RCC Column Construction Methods consist of various steps and procedures to follow in the construction of columns at the site.
RCC Column Construction Methods
Layouts
Reinforcement work
Formwork
Pouring of concrete
1. Layout
Layouts proceed by surveying instrument. After marking the grid lines, the location of columns Identifies and marks.
2. Reinforcement work
Checklist for Column reinforcement works on site:
Check the numbers and diameter of vertical bars
The spacing between vertical bars
Development length which depends on the diameter of the bar
Lapping in alternate bars to come at the same height and not coming inside beam or slab.
Lapping l/3 or 2l/3 of column
The spacing between stirrups
The hook bends properly at right angles
Check the stirrups corner
3. Formwork
Columns carry a load of the structure so it is critical. It is important to align column for verticality so that load transmits properly. The column shuttering should strong enough to take the pressure of fresh concrete and remain in position during concreting.
Guidelines on column shuttering
Holding the concrete shuttering firmly in place and for proper alignment, a concrete pad is cast before fixing the shuttering. The starter cures for a day or two 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 fabricators with adequate stiffeners.
Thin films of oil/grease applies to the inner surface of shuttering to easily remove from a column. After the concrete hardens.
Shuttering is properly aligns with its verticality and diagonals are checks to ensure accuracy in dimensions.
Formwork thoroughly supports with props size before pouring the concrete. So that it does not move horizontally or vertically during concreting.
Gaps in shuttering joints to seal with plaster or a piece of wood to prevent leakage an of a slurry.
Appropriate space to provide in the inner face of the shutter and reinforcement by fixing cover blocks.
It is preferable to remove shutters after 24 hrs of casting. If need to remove earlier, it should not remove within sixteen hours.
The removal of shutters is handling gently without jerks so that edges of columns will safe without damages.
supports of column shuttering to prevent from moving during concreting.
Diagonals of the shuttering to check to ensure dimensional accuracy.
4. Concreting of RCC Column
Concreting of an RCC column is by two methods
Manually
With the help of machine or pump
Points to follow during and after concreting:
For less quantity machine mix concrete adopts and for larger quantity, ready-mix concrete (RMC) orders.
Approval of placing concrete whether by pump or manually from the client.
Concrete pours up to slab bottom; the remaining column gets concrete during pouring of slab & beam.
Mechanical vibrator to compulsorily use in the column but excess vibration cause segregation. Each layer is to compact thoroughly.
Target slump to be 160 mm.
The height of pouring concrete should not exceed 1.5 m.
Avoid construction joint in the column.
check proper cover.
The temperature should be below 30 degrees while pouring concrete.
After the pouring and vibrating, the horizontality and verticality of the column to check.