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Short note: Formwork

Short answer

Formwork is a temporary mould of timber, plywood, steel or aluminium into which fresh concrete is placed to obtain the required shape. It must be strong, rigid, leak-proof, easy to strip and re-use, with smooth oiled surfaces. Stripping times per IS 456: vertical sides 16-24 hours, slab soffits 3 days, beam soffits 7 days.

Write a short note on form works.

Formwork (shuttering or centering) is a temporary mould, made of timber, plywood, steel or aluminium, into which fresh concrete is placed to get the required shape. It stays in place until the concrete gains enough strength.

Requirements

  • Strong enough to carry the weight of wet concrete, workers and vibration.
  • Rigid and stable, with little deflection.
  • Tight joints, to stop leakage of cement slurry.
  • Easy to erect, strip and re-use.
  • Smooth inner surface, treated with mould oil.
  • Economical and accurate in dimensions.

Types by material

Timber, plywood, steel, aluminium, plastic and fibreglass.

Components

Sheathing, studs/joists, walings, props, braces, ties, sole plates and wedges.

Stripping time (IS 456, OPC)

Vertical faces: 16-24 hours; slab soffits: 3 days (props refixed); beam soffits: 7 days (props refixed); props to slabs: 7 days up to 4.5 m span, 14 days over 4.5 m; props to beams: 14 days up to 6 m span, 21 days over 6 m.

✓ Answer checked by Claude Opus 5.5 (high effort)

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