UNIT 1 - Cement types basics properties n
- 3. Suppose, the length and height of the 4 inches wall = 10 feet It is assumed that in a 4 inches brick wall, total numbers of required bricks = 500 It is known that in one bag cement, the total numbers of bricks = 250 (for 4 inches wall) The thickness of mortar = ½ inch. Rs. 350/- to 500/-
- 4. The word cement has come from the roman word ‘OPUS CAEMENTICIUM A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together.
- 5. Before the 18th century • Cement made with lime, sand, and gravel was used. • Examples: Dome of Pantheon of Rome, Baths of Caracalla 18th, 19th, and 20th centuries • Portland cement patented by Joseph Aspdin • Blend of Rosendale and synthetic cement 21 st century and future… • OPC most common. Base of concrete, mortar, grout • Green Cement made by recycled coal, ash, bio-mass, mine tailings, etc.
- 6. Physical Gives strength to masonry Excellent binding material Easily workable Stiffens early Possesses good plasticity Offers good resistance to the moisture Fineness Soundness Alumia: Iron oxide ≥ 0.66 0.66≤Lime saturation factor ≤1.02 Sulphur content ≤ 2.75 % Wt. of insoluble residue ≤ 1.5% Chemical
- 7. It is quite important to maintain the composition of cement because all the functions of every type of cement depends on individual quantity of every component. LIME 62-72% SILICA 17-25% ALUMINA 3-8% SULPHUR 1-3 % ALKALIES 0.2-1 % MAGNESIA 1-3 % IRON OXIDE 3 – 4 % CALCIUM SULPHATE 3-4%
- 8. •Controls strength and soundness LIME (CaO) •Gives strength, excess quantity causes quick setting •Quick setting, excess lowers strength SILIC A (SiO2 ) Alumina (Al2 O3 ) •Form of Gypsum. It increases the initial setting time. Calcium Sulphate (Ca SO4 )
- 9. •Imparts color, hardness & strength helps in fusion of ingredients IRON OXIDE (Fe2 O3 ) •In small amount imparts color and hardness, excess causes cracking Magnesium Oxide (MgO) •It makes the cement sound. Sulphur Trioxide (SO3 ) •It makes the cement sound. Alkalies
- 10. Demerits Merits
- 11. The chemical reaction which takes place between cement and water is known as hydration of cement. This reaction is exothermic in nature, which means heat is released during the reaction, and the evolved heat is called as heat of hydration. Hydration of cement Hence, it binds the aggregates together. Anhydrous cement (unhydrated cement) does not bind with fine or coarse aggregates. Adhesive property is gained by cement only after hydration.
- 13. Limestone is brought from mines Limestone is crushed Some additives are added at this stage Mixture is grinded to form homogeneous mixture Formation of clinker at high temperature Suitable are additives are added and again grinded This yields cement Manufacturing of cement
- 15. MIXING OF RAW MATERIALS BURNING GRINDING CEMENT IS PRODUCED & SENT FOR PACKING
- 16. Manufacture of Ordinary cement Limestone or Chalk & Clay is mixed either by dry or wet condition. Which is otherwise known as Dry or Wet process. Dry Process (Modern Technology) Wet Process (Old Technology) (1) MIXING OF RAW MATERIALS
- 17. (A) DRY PROCESS In this process calcareous material such as lime stone (calcium carbonate) and argillaceous material such as clay are ground separately to fine powder in the absence of water and then are mixed together in the desired proportions. Water is then added to it for getting thick paste and then its cakes are formed, dried and burnt in kilns. This process is usually used when raw materials are very strong and hard. In this process, the raw materials are changed to powdered form in the absence of water.
- 19. (B) WET PROCESS: In this process, the raw materials are changed to powdered form in the presence of water. In this process, raw materials are pulverized by using a Ball mill, which is a rotary steel cylinder with hardened steel balls. When the mill rotates, steel balls pulverize the raw materials which form slurry (liquid mixture). The slurry is then passed into storage tanks, where correct proportioning is done. Proper composition of raw materials can be ensured by using wet process than dry process. Corrected slurry is then fed into rotary kiln for burning.
