Information on Cement

What is Cement?

Cement is backbone of the construction industry. Cement is a core binding substance employed in the construction of buildings, roads, bridges, pipes, and numerous other utilities. When it sets, it combines the other raw materials tightly together.

A variety of materials are required to manufacture cement. These include gypsum, clay, sand, fly ash metric, silica, limestone, iron ore, and others. Limestone is the key ingredient of cement and in most cases it can be mined on site. Surrounding quarries are good sources to mine the other raw materials of the cement manufacturing process.

As environmental protection has gained considerable attention today, the raw materials for producing cement have accordingly been modified. Besides the conventional natural ingredients, industrial by-products have also begun to be used to produce cement. This is a crucial step towards achieving sustainable development without hindering progress.

Difference between Cement and Concrete

Cement is a grayish substance that is ground to a fine powder. When wet, it hardens and binds the other raw materials such as sand and gravel used in construction together. The binding process involves several chemical reactions that are highly complex. The materials absorb water and a crystallization process takes place that combines them together.

Concrete refers to the aggregate combination of cement and other raw materials. After these ingredients have been closely combined, they should be soaked in warm water to improve the setting.

Types of Cement

There are several types of cement. The most popular ones are:

Ordinary Portland Cement (OPC) 43
Ordinary Portland Cement (OPC) 53
Portland Pozzliano Cement (PPC)
Slag Cement

1. Ordinary Portland Cement (OPC) 43 or 53

OPC is the most common cement that is used today. It comprises of a mixture of finely powdered gypsum and Portland clinker. Portland clinker and a limited quantity of calcium sulfates are ground together to created a fine powder, which is Portland cement.

Non-specialty grout, stucco, concrete, and mortar form the basic constituents of this type of cement, and these ingredients account for the cement's popularity. Portland cement is produced in 2 grades—43 and 53.

2. Portland Pozzolano Cement (PPC)

When Ordinary Portland Cement and Pozzolana materials (fly ash and others) are combined in proportions in the range of 15-35% weight of cement, Portland Pozzolana Cement is obtained.

3. Slag Cement

Slag cement is produced from the byproducts of the iron production process. These are the steps involved in producing slag cement:

Slag cement is obtained when iron is manufactured using a blast furnace.
Molten iron and molten slag collect at the bottom of the furnace.
The molten slag is separated and transferred to a granulator where a process called granulation takes place.
During granulation, the molten slag is converted into granules by soaking it with water.
These granules are cooled very quickly to prevent them from crystallizing.
Finally, the granules become glassy and metallic.
They are dried and finely ground to form slag cement.

Information on a Cement Bag

This is the information that buyers have to verify while they are purchasing a bag of cement:

First check the type of cement. OPC 43 / OPC 53 / PPC / Slag Cement.
Net mass of cement
Name of the manufacturer
Trademarks, if any
IS Certification Mark, if any
Week and year of packaging
Maximum Retail Price (MRP) in case of trade bags only. No MRP would be found on NFR (Not for Resale bags). MRP bags are generally used for resale for eg: Manufacturers to Authorized Dealers to Retailers and then to end consumers whereas, NFR bags are not meant for resale and to be used directly by end consumers like contractors, builders, construction firms, etc… Process would be: Manufacturers to end consumers through Authorized Dealers.

Useful Hint:
Frame Structure: Up to 7 storeys - cement consumption is 0.40 bag (50kg*40% = 20 kg) per sq ft of construction & 0.45 bag (50kg*45% = 22.5 kg) for the structure above 7 storeys.

For more technical information on cement

1. BIS Standard for Cement
2. Cement's role in home construction
3. Grades of concrete
4. Different types of specialty concrete