Formwork/Shuttering

Introduction of Formwork

  • Formwork is a mould or open box, like container into which fresh concrete is poured and compacted.
  • When the concrete is set, the formwork is removed and a solid mass is produced in the shape of the inner face of the formwork.
  • It should be capable of carrying all imposed dead and live loads apart from its own weight.

Requirement of a good formwork

  • It should be strong enough to withstand all types of dead and live loads.
  • The joints in the formwork should be tight against leakage of cement grout.
  • Materials should be cheap and reusable.
  • Light in weight, so that easy to transfer.
  • The joints in the forwork should be tight against leakage of cement grout.
  • Swelling and shrinkage should be minimum.
  • It should be practically water proof, so that it should not absorb water from concrete.
  • Deflection should be minimum.
  • The material of formwork should not warp or get distorted when exposed to the elements.

Categories of Formwork

  1. Conventional
  2. Modern-Day formwork
  3. Engineered/Pre-Fabricated Formwork

Major Objectives consdiered in formwork

  • Quality: Forms must be designed and built with sufficient stiffness and accuracy so that the size, shape, position, and finish of the cast concrete and amintained.
  • Safety: Forms must be built sufficient strength and factor of safety so that they have the capable of all supporting loads.
  • Economy: Forms must be built efficiently, minimizing time and cost.

Types of Formwork Materials

  • Timber
  • Steel
  • Plastic
  • Aluminium

Advantage of Timber formwork

  • Easy handling because it is light weight.
  • Easy to disassemble.
  • Damaged parts can be replaced with new one.
  • Very flexible.
  • Easy to produce.
  • Easily available.

Advantages of steel formwork

  • It can be used for a no. of times.
  • It is non absorbent.
  • Smooth finish surface obtained.
  • No shrinkage of formwork occurs.
  • Easy to use.
  • Its volume is less.
  • Its strength is more.

Advantages of Plastic formwork

  • Light weight
  • Reusable
  • Che,ical resistant
  • Can be easily cut and nail by using wood working.
  • Damages on the formwork can be easily removed.
  • Very useful for complex shaped and special features.

Advantages of Aluminium formwork

  • Quickly and accurately assembled.
  • Light weight component provides low pressure on the lower part of the buildings.
  • Faster construction cycles.
  • High quality finishes.
  • Can be easily recycled.
  • Safe work platforms.
  • High salvage cost.

Safety Precaution

  • Material used for the construction of formwork must fulfill the specification.
  • Formwork is fixed firmly and properly.
  • Cosntruction area must be protected to prevent vandalism of formwork.
  • Warning sign must be put up at the area where the formwork is fixed to prevent entrance of people that may damage the formwork.
  • The formwork must be inspected before the concrete is poured.

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