Civil Engineering - GATE Exam Questions - Discussion

34. 

The cylinder strength of the concrete is less than the cube strength because of

[A]. the difference in the shape of the cross section of the specimens
[B]. the difference in the slendeness ratio of the specimens
[C]. the friction between the concrete specimens and the steel plate of the testing machine
[D]. the cubes are tested without capping but the cylinders are tested with capping

Answer: Option B

Explanation:

No answer description available for this question.

Sneha Wankhede said: (Aug 31, 2016)  
There is no slenderness ratio comparison between the specimen.

So the answer is either C or D.

Snehal Wankhede said: (Aug 31, 2016)  
Option D.

The cylinder is tested with capping (used in UN) which generates compaction only on the effective length of the cylinder (out of 300 mm) whereas in cube testing (used in India) tested without capping (which is not a correct procedure that is why we use this expression cyl strength = 0.8x cube strength).

Snehal Wankhede said: (Aug 31, 2016)  
OPTION C governs the true reason.

Although cube strength doesn't determined by capping but the steel plates of machines provide lateral restrained due to friction between steel plates and cube. Lateral restrain increases strength of cubes in that direction.

Giridhar said: (Dec 30, 2016)  
Can, I know the correct answer?

Rahul said: (Jan 10, 2017)  
I think C is right answer.

Pooja Sonar said: (Jan 24, 2017)  
@Rahul.

How C is a correct answer? Explain.

Suraj said: (Feb 12, 2017)  
B is Correct.

Slenderness Ratio is different in both specimens.

Azhar said: (Mar 22, 2017)  
Answer is C. Platten effect is the main reason.

Harish said: (Nov 2, 2017)  
Option C is correct.

There is no friction in the middle portion for cylindrical cube.

Roy said: (Nov 27, 2017)  
D is the right option.

Prathik said: (Feb 4, 2018)  
C is the right answer. Area of contact of cube is more than that of cylinder for given volume.

Swapnil said: (Feb 6, 2018)  
The right answer is C.

Bijan said: (Sep 6, 2018)  
Concrete cubes under axial compression fail in lateral tension due to poisson's effect. If the contact surface between the concrete cube and plate of the testing machine is rough, inclined cracks form otherwise almost vertical cracks form if surface between cube and plate is smooth. So option C is correct.

Pawan Pinto said: (Aug 23, 2019)  
Option B is correct. When Effective length to least lateral dimension is considered here value of lamda is more for cylindrical section and hence more chance of failure.

Lakshya Yadav said: (Sep 12, 2019)  
The correct answer is A, friction is present in both the cases but in-cylinder its impact is negligible as compared to cube because of its larger cross-section area i.e. shape is different of cross-section.

Mohit said: (Dec 5, 2019)  
The answer is C middle portion of the cylinder has a negligible effect of friction.

Gopala Krishna said: (Feb 3, 2020)  
Option 'C' is correct.

Niladri Roy said: (Feb 29, 2020)  
The correct option is C.

The middle portion of the cylinder has the negligible effect of friction. Cube has a uniform effect throughout.

T R Garg said: (Sep 10, 2020)  
C is the correct answer in this question because the restraining effect due to friction.

Sagar said: (Sep 14, 2020)  
According to me here we can apply the concept of Section of moduls (Z). Z increase than strength increase &in cylinder z is less compare to cube.

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