Indian concrete strength (M) conversion to ACI (f'c)

[SantoZoo]

Dear All,

Please your kindly help.
I want to know about Indian concrete strength which indicated by M.
But the ACI use f'c (MPa, from cylinder concrete).

1. Is there any formula to convert from M to f'c?
2. is it M stated in kg/cm2 or MPa? and is it obtained from cube concrete?

Please your kindly explanation.
Thank you.


Best Regards
Santo

 

[slickdeals]

Indian concrete strengths are based on testing cubes (fck), while the ACI f'c is based on cylinder strength. A rough rule of thumb to convert cube to cylinder is fcylinder = 0.83 * fcube

 

[BigH]

I usually use 0.8, not 0.83. There are some studies that the actual ratio varies according to the strength of the concrete.

 

[SantoZoo]

Thanks slickdeals and BigH..

So, basically M is based on cube testing.

For example M200, (I think it's still in kg/cm2, right? )
I can convert it 200x0.083 = 16.6 MPa
Is it correct?

Please your kindly confirmation.
Thank you.


Best Regards
Santo

 

[slickdeals]

NO, it is in MPa. M60 = 60 MPa cube strength. An equivalent cylinder strength would be 0.8*145*60 ~ 7000 psi.

 

[bkal]

Table 3.1 of BS EN 1992-1-1:2004 gives both strengths, i.e. f.ck (cylinder) and f.ck,cube.