The Bureau of Indian Standards has graded the ordinary Portland cement into three grades, namely, 33 grade, 43 grade and 53 grade. The compressive strength of these cement at 28 days is at least 33 MPa, 43 MPa and 53 MPa. respectively. Separate specifications have been brought out for each grade of cement to deal with their physical and chemical properties. In addition, the B.I.S. has further classified the cement into seven categories on the basis of 28-days compressive strength as follows:
A: 32.5 – 37.5 MPa
B: 37.5 – 42.5 MPa
C: 42.5 47.5 MPa
D 47.5 – 52.5 MPa
E: 52.5 – 57.5 MPa
F: 57.5-62.5 MPa
G: 62.5 – 67.5 MPa
