Concrete is the prime material utilized in the construction process. This is because of its exceptional properties. But to make use of concrete in a building, it is vital to pour concrete into a mould that is specifically designed to create building elements with it. If the mould is made of aluminium, it is called aluminium shuttering or simply ‘Formwork’ with regard to other materials.
What is formwork?
When concrete is fresh and in a liquid state, it must be restrained within a mould such that it sets in the desired shape. This mould is referred to by the term- Formwork.
For most in-situ pours, the formwork is typically made of wood. A smooth outer surface offers main support for the concrete as it sets. This is mainly made of plywood. Concrete is nearly 2.4 times denser than water, and in its liquid form, it puts much force on the formwork encompassing it. Hence it is vital to reinforce the plywood with horizontal wailings or wooden beams.
If properly constructed, this mechanism of plywood skin supported by timber wailings offers generous support to set the concrete. The technique of transfer of such loads towards solid support can be conducted by many methods.
Material for wall formwork
Typically, formwork for walls is built upon on each side of walls. Wall formwork is the perfect choice for various kinds of vertical applications like shear walls, lift wall rafts, water tanks, retaining walls, etc. The several materials used for wall formwork include Plastic, Fabric, Aluminium, Steel, etc.
Out of such selections, plastic fabricated formworks are most popular. The reason behind their popularity is that they are easy to handle and lightweight. They are resistant to water and durable for long periods. Aluminium formwork system is lighter than steel and economical for repeated use.
There are 2 factors that determine how best the concrete will look in the final outcome: 1) how the concrete is placed and compacted and 2) the quality of the formwork.
Formwork is made of expensive materials and needs much experience and skills for its manufacture. Its importance is proven by considering the cost of fabrication, erection, and striking of the formwork. This often exceeds the cost of the concrete, which it is meant to support and shape.
Formwork typically needs to be used many times for it to be cost-efficient. This is possible only if it is handled, stored, and cleaned carefully, regardless of what material it is made of. For anything apart from the smallest of jobs of concreting (like walls of 1 m), drawings should be provided revealing what formwork is needed.
This need not be an intricate design drawing; a simple sketch will suffice. It is vital to note that the face of the concrete serves as a negative for the formwork face. Always inspect the formwork before pouring it into the concrete.
Good formwork features the following criteria:
- It is strong enough to support the weight of fresh concrete during placement and compacting and any other loads it has to take.
- The face of the formwork is of adequate quality for its use.
- It is adequately stable in all weathers.
- It can be easily struck and erected.
- It can be handled easily and safely using available equipment.
- It offers the right access for placing and compacting the concrete.
- It complies with relevant safety regulations.
In sum, these are the main features of formwork.
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