Formwork or shuttering is a common term used in the construction sector. Shuttering is a temporary casing used for fresh concrete to give it a specific shape and is stripped once the concrete sets. It is made up of different materials such as timber, steel, plywood, plastic, metal, etc., and provides support to wet concrete until it becomes strong enough to support itself.
Formwork can be assembled in various shapes and sizes, depending on the place of use. Generally, 20-25% of the total cost of the structure goes into shuttering. Since it is no longer needed once the construction work is complete, it is advisable to use economic types of framework to reduce the overall cost of construction.
Shuttering manufacturers use various materials to build shuttering, some of which are given below:
- Wooden shuttering
- Plywood shuttering
- Steel shuttering
- Reinforced concrete shuttering
- Wood-steel shuttering
Let us see where these shuttering are used?
- Timber shuttering – The conventional timber framework is used for small ventures that require less repetition. Lightweight timber without any knots and does not split when nailed is ideal for making shutters. These shuttering can be used ten to twelve times.
- Plywood shuttering – Plywood shuttering can be used twenty to twenty-five times and gives a smooth finish to the desired structure. Moreover, it can be used to cover large areas at a time, thus reducing the cost of erecting and dismantling again and again.
- Steel Shuttering – Steel shuttering may seem expensive in the first instance but is quite economical in the long run. It is more durable than other materials and gives a perfect finish to the structure.
Although timber shuttering is cheap, there is a risk of shrinkage, warping, and swelling. This can be reduced considerably by applying water-resistant coating on the shuttering. Steel shuttering is by far the most preferred form of shuttering as it gives proper support and shape to the concrete and is aesthetically pleasing too.
Let us look at some other advantages of using steel shuttering.
- Steel formwork helps in casting edges and specific shapes in the structure.
- Steel shuttering is highly rigid.
- The final structure has a smooth finish.
- Steel shuttering can be easily stripped once the concrete has been set.
- It is ideal for repetitive use.
An ideal shuttering should fulfill the following requirements:
- It should be economical to use.
- It should be strong enough to uphold the load of concrete and withstand the load of pouring and ensuing vibrations.
- It should be lightweight so that it can be easily assembled and stripped.
- It is important to ensure that there is no leakage in the joints.
- It should be rigid enough to have negligible deflection.
- The shuttering should be waterproof so that there is no absorption of water from the concrete.
As shuttering is only needed initially while construction, it makes sense to take shuttering on rent and save on the cost of dismantling and storage till further use.