1) 'CHAI-PAANI SYNDROME'.
If the concrete is dropped from over 1 meter height
in a column, it is found that most of the cement mortar gets stuck to the
lateral ties (stirrups). We call this the 'CHAI-PAANI SYNDROME'.The concrete
that reaches the bottom (devoid of mortar) segregates further as it hits the
hardened surface at the bottom.
The result is a weak column.
HOW DO WE AVOID THIS? 'By designing the column
formwork with a WINDOW PANEL'
2) COLUMN FORMWORK WITH A WINDOW PANEL
Generally a window is designed at a height of about
500 mm from the bottom.
Window will help to facilitate concrete placing and
compaction and inspection.
To further avoid the Chai Paani Syndrome, in a
column, no stirrup should be tied for about 500 mm above the 'Bharai level' of
the column.
The gap between the Bharai level' and the stirrup
below it should be at least 40 mm.
3) COLUMN TOPIS
A column with different beam bottom levels should
be filled upto the level of the lowest beam bottom.
Column 'TOPIS' (gap between concreted column top
and to be concreted beam bottom) should be maintained as much minimum as
possible.
More the TOPI height, more difficult is the
concreting of the column with the beams and so more chances of
honeycombing.
4) COLUMN STARTERS
It is found that 100 mm starters are difficult to
vibrate. Well concreted column on a weak starter would be a weak column.
A column starter of 200 mm can best solve this
problem.
BREAKING OF COLUMN IS STRICTLY PROHIBITED.
