Indian Standard – BIS 456:2000 (PLAIN AND REINFORCED CONCRETE – CODE OF PRACTICE)( Fourth Revision)
The Bureau of Indian Standards adopted This Indian Standard (Fourth Revision) after the draft finalized. By the Cement and Concrete Sectional Committee had been approved by the civil engineering Division Council.
This standard was first published in 1953 under the title ‘Code of practice for plain and reinforced concrete for general building construction’ and subsequently revised in 1957.
The code was further changed in 1964 and published under the modified title ‘Code of practice for plain and reinforced concrete,’ thus enlarging the scope of use of this code to structures other than general building construction also.
The third revision was published in 1978, and it included the limit state approach to design. This is the fourth revision of the standard.
This revision was taken up with a view to keeping abreast of the rapid development in the field of concrete technology and bringing further modifications/improvements in the light of experience gained while using the earlier version of the standard.
This revision incorporates several significant changes. Themajorthrustin the review is on the following
- a) In recent years. The Durability of concrete structures has become the cause of concern for all concrete
technologists.This has led to the need to codify the durability requirements world over. In this revision
of the code.
In order to introduce in-built protection from factors affecting a structure, an earlier clause on
durability has been elaborated, and a detailed clause covering different aspects of the design of the durable
construction has been incorporated.
- b) Sampling and acceptance criteria concrete have been revised. With this revision acceptance criteria
has been simplified in line with the provisions given in BS 5328 (P8l1 4):1990 ‘Concrete: Part 4
Specification for the procedures to be used in sampling, testing, and assessing compliance of concrete’.
Some of the significant changes incorporated in Section 2 are as follows:
- a) All three grades of ordinary Portland cement, namely 33 grade, 43 grade, and 53 grade, and sulfate
resisting Portland cement have been included in the list of types of cement used (in addition to other
kinds of cement).
- b) The permissible limits for solids in water have been modified, keeping in view the durability requirements.
- c) The clause on admixtures has been amended in view of the availability of new types of admixtures, including superplasticizers.
- d) In Table2 ‘Grades of Concrete’, grades higher than 40 have been included.
- e) It has been recommended that the minimum grade of concrete shall be not less than M 20 in reinforced
concrete work (see also6.1.3).
- f) The formula for estimation of modulus of elasticity of concrete has been revised.
- g) In the absence of proper correlation between compacting factor, vee-bee time and slump, workability
has now been specified only in terms of the slump in line with the provisions in BS 5328(Parts 1 to 4).
- h) The durability clause has been enlarged to include detailed guidance concerning the factors affecting durability.
The table on ‘Environmental Exposure Conditions’ has been modified to include ‘very severe’ and
‘extreme’ exposure conditions. This clause also covers requirements for shape and size of the member,
depth of concrete cover, concrete quality, provision against exposure to aggressive chemical and sulfate
attack, minimum cement requirement and maximum water-cement ratio, limits of chloride content. Alkali-silica reaction, and importance of compaction, finishing, and curing.
- j) A clause on-‘Quality Assurance Measures’ have been incorporated to give due emphasis to good practices
- k) Proper limits have been introduced on the accuracy of measuring equipment to ensure accurate batching
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