Testing High Strength Prestressed Concrete Cubes

High strength prestressed concrete cube tests guidelines are guidelines prescribed in the Indian standard code IS: 1343-1980 with respect to quality of materials used in prestressed concrete.

The minimum 28 day compressive strength of concrete cubes of 15 cm size, prescribed in the Indian standard code IS: 1343-1980, is 40 N/mm2 for pre-tensioned concrete and 30 N/mm2 for post-tensioned concrete. The characteristic strength of concrete is defined as the strength of the concrete below which not more than 5 percent results are expected to fall.

The code specifies standard guidelines regarding sampling and strength test of concrete to be use in prestressed concrete. .These requirements are given in the table below.


Grade of Concrete Assumed standard deviation in N/mm2 Compressive strength of 15cm cubes (minimum at 7 days)


Modulus of rupture by beam test (Minimum)
M30 6.0 20.0 2.1 3.0
M35 6.3 23.5 2.3 3.2
M40 6.6 27.0 2.5 3.4
M45 7.0 30.0 2.7 3.6
M50 7.4 33.5 2.9 3.8
M55 7.7 37.0 3.1 4.0
M60 7.8 40 3.3 4.2

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