How Cement is Made
Cement is manufactured through a closely controlled chemical combination of calcium, silicon, aluminium, iron and other ingredients.
Common materials used to manufacture cement include limestone, shells, and chalk or marl combined with shale, clay, slate, blast furnace slag, silica sand, and iron ore.
When These ingredients, heated at high heat, form a rock-like substance that is floor into the fine powder that we usually consider as cement.
Also, read: What Is Cement | Type of Cement
Various Types of cement ingredients and their work areas are given below,
- Silicon Dioxide (Silica)
- Calcium Oxide (Lime)
- Calcium Sulphate
- Aluminum Oxide (Alumina)
- Iron Oxide
- Magnesium Oxide
1. Silicon dioxide (Silica):
- It is also a major vital ingredient of cement.
- It is familiar to silica.
- It clutches 19-23% of cement mass.
- It is chemically articulated by SiO2.
- Function: The purpose of silica is also to give strength to cement.
2. Calcium Oxide (Lime):
This is the main content of the cement manufacturing process or at the top of the list of the main ingredient of cement.
Calcium Oxide has 61% to 67% of the mass of cement, which is holding the highest percentage among all others.
Shortly it has known CaO. Generally, the calcium Oxide familiars as lime.
The function of this: It gave cement sound and provided inner boding strength to cement.
3. Calcium Sulphate:
CaSO4 is chemically composed of it. This Fixing is in the form of gypsum, and its function is to increase the initial setting time of cement.
Function: It assists in raising the initial setting time of cement.
4. Aluminium oxide (Alumina):
- It is a known alumina. The chemical name is AI2O3.
- Cement contains its 2% – 6% alumina of its mass.
- This ingredient imparts quick functioning correctly to cement.
- Express alumina weakens the cement.
- Function: It works on a quick-setting property to cement.
The majority of the alkalies within raw material are carried away from the flue gases through heating, and only a small quantity will be abandoned.
If they’re in excess in cement, efflorescence is caused.
A very little quantity of it may present in the cement.
6. Iron Oxide:
- It is also known as Ferric Oxide.
- Cement has 0.5%-6% iron oxide of its mass.
- Iron Oxide’s chemical name is Fe2O3.
- Function: It has to prove color and hardness to cement.
- It also gave enough strength to cement.
7. Magnesium Oxide:
Magnesium Oxide is articulated by MgO. It provides color and hardness to cement.
- It is familiar to Sulphur.
- It clutches 1.5%-4% of the mass of cement.
- The chemical name of Sulphur is S.
- Function: A very little quantity of Sulphur in the cement makes it (Cement) sound.
History of Cement
Bricklayer of cement Mr.Joseph Aspdin of Leeds from England first made portland cement near the beginning in the 19th century by burning powdered limestone and clay in his personal kitchen stove.
By this crude technique, he had laid the groundwork for an industry that annually processes mountains of limestone, cement rock, clay, and other materials factually into a powder so fine it will go by a sieve able of holding water.
The cement plant laboratories check each move in the manufacture of portland cement by frequent chemical and physical tests.
The labs also analyze and test the completed product to ensure that it complies with all industry stipulation on all weather conditions.
Manufacturer of cement
The most familiar way to manufacture portland cement is through a dry process. The primary step is to dig up the principal raw materials, chiefly limestone, clay, and extra materials.
After digging up the rock is crushed. This involves various stages. In the initial first stage, crushing reduces the rock to a maximum size of about 6 inches.
The rock then moves toward secondary crushers machine or hammer mills for a decrease to about 3 inches or lesser.
The crushed rock is amalgamated with other ingredients such as iron ore, fly ash, and ground, mixed, and fed to the cement kiln.
The cement kiln gave heats to all the ingredients around about 2,700 degrees Fahrenheit in enormous cylindrical steel rotary kilns lined with special firebrick.
Kilns are normally as much as 12 feet in diameter—large enough to put up an automobile and longer in many instances than the top height of a 40-story building. The large kilns are mounted with the axis inclined from the horizontal.
The finely grinded raw material or slurry is fed into the higher end. On the other hand,the lower end is a roaring blast of flame, produced by specifically controlled burning of the contains like powdered coal, oil, alternative fuels, gas under forced draft.
When the material moves through the kiln, certain elements are driven off in the form of gases. The remaining elements after burning bond to form a new substance known as clinker.
The Clinker comes out of the kiln as grey balls, its size about of marbles.
The Clinker is released red-hot from the lower base end of the kiln, and usually, it is brought down to managing temperature in diverse types of coolers.
The heated air from the coolers comes back to the kilns, a method that saves fuel and increases burning efficiency.
Afterward, the clinker is cooled, and cement plants grind it where it mixes with small amounts of limestone and gypsum. Cement is too fine, for example,1 pound of cement contains 150 billion grains.
Finally, the cement is ready for transport to ready-mix concrete companies to be habitual in a multiplicity of construction projects.
At the end of this process, the dry process is the most contemporary and prominent way to produce cement, some kilns in the United States apply a wet process.
These two methods are basically alike except in the wet process. The basic materials are ground with water before being fed into the kiln.