Part – 3 : BIS Specifications..

For concrete Technology the most important IS code is IS 456:2000.

*Indian Standard*

### PLAIN AND REINFORCED CONCRETE – CODE OF PRACTICE

No doubt, each and every specifications in IS code is important but some of them are not so important for site use or exam point of view. so we are trying to put IS code in an efficient way.

so, here are some of the important specifications for concrete :

**Characteristic strength**– Strength of concrete below which not more than 5% of test results are expected to fall. Normally the process of gaining strength is beyond 28 days but the design should be based on 28 days characteristic strength.flexural strength is calculated using compressive strength by following formula.**Tensile Strength –****Modulus of elasticity –**It can be assumed as following**Shrinkage**– The shrinkage of concrete is significantly influenced by the total amount of water present while mixing and slightly influenced by cement content. the approximate value to total shrinkage strain for design may be taken as 0.0003.**Creep –**The creep coefficient, used to calculate creep, depends upon age of concrete when load is applied on it. Creep coefficient is the ratio of**Ultimate creep strain**to**Elastic strain**at the age of loading. When experimental data is not given, table provided by BIS can be used to calculate creep coefficient.**Workability –**Its ease of work with concrete. Five degrees of workability according to BIS tabulated as follows**Durability –**Durability of concrete is influenced by following factors –- The surround climate condition.
- The cover to embedded steel.
- The type and quality of constituent materials.
- The cement content and water-cement ratio of the concrete.
- Workmanship for full compaction and efficient curing.
- Shape and size of the member.

**Exposure Conditions –**There are five environmental exposure conditions**Concrete Mix Proportioning –**- This is calculation of exact quantities of constituent materials to achieve desired degree of workability of fresh concrete and strength, surface finish of hardened concrete. There are two methods of concrete mix –
- Design Mix Concrete.
- Nominal Mix Concrete.

- Design mix is preferred over nominal mix in concrete of grade 20 and above. and Nominal mix is preferred for concrete of grade 20 and below it.
- Design mix proportions must be by weight while nominal can be done either by volume or weight but weight is preferable.

- This is calculation of exact quantities of constituent materials to achieve desired degree of workability of fresh concrete and strength, surface finish of hardened concrete. There are two methods of concrete mix –

We will be back soon with more specifications on production of concrete, compaction, formwork, curing, placing and transportation of concrete, etc

### Thank You!

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