Civil Engineering - Concrete Technology - Discussion

It is 150 kg/cm^2 only. Option B is correct. Don't confuse between permissible and ultimate strength.

If we design the mix for M150 grade means permissible will be 150kg/cm^2 only. Sometimes during testing due to some variations strength decreases for ex.130 or 135kg/cm^2 or 200kg/cm^2 even if we designed for M150 grade concrete. But we designed for M150 means we must conclude the answer to be 150kg/cm^2 irrespective of what ever we obtained.

In SCC sometimes permissible strength varies due to trail and error Mix design methods,but here they didn't mention anything as SCC(Self Compacting Concrete)
Finally, option B is correct.

Hope this will clear the confusion.

It's 150 because M150 means M denotes design mix of concrete and 150 denotes the permissible comprehensive strength of concrete after 28 days of 150mm cube.

Like GRADE OF CONCRETE- CSO CONCRETE
M15 15
M20 20 Etc

Here, permissible strength is required to be determine fck 150 is already given. So, permissible strength= fck/partial safety factor.

150/1.5 = 100 kg/sq.cm.

fck = characteristic compressive strength of concrete at 28 days after curing.

Answer should be 37.5Kg/cm2 for direct compression and 40Kg/cm2 for bending compression, 150 is Characteristic strength not permissible.

For M150 the compressive is 150 kg/cm2 but this is ultimate compressive strength not permissible compressive strength.

100 kg/cm2 is the right answer because we allow it after failure in compressive standard unit.

I know that compressive strength of M150 is 150kg/cm2, but it is 200kg/cm2 how?

I know that compressive strength of M150 is 150kg/cm2, but it is 200kg/cm2 how?

But permissible compressive strength must be law. How it can be more?

What the difference between permissible and characteristics strength?