What is the compressive strength of concrete block in N/mm2 and Kg/cm2. Compressive strength of concrete block as IS code: As per IS : 2185 (Part I) – 1979, the min. average (of 8 samples) compressive strength is 5 MPa, with individual value not lesser than 4 MPa and As per IS : 2185 (Part II) – 1983, (Light Wt.) the min. average (of 8 samples) compressive strength is .