CHECKING FOR COLUMN SHUTTERING

Checking of Column Shuttering

Following checks of column shuttering should be carried out before column casting.

Check the size of shuttering for column and it should be as per drawing.
The column shuttering should be strong enough to take the pressure of fresh concrete and remain in position during concreting, particularly when vibrator is applied.
To hold the concrete shuttering firmly in place with proper alignment, concrete starter called “kicker” should be cast before fixing the shuttering and of same concrete mix.
The starter should be hard enough to fix shuttering around it. It should be atleast 4 inch height.
Column formwork box or shuttering for column should be made of plywood sheets with required amount of wooden patties.
Apply water-based shuttering oil on the shutter. It helps to get the good finished surface of the concrete. The shuttering oil enables the easy removal of column formwork after the concrete hardens. It also increases the numbers of shutter repetition, i.e. life of shuttering.
Do not apply oil or grease in place of shuttering oil. It will leave a dark mark on the surface of the concrete. It very difficult to remove oil or grease from the construction joint and in future, the joint becomes weak which may result into the cracks in concrete.
Shuttering should be properly aligned to its verticality and diagonal. It should be checked to ensure the accuracy of dimensions. The column should be acceptably accurate in shape and position with good alignment to other adjacent columns, walls etc. It should be as per predetermined grid specified in drawing.
Plumb the formwork both ways and support it by using adjustable steel props or wooden prop. Ensure the steel props are safely secured to the column formwork and the floor, and that adjustment for pushing and pulling is operational. It is necessary to check the plumb again after providing the supports. Hence check the plumb of column shuttering by using plumb bob.
The propping angle should be 45 °to the floor.
It should be thoroughly supported to props or ties before pouring the concrete so that it does not move horizontally or vertically during concreting.
Sufficient quantity of clamps (shikanjas) should be fixed to prevent bulging of the column during concreting. It should be fixed at a 0.60m (2’0″) interval. Sometimes contractors use binding wire in place of shikanjas, but in large size of columns, they are not effective, and hence not recommended.
Check the size of column as per drawing.
The gap between the joint of shutters should be sealed to prevent any leakage of cement slurry.
Appropriate space to be provided between the inner face of the shutter and reinforcement by fixing cover block as provided in drawing. This is very important to save your column from failure of corrosion of bars.
Make sure that cover block used for casting of column have the same grade as of concrete. They are not broken and properly positioned and should not get disturbed during concreting operations.

Comments

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