Standard Deviation in concrete

Standard deviation is a measure of difference of test results from its average. It can be said that it is a measure of deviation from the Quality of concrete from batching of concrete to pouring point where sample cubes are prepared. A standard value is added in charterstic strength of concrete multiplying 1.65 to find out target mean strength while design mix.

30 samples (consisting 3 cubes each) are prepared to establish standard deviation, if data is not avilable values from IS 456 table 8 can be taken as follows : M-10 and M-15: 3.5, For M-20 and M-25 : 4 N/mm2, Above than M -25 : 5.0 N/mm2

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