Question

what are raw materials and types of cement in industry of cement?

in 800 words or more (please no less), i don't want an intro about cement.

Answer 1

Raw materials- The raw materials which required to produce cement are calcareous materials such as lime stone or chalk, and argillaceous material such as shale or clay. Cement industries are established where raw materials are available in plenty. The process of manufacturing of cements includes grinding of raw materials, mixing them and burning them in a kiln at a temperature about 1300-1500°C. At this temperature the material fuses to form nodular shaped clinker. Clinker is cooled and ground to fine powder with addition of about 3-5℅ of gypsum. The product formed after this process is cement.

Now the followings are the materials and their composition in cement-

Lime..............60- 67%

Silica...............17- 25%

Alumina...........3- 8%

Iron oxide.........0.5- 6%

Magnesia..........0.1- 4%

Alkalies............. 0.4- 1%

Sulphuric anhydride......1.3- 3%

These oxides interact which each other in the kiln at high temperature to form complex compounds.

Types of cement- The followings are the types of cements-

1. Ordinary Portland cement- It is most important type of cement. Most of the structures are made with the help of this cement. It is possible to upgrade the quality of cement by using high quality limestone , modern equipments, closer on line control of construction, maintaining better particle size distribution, finer grinding and better packing.
2. Rapid hardening cement- This cement is similar to Portland cement, but one properties that make differ it from OPC is it develops rapidly and as such it may be more appropriate to call it as high early strength cement. It is generally used for pre fabricated concrete construction.
3. Sulpher resisting cement- Sulphates react both with the free calcium hydroxide in cement to form calcium sulphate and with hydrate of calcium aluminate to form calcium sulphoaluminate. It is uses to protect structure from sulpher attack.
4. Quick setting cement- The early setting property is brought by reducing the gypsum content at the time of clunker grinding. This cement is required to be mixed, placed and compacted very early.
5. Low heat cement- When cement is mixed with water then it produces heat and this cement is used to reduce the heat of cement.
6. Portland pozzolona cement- Pozzolona is a material which replace some raw material of cement by maintaining its properties. Portland ppzzolona cement produces less heat of hydration and offers greater resistance to attack of aggressive waters than ordinary portland cement.