The OPC was classified into three grades, namely 33 grade,
43 grade and53 grade depending upon the strength of the
cement at 28 days when tested as per IS 4031-1988. If the 28
days strength is not less than 33N/mm2, it is called 33
grade cement, if the strength is not less than 43N/mm2, it
is called 43 grade cement, and if the strength is not less
then 53 N/mm2, it is called 53 grade cement.
can any body tell me that we stdy different grades of
concrete $ their strength . as we knot the strength of
conrete that this grade or ratio of concrete has this much
strength ? even that we go for labortory test what is
reason behind that?