We all are living on Earth. In this world, to live a better life we need three most important things. These things are Food, Cloths, and Home. Among those three things, Home is the most important thing. But have you ever thought what is most important that helps to make our home, building, or any other structure? Your answer will be sand, stone, bricks, concrete, steel water, etc. But one thing, which bonds all materials together that thing is Cement. In our daily life, cement has a very important role. We live in the house, walk on the road, travel through bridges. Every building, road, airport, and many structures cement is required for construction.
But did you think that Cement comes from where? What is cement made of? How it manufactures? Let, we will talk about all related topics to cement.
What is Cement?
A cement is a binding substance, which used to bind other buildings or civil construction material like bricks, stones, gravels, tiles and, etc. Cement can set and hardened independently and can bind other building materials together. It is a very fine powder contains limestone, clay, silica, and alumina. Also contained with bauxite and iron oxide. All these contents blended and heated to 1200° C to 1500° C, this process makes clinker. Then ground this clinker into fine powder. Also added Gypsum for providing settle time.
History of Cement:
Human has started the use of cement material with construction has been started. Even we can also say that cement material history is old as like engineering construction history. The archaeologist has discovered some kinds of cement material used in Harappa and Mohanjo-Daro civilization during excavation. In the earlier Greeks and Romans had used burning limestones as cementing materials. Later they had increased awareness of volcanic ash and tuff, mixing with limestone powder and sand, which provides better strength and durability in water.
Romans had found volcanic tuff near Pozzuoli village in Italy. The obtained ash contained better siliceous, due to this natural quality this named as Pozzolana. Later, this name added to other artificial and natural cement materials also, having similar properties.
Accidently Romans had discovered by adding blood in cement mixture will increase durability and workability. Hemoglobin having better plastic property. It was another reason for the durability of Roman structures.
William Aspdin had invented “Modern portland cement”. And patented on 21st October 1824.
China is the World’s largest cement producer country. 2200 Million Metric Tonnes of cement produced in 2019. Over half of the cement is produced in China.
India is the World’s second-largest cement producer country. 320 Million Metric Tonnes of cement produced in 2019.
World’s largest cement plant is in Michigan. Currently, this plant is the part of the world’s largest producer company Lafarge Corporation.
Do you know???
The world’s tallest statue “Statue of Unity” is situated in Gujarat, Bharat (India). This statue is built to tribute to “Iron man of India – Sardar Vallabh Bhai Patel. This statue is 30 meters taller than the previous record-holder statue “Spring Temple Buddha” in China. To construct the Statue of Unity, 210,000 m³ cement used.
Types of Cement:
There are various types of cement to fulfill specific requirements in construction industries. These types are based on the use of additives, various types of raw material in mixture, and variation in chemical composition.
- Ordinary Portland Cement – Grade 33, Grade 43, Grade 53.
- Rapid Hardening Cement –
- Extra Rapid Hardening Cement
- Sulphate Resisting Cement
- Portland Slag Cement
- Quick Setting Cement
- Super Sulphated Cement
- Low Heat Cement (Fly ash based cement)
- Portland Pozzolana Cement (Calcined clay-based cement)
- Air Entraining Cement
- Coloured Cement (White Cement)
- Hydrophobic Cement
- Masonry Cement
- Expensive Cement
- Oil Well Cement
- Rediset Cement
- Concrete Sleeper Grade Cement
- High Alumina Cement
- Very High Strength Cement
Portland cement are classified under the ASTM (American Society for Testing Materials) standards. According to ASTM, cement having Type I, Type II, Type III, Type IV, Type V some other minor types.
Main stages of Cement making:
To make the cement in a cement production plant, there is a standard process. In the first step of the process is to quarrying and raw materials are prepared. In the second step, the mixing of raw material (clay and limestone) in a certain proportion. Then this mixture burned OR heated in a furnace (kiln) to make clinker at a temperature of about 1300° to 1500° C. This step is known as the clinker production step. And in the third stage, this clinker cooled and mixing with gypsum then ground into a fine powder which is the final product as cement. Let, we will see a cement production process on a flow chart. Before it, also we need to get familiar with types of cement processes.
Types of Cement processes:
Here are the three main types of cement processes. i.e,
- Wet Process
- Dry Process
- Semi-dry or Precalcinar Process
In the wet process, the limestone is brought from the quarry and crushes into a small form. Then it mixed with clay and ground into fine powder in a ball mill or tube mill. And mixed it with water. This makes a fine consistency slurry. The slurry is pumped into a slurry tank. To prevent the settling of limestone and clay particles, the slurry is stirred with a rotating arm or chain in slurry tanks.
This slurry sprayed on kiln’s outer surface. The heated kiln surface removes moisture contents from slurry and converts into flakes. These flakes go to the hottest part of the kiln. Where temperature ranges from 1300° to 1500° C. At this temperature material gets diffused. And chemical reactions occur in diffusion. Where, the silica, alumina, and lime get combined. This combination turns into a grain size of 3 to 20 mm known as clinker. The cooled clinker fine ground in a ball mill with mixing gypsum into. Now, it is ready for packaging.
The main advantage of the wet process is, it is more accurate and easy in controlling the mixing and grinding raw materials. But, it requires huge fuel to remove water content from the slurry.
In the dry process, the raw materials are ground in a grinding mill and charge it in the correct proportion. This raw material mixture is ground in very fine powder in the grinding mill. This fine powder is the raw meal. And it further ground and mixing of the corrected amount of its contents by pressurized air. And this powder also contained dry air, it behaves like a fluid.
Now, this blended powder filtered and fed into granulator. Here, 12 percent by weight of water added in fine powder to make small pallets. It helps in chemical reaction while heating in a rotary kiln. In the dry process fuel (coal) is required lesser then wet process. So, it is an economical process.
For the semi-dry process, the same method used. In the semi-dry process also required less amount of fuel (coal). It allows for a higher production rate.
In this article, we have studied Cement, history, types, manufacturing process, and process types. We will discuss in detail about cement manufacturing plant and machineries in the next article.
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