Civil Engineering - UPSC Civil Service Exam Questions - Discussion

1. Modulus of rupture is gives the strength of concrete at the breaking point so that it is higher than others.

2. Cube strength is compressive strength which is higher than Split tensile strength. This strength represents the cracking point of the concrete cube, so it will be lesser than the Modulus of rupture.

3. Split tensile Strength was conducted on concrete cylinder so that second option given was wrong. And tensile strength is always lesser than compressive strength of cube.

The answer should be 4, 1, 2 (or) 3.

Modulus of rupture ->Tensile strength under bending is very low.

Split-tensile strength-->Standard tensile strength.

Cube strength for a given concrete mix is 5% to 25% more than cylindrical strength. The variation in percentage corresponds to increase in concrete strength. Hence the correct answer is C) 4, 3, 2, 1.

Civil engineers don't read the question they just matching the answers but they must know that cube strength is compressive strength which always greater than the modulus of (tensile strength) so the correct sequence is 1,2,4,3.

1) fck = cube strength i.e 50 N/mm^2.
2) f'c = 0.8 * fck= 40 N/mm^2.
3) fct = 0.66 * fcr = 0.66*4.94= 3.29 N/mm^2.
4) fcr = 0.7 * Sqrt(fck)= 4.94 N/mm^2.

So, Answer 3, 4, 2, 1.

Split strength = 0.50 - 0.70 modulus of repture.

Cylinder strength = 0.80 cube strength.

So, the sequence is 3 - 4 - 2 - 1.

Cylinder=0.8 x cube strength;

Split tensile strength = 0.66 x modulus of rupture.
So, option A is correct.

Cube strength >Cylindrical strength >Modulus of rupture > split tensile strength.

The answer is asking in decreasing order. Explain please.

Please anyone explain the answer in detail.

I think the Correct answer is 1 2 4 3.