What will happen if the concrete will not be vibrated in columns?
This is what happens when you do not properly compact concrete (especially in columns and shear walls)
The image represents a Honeycombed Shear Wall.
The reason behind this is the improper compaction. The height of column is minimum 3 m (considering single storey) and they are usually cast from floor to roof level as a single member in one stage (without any intermediate joints)
.So the concrete has to pass all the reinforcements and form a homogeneous mixture to prevent honeycomb. So we compact the concrete by giving external energy to the mixture to eliminate the air voids.
Honeycomb also occurs due to bleeding of concrete from the sides and bottom of the formwork. Excess compaction also causes bleeding. So the compaction must be done neither too short (duration) nor too long.