- 20. (b) Wet Process: Continued------ This process is generally used when raw materials are soft because complete mixing is not possible unless water is added. Actually the purpose of both processes is to change the raw materials to fine powder. Wet process is stopped and after 1980 Dry process is followed.
- 22. Burning & Grinding Operations
- 23. (2) Burning: Corrected slurry is feed to rotary kiln, which is a 150-500 feet long, 8-16 feet in diameter and temperature arrangement is up to 1500- 1650 degree C. At this temperature slurry losses moisture and forms into small lumps, after that changes to clinkers. Clinkers are cooled in another inclined tube similar to kiln but of lesser length.
- 25. (3) Grinding: Now the final process is applied which is grinding of clinker, it is first cooled down to atmospheric temperature. Grinding of clinker is done in large ball mill. After proper grinding gypsum (Calcium sulphate Ca SO4) 2-3 % is added for controlling the setting time of cement. Finally, fine ground cement is stored in storage tanks from where it is drawn for packing.
- 26. Vertical Section of Ball Mill The Steel balls are grounded and crushed. The crushed material passes through an inner sieve plate and collected from an outlet.
- 27. • SHOULD BE FAVOURABLE AND SUITABLE FOR THE SETTING AND HARDENING CLIMAT E • SHOULD BE EASILY AVAILABLE AND ECONOMICAL LABOU R • SHOULD BE NEAR . WILL DECREASE COST OF TRANSPORT MARKE T • EASILY AVAILABLE. CONTINUOUSLY AVAILABLE AROUND SITE. RAW MATERIALS • EASILY AVIALBLE FOR RAW MATERIALS AND FINISHED MATERIALS. TRANSPOR T
- 28. The Indian cement industry is the 2nd largest market after China accounting for about 8% of the total global production. Housing sector is the biggest demand driver of cement(67%) followed byinfrastructure (13%), commercial construction (11%) and industrial construction (9%).
- 29. Andhra Pradesh is the largest producer of cement in India followed by Rajasthan and Tamil Nadu. SATNA, cement city, in MP, is in the limestone belts of India. As a result, it contributes around 8%–9% of India's total cement production. India is producing different varieties of cement like ordinary Portland cement, Oil well cement, sulphate resisting cement, white cement etc. Production of these varieties conform to BIS standards.
- 30. • UNIFORM • GREENISH GREY COLOR • FEEL SMOOTH. IF ROUGH; ADULTERATION OF SAND • HAND IN BAG SHOULD FEEL COOL NOT WARM • EARTHY SMELL IF TOO MUCH CLAY OR SILT ADULTERANT • SHOULD BE FREE FROM ANY HARD LUMPS PHYSICAL PROPERTIE S • Thick paste of cement made on thick glass and kept underwater for 1 day. Should set and not crack! STRENGT H https://www.youtube.com/watch?v=6V8Yc0ulVO8
- 31. LABORATORY TEST FOR CEMENT ❑ Fineness Test, ❑ Consistency test ❑ Setting Time Test ❑ Compressive strength test ❑ Soundness Test
- 32. (1) Fineness Test: This test is carried out to find proper grinding of cement. The fineness is tested by: By Sieve analysis: Break with hands any lumps present in 100 grams of cement placed in IS sieve No.9 and sieve it by gentle motion of the wrist for 15 minutes continuously. The residue when weighed should not exceed 10 percent by weight of the cement sample. https://www.youtube.com/watch?v=eP8_yrP8xc0
- 33. (2) Consistency Test : This test is performed to determine the amount of water content required to produce cement paste to produce a cement paste of standard or normal consistency. Vicat apparatus is used for performing this test. • 300 g of cement is mixed with 25 per cent water. • The paste is filled in the mould of Vicat’s apparatus and the surface of the filled paste is smoothened and levelled. • A square needle 10 mm x 10 mm attached to the plunger is then lowered gently over the cement paste surface and is released quickly. The plunger pierces the cement paste. • After releasing wait for min 3 sec to take reading. • Penetration result reading is noted. • Penetration b/t 5mm to 7 mm from bottom of the mold. The amount of water added is considered to be the correct percentage of water for normal consistency. https://www.youtube.com/wat ch?v=YphaFzfiNMg
