What is formwork?
Formwork is a mould used to restrain liquid concrete while it sets, allowing it to take shape and solidify. It is usually made of plywood and reinforced with horizontal wooden beams or wailings. This formwork is essential to creating the desired shape and structure of a concrete pour.
How Does Formwork Work?
Formwork works by providing a smooth surface which supports the concrete as it sets. It also transfers the considerable forces imposed by the dense liquid to a solid support, usually through the use of falsework. This ensures that the structure of the concrete pour remains in place and sets to the desired shape.
What is Falsework?
Falsework is a mechanism that is used to transfer the loads from the formwork to a solid support. It is an important part of the formwork system, as it is responsible for ensuring that the concrete sets correctly and that the formwork provides adequate support. Falsework can be performed using a variety of methods, depending on the type of pour and the structure that is being built.
Good Formwork:
The Importance of Quality Formwork: Formwork is an essential element for any concrete structure, and its quality is essential to get a good finish. The cost of fabrication, erecting and striking the formwork often exceeds the cost of the concrete itself, and formwork usually needs to be used multiple times for it to be cost efficient. This means that it needs to be handled, cleaned and stored with care.
Drawings for Formwork: For any large-scale concreting jobs, a drawing should be provided that shows what formwork is required. This does not need to be an intricate design drawing; a simple sketch should be sufficient.
It is important to inspect the formwork prior to pouring the concrete, as the face of the concrete is a negative of the formwork face. Poorly constructed formwork can lead to a poor finish, as is seen in the picture below, where paint has run off onto the concrete.
Good formwork should fulfill the following criteria:
- Strength and Durability: Good formwork should be robust enough to support the weight of fresh concrete during placing and compacting, as well as any other loads it may need to take. It should also be of a high enough quality for its intended use.
- Ease of Erection and Striking: Formwork should be easy to erect and take down with the equipment available. It should also remain stable in all kinds of weather conditions.
- Safety: The formwork should be handled safely and easily with the equipment available. It should also conform to all appropriate safety regulations.
- Seamlessness: The joints between the formwork members should be sound enough to prevent grout leakage.
- Accessibility: The formwork should provide suitable access for placing and compacting the concrete.