To hold the concrete shuttering firmly in place and for proper alignment a concrete pad called starter is cast before fixing the shuttering. The thickness is about 45 mm to 60 mm and dimensions are precisely the same as the dimensions of proposed column. The starter should be cured for a day or 2 so that it is hard enough to fix the shuttering around it.
Column box or shuttering for columns is made of plywood sheets or steel sheets fabricated with adequate stiffeners.
A thin films of oil or grease should be applied to inner surface of the shuttering to enable easy removal of the column after the concrete hardens.
Shuttering should be properly aligned to its verticality and diagonals to be checked to ensure accuracy in dimensions.
Formwork has to be thoroughly supported with props size before pouring the concrete so that it does not moves horizontally or vertically during concreting.
The gaps near the shuttered joints should be sealed with plaster or a piece of wood to prevent any leakage of slurry.
Appropriate space is to be provided in the inner face of the shutter and reinforcement by fixing cover blocks of about 40mm.
It is preferable to remove shutters after 24 hrs. of casting and if they need to be removed earlier, it should not be removed within sixteen hours.
The removal of shutters has to be done gently without jerks so that edges of columns are not damaged.
Care should be taken regarding fixing and supports of column shuttering to prevent it from movement during concreting.
Diagonals of the shuttering to be checked to ensure dimensional accuracy.
