Requirement of good form work: 1. It should be strong enough to resist the weight of concrete, workers and machinery. 2. It should be economical compared to total cost of construction. 3. It should be possible to use the formwork for more number of times. 4. It should give smooth finish and shape to concrete faces. 5. It should be possible to erect and dismantle the formwork very easily. 6. It should be easily and locally available. 7. It should be rigid enough to retain its shape without any deflection.
Stripping time of form work as per IS 456-2000.
i) Slab:
1. Soffit formwork – 3 days
2. Span up to 4.5m – 7 days
3. Span more than 4.5m – 14 days
ii) Beam:
1. Soffit formwork for beam – 7 days
2. Beam and arch of span up to 6m – 14 days
3. Beam and arch of span more than 6m – 21 days
iii) Column: Vertical formwork – 16 to 24 hours