- 34. The term setting implies solidification of the cement paste. The initial setting time The time taken by the paste to stiffen to such an extent that the Vicat’s needle is not permitted to move down through the paste to within 5 ± 0.5 mm measured from the bottom of the mould. The final setting time The time after which the paste becomes so hard that the angular attachment to the needle, under standard weight, fails to leave any mark on the hardened concrete. • When water is added to cement, the resulting paste starts to stiffen and gain strength and lose the consistency simultaneously. • Initial and final setting times may be regarded as the two stiffening states of the cement. • The beginning of solidification, called the initial set, marks the point in time when the paste has become unworkable. • The time taken to solidify completely marks the final set, which should not be too long in order to resume construction activity within a reasonable time after the placement of concrete. (3) Setting Time Test: https://www.youtube.com/watch?v=qYIh43yzBWQ
- 35. (4) Compressive Strength test of Cement: This test is very important to determine the compressive strength. In this test, three moulds of (face area 50 cm2) are prepared and cured under standard temperature conditions and each cube tested by placing it between movable jaws of the compressive strength testing machine. The rate of increasing load is zero in the beginning and varies at 350 kg/cm2 per minute. The load at which the cube gets fractured divided by the cross sectional area of the cube, is the compressive strength of the cube. The average of the compressive strengths of three cubes is the required compressive strength of the cement sample.
- 36. The purpose of this test is to detect the presence of excess lime in cement. Soundness of cement may be tested by Le- Chatelier method. It is a very important test to assure the quality of cement since an unsound cement produces cracks, distortion and disintegration, ultimately leading to failure. (5) Soundness Test: The mould is placed on a glass sheet and is filled with neat cement paste formed by gauging 100 g cement with 0.78 times the water required to give a paste of standard consistency. The mould is covered with a glass sheet and a small weight is placed on the covering glass sheet. The mould is then submerged in the water at temperature of 27°-32°C. After 24 hours, the mould is taken out and the distance separating the indicator points is measured. The mould is again submerged in water. The water is now boiled for 3 hours. The mould is removed from water and is cooled down. The distance between the indicator points is measured again. The difference between the two measurements represents the unsoundness of cement. This should not exceed more than 10mm. https://www.youtube.com/watch?v=je5ztHs9tII
- 37. TYPES OF CEMENT
- 38. 1. ACID RESISTANT CEMENT: • Used in chemical industry for acid and heat resistance coating of installations. • It is not water resistant and fails when attacked by water. • Linseed oil is added to increase resistance to water. 2. BLAST FURNACE CEMENT: • Slag obtained from blast furnace is used. • Slag from manufacture of pig iron. • Not suitable in dry arid zones. • Requires longer curing period • Cement is durable. 3. COLOURED CEMENT: • Used for finishing if floors, artificial marble, window sill, stair treads. • Mixing mineral pigments with ordinary cement. 4.HIGH ALUMINA CEMENT: • Sets soon & high strength • Can withstand high temperature • Resist acids.
- 39. 5. POZZOLANA CEMENT: • It has good compressive strength. • Resist action of sulphates to certain extent. • Less heat during setting • Watertight and cheap • Used in marine structures, sewage works, canals & dams, bridge piers & structures near sea shore. 6. QUICK SETTING CEMENT: • Setting action in 5 mins. • Becomes hard like stone in less than 30 mins • Used with concrete under static water or running water. 7. RAPID HARDENING CEMENT: • Same as ordinary cement • High strength in early days • Construction can be carried quickly. • Formwork can be removed earlier. • Not damaged easily. • Short curing period.
- 40. 8. WHITE CEMENT: • High strength • Aesthetic value • Used in swimming pools, sculptures, etc • Used for fixing marbles and tiles. 9. SULPHATE RESISTING CEMENT: • Ordinary cement is subject to attack of sulphate. • Used for foundations/basements where soil contains sulphates • Marine construction • Pile fabrication in marshy or sulphate bearing soils. • Canal linings, culverts etc
- 50. To understand sand and cement required for plastering we should remember: The ratio of cement and sand should be 1:5.