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
- Modern-Day formwork
- 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
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
- 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.
- 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.