Civil Engineering - Concrete Technology - Discussion

13.2 Placing.

The concrete shall be deposited as nearly as practicable in its final position to avoid re-handling. The concrete shall be placed and compacted before initial setting of concrete commences and should not be subsequently disturbed.

Methods of placing should be such as to preclude segregation. Care should be taken to avoid displacement of reinforcement or movement of form work. As a general guidance, the maximum permissible free fall of concrete may be taken as 1.5 m.

The free fall height of placing concrete should be 150cm but placing of contete prevented by shrinkage it should not exceed 100cm. So ans1 is correct.

As per IS 456: 2000, it is 1.5m.

But, even 2.1 m shall be adopted without the problem of segregation provided the w/b ratio is maintained properly.

As per clause 13.2 of IS 456: 2000, the maximum permissible free fall of concrete to avoid segregation may be taken as 1.5 m or 150 cm.

To prevent segregation i.e. zero segregation, 1m. The permissible height with some segregation which does not affect strength is 1.5m.

@Shiva Gaire.

But what measures to be adopted while concreting a deep pile? Obviously, its depth is much more than what to do?

150 cm because they ask for maximum value, not minimum. So as per IS 456:2000 it is 1.5 m maximum and 1.0 m minimum height.

Can you say which code is to be preferred? I think it is IS:456-2000.

Am I correct? Because it is the modified code.

As per my knowledge, 100cm is the correct answer if height more than 100cm than segregation start.

Most of exam paper this ans is 1.5 m but in book it is 1.0 m. So what is the right one.