
What is cement?
Cement is often mixed with other materials to create concrete structures, which are composite materials that combine a binder (cement paste) with filler particles. Concrete is made by mixing cement with sand, crushed rock, and water, which creates a fluid slurry that can be poured and molded into shape. Over time, the concrete hardens and gains high compressive strength, but it is weak in tension, so reinforcement is often added. Concrete structures can be used for load-carrying capacity, radiation shielding, and leak tightness.
Cement is an important building material. It is manufactured through closely controlled chemical combination of Calcium, Silicon, etc. Having a clear concept around Cement Ingredients which is an important building material will help you in various exams like SSC JE, and other Junior Engineer or State level examinations. Read this article Cement Ingredients and function to get some important questions that were asked in SSC JE CE 2017 exam and align your preparation strategy accordingly.
There are general eight major ingredients of cement. The percentage of these ingredients is given below:
S.No Ingredient Chemical form Percentage (%)
1. Lime Cao (62-65)%
2. Silica SiO2 (17-25)%
3. Alumina Al2O3 (3-8)%
4. Calcium Sulphate CaSo4 (3-4)%
5. Iron Oxide Fe2O3 (3-4)%
6. Magnesia MgO (1-3)%
7. Sulphur S (1-3)%
8. Alkalies Na2O, K2O (0.2-1)%
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Cement Ingredients and Functions:
Below is the details given about all the ingredients present in Cement. Go through the functions and make notes for SSC JE CE exam.
Lime: The function of lime is that it is the main constituent for manufacturing of cement which imparts cementing property to cement. Lime imparts strength and soundness to the cement. If it is present in excess quantity, it makes the cement unsound (causes it to expand and disintegrate). Deficiency of lime in cement reduces it strength and causes it to set quickly.
Silica: Function of Silica in cement is that it imparts strength to the cement. It undergoes chemical reaction with calcium to form dicalcium silicate (C2S) and tricalcium silicate (C3S). Silica if Present in excess form adds strength to the cement but simultaneously reduces the strength to cement.
Alumina: It imparts quick setting property to the cement. It acts as a flux and lowers the clinkering temperature. Alumina in excess quantity reduces the setting time of cement but simultaneously reduces the strength of cement.
Calcium Sulphate: It is present in the form of Gypsum in the cement (CaSo4.2H2O). Gypsum retards the setting of cement i.e it increases the setting time of cement.
Iron Oxide: It imparts colour to the cement. It also gives hardness and strength to the cement.
Magnesia: It also gives colour to the cement. Magnesia in excess makes the cement unsound.
Sulphur: A very small quantity of Sulphur in the cement makes the cement sound.
Alkalies: The most of the alkalies present in raw materials are carried away by the flue gases during heating and the cement contains only a small amount of alkalies. If they are in excess in cement, they cause a number of troubles such as alkali-aggregate reaction, efflorescence and staining when used in concrete, brickwork or masonry mortar.
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