Concrete Technology: Cement Production and Aggregates Unit 1 Part 1

Que1.1. What’s cement? Also give its composition. 

Answer  Cement  1. Cement is a hydraulic binder and is defined as a finely base inorganic  material which, when mixed with water, forms a paste which sets and  hardens by means of hydration  responses and processes which, after  hardening retains its strength and stability indeed under water.  2. Cement is the admixture of calcareous, siliceous, argillaceous and other  substances.  Chemical Composition Cement has the following approximate  chemical composition  1. The major  ingredients are  Lime( CaO) 60- 63  ii. Silica( SiO2) 17- 25  iii. Alumina( Al2O3) 03- 08  2. The  supplementary  ingredients are  Iron oxide( Fe2O3)0.5- 06  ii. Magnesia( MgO)1.5- 03  iii. Sulphur tri oxide( SO3) 01- 02  iv. Gypsum 01 to 04  

Que1.2. Describe the function of  colorful  ingredients of  cement. 

Answer  Functions of Cement Manufacturing ingredients  1. Lime( CaO)  Lime forms nearly two- third(2/3) of the cement.  ii. Sufficient  volume of lime forms di- calcium silicate( C2Si O2) and tricalcium  silicate in the manufacturing of cement.  iii. Lime in  redundant, causes the cement to expand and disintegrate.  2. Silica( SiO2)  i. The  volume of silica should be enough to form di- calcium silicate  C2SiO2) andtri-calcium silicate in the manufacturing of cement.  ii. Silica gives strength to the cement.  iii. Silica in  redundant causes the cement to set  sluggishly.  3. Alumina( Al2O3)  Alumina supports to set  snappily to the cement.  Cement product & summations 1 – 4 D( CE- Sem- 5)  ii. It also lowers the clinkering temperature.  iii. Alumina in  redundant reduces the strength of the cement.  4. Iron Oxide( Fe2O3) Iron oxide gives colour to the cement.  5. Magnesia( MgO)  i. It also helps in giving colour to the cement.  ii. Magnesium in  redundant makes the cement unsound.  6. Calcium Sulphate( or) Gypsum( CaSO4) At the final stage of  manufacturing, gypsum is added to increase the setting of cement.   

Que1.3. What are Bogue’s  emulsion of portland cement? Also  give its  parcels. 

Answer  Bogue’s emulsion of Cement Following are the  colorful Bogue’s   emulsion of cement  1. Calcium Silicates  Alite or 3CaO. SiO2 or C3S  It’s responsible for early strength.  First 7 days strength is due to C3S.  c. It produces  further heat of hydration.  d. A cement with  further C3S content is better for cold rainfall concreting.  ii. Belite or 2CaO. SiO2 or C2S  a. The hydration of C2S  thresholds after 7 days. Hence it gives strength after  7 days.  C2S hydrates and hardens  sluggishly and provides much of the ultimate  strength.  It’s responsible for the after strength of the concrete.  d. It produces  lower heat of hydration.  2. Calcium Aluminates  Aluminate or 3CaO. Al2O3 or C3A  a. The  response of C3A with water is  veritably  presto.  b. It may lead to an immediate stiffening of paste, and it’s called flash set.  To  help this flash set, 2- 3 gypsum is added at a time of grinding  cement clinker.  d. The doused  C3A don’t contribute to the strength of the concrete.  Low C3A for sulfate resistance Cement.  ii. Ferrite or 4CaO. Al2O3. Fe2O3 or C4AF  C4AF hydrates  fleetly.  Concrete Technology 1 – 5 D( CE- Sem- 5)  b. It doesn’t contribute to strength of the concrete.  Controls the color of cement.  3. Gypsum is added to avoid the  unbridled setting performing from C3A   response with water.  

Que1.4. Explain manufacturing processes of the cement with  neat  illustration. Give comparison between wet and dry process of  manufacturing. 

Answer  Manufacturing Processes Following are the  way of  manufacturing of cement  Make disasters In this step, the raw material is converted into fine  greasepaint and it’s done by following two processes  1. Dry Process  i. In this process calcareous material  similar as limestone( calcium  carbonate) and argillaceous material  similar as  complexion are base independently  to fine greasepaint in the absence of water and  also are mixed together in  the asked  proportions.  ii. Water is  also added to it for getting thick paste and  also its  galettes are  formed, dried and burnt in kilns.  iii. This process is  generally used when raw accoutrements  are  veritably strong and  hard.  iv. In this process, the raw accoutrements  are changed to powdered form in the  absence of water.  2. Wet Process  i. In this process, the raw accoutrements  are changed to powdered form in the  presence of water.  ii. In this process, raw accoutrements  are pulverized by using a ball  shop, which  is a rotary  sword cylinder with hardened  sword balls.  iii. When the  shop rotates,  sword balls pulverize the raw accoutrements  which  form slurry( liquid admixture).  iv. The slurry is  also passed into  storehouse tanks, where correct  proportioning is done.  Proper composition of raw accoutrements  can be assured by using wet  process than dry process.  vi. This process is generally used when raw accoutrements  are soft because  complete mixing isn’t possible unless water is added.  vii. Corrected slurry is  also fed into rotary kiln for burning.  The  factual purpose of both processes is to change the raw accoutrements  to  fine greasepaint.  Burning  Corrected slurry is feed to rotary kiln, which is a 150- 500  bases long, – 16  bases in periphery and temperature arrangement is over to  1500- 1650 °C.  ii. At this temperature slurry losses  humidity and forms into small lumps,  after that changes to  disasters.  iii. disasters are cooled in another inclined tube  analogous to kiln but of  lower  length.  Grinding  i. Now the final process is applied which is grinding of clinker, it’s first  cooled down to atmospheric temperature.  ii. Grinding of clinker is done in large tube  manufactories. After proper grinding  gypsum( Calcium sulphate CaSO4) in the  rate of 01- 04 is added for  controlling the setting time of cement.  iii. Eventually, fine ground cement is stored in  storehouse tanks from where it is  drawn for quilting.  

