Civil Engineering - Concrete Technology - Discussion

In thin and heavily reinforced structures needle vibratore cannot be used hence workable concrete is required.

I think option C is correct : When a section is narrow, complicated, several narrow corners, inaccessible parts; a highly workable concrete is desirable to obtain full compaction through a reasonable amount of effort. When the section is crowded with steel reinforcement and spacing of bars is relatively small, compaction can be difficult and hence highly workable concrete is recommended in such cases. If there are no limitations of the critical section or heavy reinforcement, we can get a wide range of workability for concrete casting.

I think it should be "Thick Reinforcement & Heavily Reinforced".

Eg. 12 @ 25mm rod in a Column.

The given answer i.e. Option (D) is indeed the correct option.