This article brings you details of the form work in a simple language.
Form work is the temporary arrangement for giving support to the concrete till it gains the strength.
All horizontal faces are supported by centering whereas the vertical faces get supported by shuttering.
Entire arrangement is such that it is temporary and is in position only till the concrete attains
Therefore it is essential that the erection and dismantling of formwork must be easy and safe.
Further, if the strike-off is not done smoothly, it may damage the edges of concrete due to jerks & twists.
Centering is used to support slab & beam bottom , water tank ,chajjah & lintel bottom .
It can be done either in mild steel centering plates or plywood.
The form work gets used number of rimes for different buildings and therefore the regular maintenance is essential.
For shuttering sides are prepared in steel plates or plywood and it called making.
Securing the shuttering :
The method by which both centering and shuttering are supported is known as the staging.
Single Staging & Double Staging :
For roof slabs or beams at a height up to 10′ to 12′, it is possible to use Pipes of 10′ to 12′ in single lengths.This is called single staging.However, for further heights, it is not safe to only join ballies or pipes together .In such cases, a platform is first made at 10′ height > ballies and pipes are further erected on top of this platform .This is called double staging.
The platform made for workers and engineers to safely stand or sit or walk for working or for inspection purpose is called scaffolding .
The removal of centering & shuttering after certain specified days is called as strike-off or De-shuttering .The period after which it is removed is called de-shuttering.
While striking off it is a general tendency to throw the plates or other material to the ground floor which is a safety hazard and also damages the material .It must be strictly discouraged.
Some more terms:
Form finished concrete:
Sometimes for aesthetic reasons it may be decided to keep the concrete as it is without doing any plastering.In such cases the centering is done with new plywood sheets so that the concrete surface is neat & clean without any blemishes.Such concrete is known as form finished concrete .
The precautions taken during Form work ensure that the geometry ,line ,level and finish of the concrete are exactly as specified. A negligence in proper checking of form work means extra costs spent on breaking the extra edges, swollen surfaces and leads to added finishing cost.