IS 456 - 2000 all updates and changes every civil engineer should know

 

IS 456 - 2000 all updates and changes every civil engineer should know

 

The Civil Engineering industry's foundation is based on all norms and standards. Civil engineers must know all codes and standards that will be complied with in their field of work. The code and compliances are made to ensure the safety and durability of structures.

Each code holds its importance, similarly IS 456 - 2000 describes the practice for general structural use of plain and reinforced concrete. In this blog, we will explore all updates and changes that every civil engineer should know about IS 456 - 2000.

What is IS 456 and IS 456 - 2000?

IS 456: The IS 456 was published by the Bureau of Indian Standards (BIS) and describes the practice of general use of plain and reinforced concrete in India for construction projects. It is a widely used standard. For the design and construction of reinforced concrete structures original code IS 456:1978 was introduced.

IS 456 – 2000: The IS 456 - 2000 is a revised version of the standard released in July 2000 with important amendments and updates to meet the changing demands and developments in the field of civil engineering.

Certainly IS 456 – 2000 has seen a lot of changes over time, issued in years Amendment 1 June 2001, Amendment 2 September 2005, Amendment 3 August 2007, Amendment 4 May 2013, and Amendment 5 July 2019 due to certain developments in the industry.

As a civil engineer, you should know how and what changes have been made over time.

Understanding Key Clauses in IS 456:2000 (Before and After Amendments)

There are certain major amendments in important clauses over time, So let's check all amendments and what were the clauses originally and what were the changes made in those:

Table No. 2, Page 16 (Grades of Concrete):

The structural requirements and expected loads on the concrete element determine the choice of concrete grade therefore table 2 describes different grades of concrete along with their compressive strength.

Before Amendment: The 3 grade groups were Ordinary Concrete, Standard Concrete, and High Concrete Strength.

Where grade designations were:

Ordinary Concrete: M10, M15 and M20

Standard Concrete: M25, M30, M35, M40, M45, M50, M55

High Strength Concrete: M60, M65, M70, M75, M80

After Amendment: The change in cement grade has been introduced where, Previously M60 grade was included under High Strength concrete, but now it falls under standard concrete.

Whereas, New grades M85, M90, M95, and M100 under High Strength Concrete have been added. Before Updates: The 3 grade groups were Ordinary Concrete, Standard Concrete, and High Concrete Strength.

Revised grades are as follows:

Ordinary Concrete: M10, M15 and M20

Standard Concrete: M25, M30, M35, M40, M45, M50, M55, M60

High Strength Concrete: M65, M70, M75, M80, M85, M90, M95, and M100

In summary, The revised version of the table now provides more accurate guidelines for the selection of the grade of concrete to ensure better structural strength.

Clause 11.3.1, Page No. 25 (Type of Formwork):

 

The clause describes the criteria of formwork, which is essentially required to shape and support freshly poured concrete until it sets.

Before Amendment: The previous version of the specifications possibly were outdated or less comprehensive.

After Amendment: The table of clause 11.3.1 has been revised where the Minimum Period Before Striking Formwork has been divided into 2 part: For Concrete Made Using OPC and other For Concrete Made Using Other than OPC or Using Mineral Admixtures like Fly Ash and Slag.

Revised line in clause 11.3.1 last sentence: For lower temperature, the stripping time recommended above may be suitably modified and new clause 11.3.1.1 has been added.

Clause 11.3.1 has been revised as: While the above criteria of strength shall be the guiding factor for removal of formwork, in normal circumstances where ambient temperature does not fall below 15*C, following striking period may be deem to satisfy the guideline given in 11.3.

In summary, The updated version of the clause promotes standard practices to reduce the possible risk related to formwork due to construction.

Clause 5.1, Page No. 13 (Material - Cement):

After Amendment: The changes include the use of Ordinary Portland Cement where clauses 5.1(b) and (c) have been deleted on page 13. Whereas Clause 5.1(a) has been revised as " Ordinary Portland Cement conforming to IS 269".

Before Amendment: The guidelines for the use of Ordinary Portland cement where 5.1(b) Grade 43 conforming to IS 8112 and 5.1(c) Grade 53 conforming to IS 12269 were still in use and 5.1(a) was mentioned as "33 Grade ordinary Portland cement conforming to IS 269". In summary, The updated section focuses on the importance of using better-quality Ordinary Portland Cement cement for strong and durable concrete structures, Also the 33 Grade for Ordinary Portland Cement was mentioned previously.

Clause 5.3 (Aggregates):

Clause 5.3 describes the requirements for aggregates used in concrete mixtures

Before Amendment: Aggregates shall comply with the requirements of IS 383. As far as possible preference shall be given to natural aggregates.

After Amendment: Aggregates shall comply with the requirements of IS 383.

In summary, the clause focuses on enhancing concrete strength and consistency by defining accurate aggregate standards.

Clause 5.3.4:

The clause refers to certain criteria and tests for aggregates to ensure that aggregates are suitable for use in concrete production.

Before Amendment: Coarse and fine aggregate shall be batched separately. All- in-aggregate may be used only where specifically permitted by the engineer-in-charge.

After Amendment: Coarse and fine aggregate shall be batched separately.

In summary, the updated version of the clause focuses on the quality assessment of aggregates for making high-quality concrete mixes

Clause 5.4 (Water):

Clause 5.4 specifies the quality of water to be used for concrete mixtures.

Before Amendment: Water used for mixing and curing shall be clean and free from injurious amounts of oils, acids, alkalis, salts, sugar, organic materials, or other substances that may be deleterious to concrete or steel.

After Amendment: Water, natural or treated, used for mixing and curing shall be clean and free from injurious amounts of oils, acids, alkalis, salts, sugar, organic materials, or other substances that may be deleterious to concrete or steel.

 

In summary, To prevent the potential negative impact on material quality, clause 5.4 focuses on using clean water while making concrete mixtures.

Clause 5.4.3 (Seawater):

The clause focuses on the use of seawater in concrete, considering its properties and potential impact on concrete efficiency.

Before Amendment: Mixing or curing concrete with seawater is not recommended because of the presence of harmful salts in seawater. Under unavoidable circumstances, seawater may be used for mixing or curing in plain concrete with no embedded steel after having given due consideration to possible disadvantages and precautions including the use of an appropriate cement system.

After Amendment: Seawater shall not be used for mixing or curing concrete because of the presence of harmful salts. Under unavoidable circumstances, seawater may be used for mixing or curing in plain concrete with no embedded steel after having given due consideration to possible disadvantages and precautions including the use of an appropriate cement system., In Summary, The updated clause focuses on the careful and safe use of seawater in concrete in certain circumstances, Considering its salt component and its possible impact on the durability of content.

Conclusion:

The IS 456 - 2000 is a foundation that gives detailed requirements and guidelines to ensure safe, durable, and strong structures. The IS codes indeed are provided by BIS to ensure safe and sound construction while maintaining its quality considering a quickly evolving environment.

By adopting the updated IS 456 - 200 in construction projects, civil engineers can provide high-quality construction and excellence.

Note: It is difficult to point out all the changes in the blog, The blog is made to understand the major changes.

Therefore refer to the document attached and compare before amendment in 456:2000 , after amendment  and after amendment table no. 2 learn all the changes and revisions made in IS 456:2000.