Standard deviation of concrete – sample calculation

How to calculate standard deviation of concrete

Standard deviation of concrete is the root mean square deviation of all results. Standard deviation is generally denoted by s OR σ. Mathematical formula to calculate standard deviation is as per following

 

standard-deviation

Sample calculation of standard deviation of concrete cube results

No of tests Test Result x Average Deviation Square of deviation
1 44 40.05 3.95 15.60
2 40 -0.05 0.00
3 39 -1.05 1.10
4 42 1.95 3.80
5 38 -2.05 4.20
6 35 -5.05 25.50
7 45 4.95 24.50
8 41 0.95 0.90
9 36 -4.05 16.40
10 38 -2.05 4.20
11 42 1.95 3.80
12 40 -0.05 0.00
13 39 -1.05 1.10
14 44 3.95 15.60
15 38 -2.05 4.20
16 44 3.95 15.60
17 42 1.95 3.80
18 36 -4.05 16.40
19 40 -0.05 0.00
20 38 -2.05 4.20
Total 801 160.95

Standard Deviation = SqRoot ( 160.95 / (20-1)) = 2.91

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