Determine about the post-tensioned concrete

The transfer stage may take place after a long time from the casting of concrete, in the case of post-tensioned,members, enabling the concrete to achieve a very high strength. This is the reasoA that IS :1343-1980 specifies a larger minimum concrete grade of M 40 (a concrete mix whose 15 cm cubes achieve a compressive strength of 40 N/mm2 after 28 days of curing in water under specified conditions of temperature) compared to M 30 grade of concrete in the case of post-tensioned concrete members.