Steps for Construction of Formwork
Formwork in construction means the application of support structures and moulds to form structures out of concrete that is poured into the moulds. Formwork is built up with moulds which comprise of steel, wood, aluminium and/or prefabricated forms.
The process for eliminating the formwork is called as stripping. Stripped formwork can be reprocessed. Recyclable forms are defined as panel forms and non-usable are defined as stationary forms.
A superior formwork should have the following characteristics :-
- Good strength to resist various types of dead and live loads.
- Firmly built up effectively propped and braced both horizontally and vertically in order to keep its proper shape.
- The joints in the formwork should have been tight to get rid of leakage of cement grout.
- Construction of formwork should allow elimination of different parts in required sequences devoid of any damage to the concrete.
- The materials provided in the formwork should be cost-effective, easily accessible and suitable for reprocessing.
- The formwork should be arranged perfectly to the required line and levels should contain plane surface.
- It should be as light as possible.
- The material of the formwork should not wrap or become deformed when uncovered to the components.
- The formwork should be supported on rigid base.
- The plan of the structure should involve least number of variations in the size of rooms, floor area etc. in order to facilitate reprocessing of the formwork frequently.
- The design should be proper to apply slender sections only in a most reasonable method.
- Minimum sawing and cutting of wooden pieces should be built up to facilitate reprocessing of the material a significant period of time. The quantity of surface finish is based on the quality of the formwork.
Forwork for column
It comprises of the following :-
- Side & End Planks
- Nut and Bolts
Two end & two side planks are attached with the yokes and bolts.
Construction sequence for a column
Before placing column formwork, verify that steel for the column is checked and cleared for casting.
- Place formwork for the column from prearranged grids.
- Plumb formwork both ways and safely support with modifiable steel props.
- The propping angle should have been 45 degree to the floor.
- Make sure that the steel props are securely attached to the column formwork and the floor. Modification for pushing & pulling is going on.
- Arrange the placements of column clamps from a storey rod.
- Move the column damp positions from the storey rod onto column formwork.
- Apply nails to provide support to the arms of column clamps at the time of wedging.
- Place and wedge the bottom, middle and top clamps sets.
- Examine the formwork at the top for square.
- Place and wedge the rest of the column clamps.
- Plumb the column with a plump bob that is hanging from a gauge block.
When, all the column formworks are safely propped, final examination should be done for plumb & column alignment prior and promptly after the concrete is poured and vibrated.