**What is fck in concrete mix design**

### ● **what is fck in concrete**

● **introduction** :- in this topic we know about what is fck in concrete mix design and what is full form of fck in concrete. There is a need of know about value of fck for every civil engineer aur architect designer for building construction work. When we calculate concrete and estimate value and design for theire project we need fck value of concrete.

● **fck stand for**

Full form of fck is characteristics of compressive strength of grade of concrete and it is is measured in in Newton per mm square or mega pascal. We have different grade of concrete like **M20, m25, M30 ,m35 ,m40 ,m45 ,m50** and so more—-its meaning of following for example if we have M20 grade of concrete it means it has characteristics of compressive strength is about 20 N/mm2 and for **M 25 grade of concrete compressive strength is 25 N/mm2**

● **compressive testing machine (CTM)**

The characteristics of compressive strength of cube concrete can be tested with the help of compressive testing machine (CTM)in the laboratory. In the test process of comprehensive strength of concrete cube suppose we have 100 concrete cube of M20 grade of concrete. All the concrete cube tested with compressive testing machine than following result is obtained

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**1) calculate self load of column**

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**4) calculate dead load of brick wall per metre**

**5) ultimate load carrying capacity of column**

**Test ,Rules and result**

1) if 5% and less of concrete cube of M20 grade of concrete fail to withstand with compression pressure of 20N/mm2 in CTM machine in laboratory and 95% and more of concrete cube of M20 grade of concrete with stand with compression pressure of 20N/mm2 in CTM machine than it is called as successful of your test of concrete and their characteristics of comprehensive strength of M 20 grade of concrete is about 20 N/mm2

2) if more than 5% of concrete cube of M20 grade of concrete fail to withstand with compression pressure of 20N/mm2 in CTM machine in laboratory and less than 95% concrete cube of M20 grade of concrete with stand with compression pressure of 20N/mm2 in CTM machine than it is called as fail of your test of concrete and their characteristics of comprehensive strength of M 20 grade of concrete is less than 20 N/mm2.