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.