Correct Answer - Option 4 :
\(2 \over3\)
Strength of concrete:
It is designated in terms of numbers preceded by the letter ‘M’ where M refers to the ‘Mix’ and number represents the characteristic strength.
Tensile strength of concrete = 10% of compressive strength
Bending strength of concrete = 15% of compressive strength
Shear strength of concrete = 20% of compressive strength
|
Days
|
Strength of concrete
|
|
3
|
\(\frac{1}{2}\)× Fck
|
|
7
|
\(\frac{2}{3}\)× Fck
|
|
14
|
0.9 Fck
|
|
28
|
Fck
|
So, ratio between the strength of concrete at 7 days to 28 days is \(\frac{2}{3}\)
