M Maske 48

Thank you Mayur M Maske 49