Here's how to procure the right type and quality of cement at your construction site
Introduction to cement
Cement is one of the most widely used materials for construction across the world.
The use of cement in India has grown significantly in recent years, driven by the country's rapid urbanization and economic development.
The Indian cement industry is one of the largest in the world, with around 365 million metric tons of installed capacity as of 2020. A few large players dominate the industry, but there are also many small and medium-sized companies.
The cement production process typically involves mining raw materials such as limestone, clay, and gypsum, crushing and grinding them, and then heating them to a high temperature to form clinker. This clinker is then ground into a fine powder and mixed with gypsum to form cement.
The cement is then packed into bags of 50 kg, transported, and distributed through suppliers. The cement thus follows a robust supply chain. But what about the quality of cement?
Who assures the buyer about the quality? Who specifies the standards for manufacturers to follow and adhere to?
The IS codes.
The IS codes are ready reference guides that standardize parameters for processes, materials, and responsibilities that ensure construction quality across the country.
Introduction to IS codes
The Bureau of Indian Standards publishes the Indian Standard codes for the harmonious development of the activities of standardization, marking, and quality certification of goods. These codes are prepared after extensive research done across the country by reputed construction companies and organizations. The IS codes are freely available in public resources and you can download them from the internet.
The same standards have covered the specification for various types of cement. Let's have an overview of a few of the important IS codes to know how to procure and maintain cement quality at a construction site.
IS codes on the specification for types of cement
1. IS 455: 1989
IS 455: 1989 is about the specification of Portland Slag Cement. The code covers the manufacture and physical and chemical requirements for Portland slag cement.
Portland cement is a mixture of clinker and granulated slag blended with gypsum. The addition of additives gives the cement its unique properties, making it perfect for use in construction projects.
The code briefs about the limits of chemical constituents in clause 5. It then talks about the physical requirements like fineness, soundness, setting time, and compressive strength, both chemical and physical requirements are to be checked by the purchaser to ensure that the manufacturer has fulfilled them.
Clauses 8 and 9 cover the manufacturer's responsibilities like providing a certificate along with the delivery of cement, and the packaging standard to be maintained while delivery.
The code finally speaks about sampling, testing, and rejection terms. These sections cover the roles and responsibilities of both the supplier and the purchaser.
Annexure B has a tolerance requirement for the mass of cement packed in bags. These limits help ensure the procured cement is of the right quantity.
Portland slag cement is usually used in seawater construction projects. It is also used as an alternative to Ordinary Portland Cement.
Alternatively, if the construction is to be carried out for hydraulic structures, marine works, mass concreting, dykes, retaining walls, foundations, and sewage pipes, then Portland Pozzolana cement is best suited. Let's look in brief at Portland Pozzolana Cement and the related IS code.
2. IS 1489: 1991
IS 148 is about specification for Portland Pozzolana Cement. As per the definition, Pozzolana is an essentially silicious material which while in itself possessing little or no cementitious properties will, in finely divided form and in the presence of water, react with calcium hydroxide at ambient temperature to form compounds possessing cementitious properties.
Pozzolanas also include natural volcanic material having pozzolanic properties. Other natural and artificial materials, such as diatomaceous earth, calcined clay, and fly ash, are also generally counted as pozzolana.
This code is divided into two parts:
- Part 1 covers fly ash pozzolana
- Part 2 covers calcinated clay based pozzolana.
Fly ash, as the code suggests, shall conform to requirements as mentioned in the IS 3812: 1981. The code also suggests limiting the use of fly ash. It says, "The fly ash constituent must not be less than 10 percent and not more than 25 percent by mass of Portland-pozzolana cement.
Part 2 of the code mentions, "The Portland-pozzolana cement must have a pozzolanic content of no less than 10% and no more than 25%."
The structure of this code is similar to that of IS 455.
3. IS 3466: 1988
This IS code is about specifications for masonry cement.
Masonry cement is mainly used for use in masonry mortars for brick, stone, and concrete block masonry, and for rendering and plastering work.
Masonry cement is obtained by intimately grinding a mixture of Portland cement clinker and gypsum with pozzolanic or inert materials, and air-entraining plasticizer, generally to a fineness greater than that of ordinary Portland cement.
The IS 3466 has a structure similar to that of IS 455.
4. IS 650:1991
IS 650 is about the specification for standard sand for testing of cement. Standard sand is also known as Ennore sand, it is named as it is obtained from the place Ennore, Tamil Nadu.
Ennore sand is used to access the quality of cement, lime, and other mineral admixtures that can be used in construction industries.
The IS 650: 1991 suggests that the standard sand be obtained from Ennore Tamil Nadu, or particle size greater than 1 mm of the Standard sand may also be obtained from Mudaliarkuppam, Tamil Nadu.
The code mentions the physical characteristics, chemical requirements, delivery, and marking for the standard sand. You can also look out for these parameters if you are either the supplier or buyer to assure you buy up the right quality material matching your needs.
Similar codes that cover the specification of cement include:
5. I.S. 8112: 1989 - Specification for 43-grade Ordinary Portland Cement
6. I.S. 12269: 1987 - Specification for 53-grade Ordinary Portland Cement
7. IS. 269: 2015 - Specification for 33-grade Cement
These codes are also structured in a similar fashion.
Application of IS codes on specifications for cement
The IS codes can help ensure you buy the right quality cement for your construction project.
The IS codes have eased the standardization work. You can simply refer to any relevant code to get an idea about the specific part of construction practice.
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