Que1.5. Explain the  colorful types of cements. 

Answer  Following are the  colorful types of cements  1. humidity content of the slurry  is 35- 50.  2. Size of the kiln  demanded to  manufacture the cement is  bigger.  3. The  quantum of heat  needed  is advanced, so the  needed energy   quantum is advanced.  4. lower  provident.  5. The raw accoutrements  can be  blend   fluently, so a better  homogeneous material can be   attained.  6. The  ministry and  accoutrements  don’t need  important   conservation.  humidity content of the  bullets  is 12.  Size of the kiln  demanded to  manufacture the cement is   lower.  The  quantum of heat  needed is  lower, so the  needed energy   quantum is lower.  further  provident.  delicate to control the mixing  of raw accoutrements  process, so it  is  delicate to  gain  homogeneous material.  The  ministry and  accoutrements  need  further   conservation.  1. Sulphate defying Cement  i. In this cement, the chance of tricalcium aluminate C3A is kept  below 5 and it results in the increase in  defying power against  sulphates.  2. Rapid Hardening Cement  i. The  original and final setting times of this cement are same as those of  ordinary cement. But it attains high strength in early days.  ii. It contains high chance of tricalcium silicate C3S to the extent of  about 56.  3. White Cement  White cement is prepared from  similar raw accoutrements  which are  virtually  free from colouring oxides of iron, manganese or chromium.  ii. It’s white in colour and is used for  bottom finish, cataplasm work,  garnishment  work,etc.  4. Coloured Cement  i. The cement of asked  colour may be  attained by  privately mixing  mineral  colors with ordinary cement.  ii. The  quantum of coloring material may vary from 5 to 10.  iii. These types of coloured cement are extensively used for finishing of  bottoms,  external  shells, artificial marble, window stave crossbeams, textured panel  faces, stair treads,etc. . Color Colour  1. Chromium Oxide herbage  2. Cobalt Imparts Blue  3. Iron Oxide in different proportion Brown, Red, Yellow . Manganese Dioxide Black or Brown  5. Pozzolana Cement  Pozzolana is a  stormy greasepaint.  ii. This type of cement is used to prepare mass concrete of  spare  blend and  for marine structures.  iii. It’s also used in sewage  workshop and for laying concrete under water.  6. Hydrophobic Cement  It’s manufactured by grinding ordinary portland cement clinker with  to0.4 of oleic acid, stearic acid or pentachlorophenol.  ii. This addition forms water repellent film around each  flyspeck by the   humidity content of atmosphere.  iii. When concrete is prepared using this cement, the water repellent film  breaks out which improves the plasticity of concrete.  7. Quick Setting Cement  i. When concrete is to be laid under water, quick setting cement is to be  used.  ii. This cement is manufactured by adding small chance of aluminum  sulphate( Al2SO4) which accelerates the setting action.  iii. The setting action of  similar cement starts with in 05  twinkles after  addition of water and it becomes gravestone hard in  lower than half an hour.  8. Low Heat Cement  i. In this cement the heat of hydration is reduced by tricalcium aluminate  C3A) content.  ii. It contains  lower chance of lime than ordinary portland cement.  iii. It’s used for mass concrete works  similar as  headsetc.  9. High Alumina Cement  1. This cement contains high aluminate chance  generally between 35-  55.  2. It gains strength  veritably  fleetly within 24 hours. It’s also used for  construction of  heads and other heavy structures.  3. It has resistance to sulphates and action of frost also.  10. Air Entraining Cement  1. Air enplaning  cement is produced by grinding  nanosecond air enplaning   accoutrements  with clinker or the accoutrements  are also added independently while  making concrete.  2. Entrainment of air also improves plasticity and  continuity. It’s  set up  that entrainment of air or gas bubbles while applying cement, increases  resistance to frost action.  3. It’s recommended that air contents should be 03- 04 by volume.  Natural resins, fats, canvases  are used as air enplaning  agents.

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