What is FormWork in construction

Formwork refers to a mold made of rigid materials such as timber or steel plates in which concrete is placed and hardens.

Formwork is typically made of low-cost timber planks.

These are combined or adhered together to form the necessary mold for structural members such as beams, slabs, columns, foundations, and so on…

Steel formwork is used in the form of plates that can be bolted together to form various molds of various shapes.

Shuttering, Centering, Staging, and Scaffolding are all components of formwork.

1. Shuttering

Shuttering is a vertical temporary arrangement used to bring concrete into a specific shape.

Shuttering is a type of formwork that allows for vertical arrangement.

Shuttering is a type of formwork used for columns, footings, and retaining walls.

2. Centering

Centering is a temporary arrangement and component of formwork used to support horizontal members.

Centering is the technical term for the formwork for floor beams and slabs.

3. Scaffolding

Formwork is used to support structural members, while scaffolding is used to provide a worker’s platform around the building for working at heights.

Scaffolding can be movable or fixed, depending on the application and site conditions.

4. Staging

Staging includes items such as wooden balls, pipes, props, and jacks that support both shuttering and centering.

FORM WORKS ARE USUALLY MADE UP OF TWO PARTS.

1. A mold or a platform.

2. A system of support or centering.

MATERIALS APPLIED TO FORMWORK –

The materials used in the formwork are determined by availability and cost.

Formwork is primarily made of three materials.

1. Timber

2. Plywood

3. Steel

THE NEED FOR A GOOD FORMWORK

The following are the primary factors that can ensure good formwork.

1. Quality

2. Safety

3. The economy

Let us now go over all three major points in detail...

1. Quality

The formwork should provide correct right angles and a plane surface in order to reduce finishing costs after the formwork is removed.

The formwork should be leakproof to prevent cement slurry from leaking and causing honeycomb and segregation after removal.

2. Safety

Formwork should be strong enough to withstand dead and live loads during construction and when pouring concrete to avoid accidents and hazards to the structure or workers.

The joints should be rigid enough to prevent the formwork from sagging.

3. The economy

The cost of construction should not be prohibitively expensive.

It should be easily removable and undamaged so that it can be used repeatedly.

1. Timber as Formwork Material

Timber is the most commonly used formwork material. Timber logs, lumber, and other similar materials have been used as bracing members since ancient times. As a result, timber formwork is also known as traditional formwork. It is the most cost-effective formwork material. For a number of years, this has been used as a formwork material on construction sites, so the method of constructing a timber frame is well known to the workers.

Advantages

• Timber can be easily cut to any size required.
• Timber is light in weight and easily handled.
• Timber has good thermal resistance, which keeps concrete from cracking in colder climates.
• Because the construction method of timber formwork is simple, skilled workers are not required.
• It is simple to replace damaged timber forms.
• Timber formwork is simple to dismantle.

Disadvantages

• Dry timber may absorb water from wet concrete, reducing the strength of the concrete structure.
• When wet timber with a high moisture content compresses wet concrete and forms cracks in the structure,
• the grout may leak through joints.
• Timber forms have a limited application. As a result, they are no longer useful.

2. Plywood as Formwork Material

Plywood, a manufactured timber product, is also used for formworks. It is made up of layers of veneer sheets or plies. Nowadays, plywood formwork is increasingly being used, particularly for facing panels. The reason for this is that plywood formwork provides a smoother finish than standard timber formwork. As a result, the use of plywood may reduce finishing costs. Exterior plywood is a special type of plywood used for formwork. To make it watertight, the veneer sheets of exterior plywood are bonded with a strong adhesive. The thicknesses of the plywood boards range from 7mm to 32mm. In general, plywood 1220 x 2440 and 18mm thick boards are adequate for the majority of the projects. Special types of plywood with sufficient thickness are also available for curved structures.

Advantages

• Plywood can also be easily cut to the required size.
• Plywood is Strong, long-lasting, and lightweight.
• Provides a smooth surface finish.
• Very large plywood sheets are available, making formwork construction faster and easier.
• Plywood can also be used to create curved formworks.
• It has a higher number of reuses than timber.

Disadvantages

• It is more expensive than wood.
• Thin plywood sheets cannot support the weight of concrete and may bow out if the adequate thickness is not provided.

3. Use of Steel as a Formwork Material

Steel can also be used for formwork. It is very expensive, but it can be used more times than others. They give concrete surfaces an excellent finish. Steel from work is extremely strong and safe for mass structures such as dams and bridges.

Advantages

• Steel forms are more robust and long-lasting.
• The structure has a uniform and smooth surface finish.
• Excellent reusability.
• The formwork is simple to install and disassemble.

Disadvantages

• The price is significantly higher.
• Large structure formworks, it is heavy and requires lifting equipment.
• Corrosion occurs when metals come into contact with water on a regular basis.
• Forms come in a variety of sizes and shapes.

4. Use of Aluminum as a Formwork Material

Aluminum formwork is commonly used for prefabricated formworks. It is becoming more popular due to its lightweight and high strength. There are fewer supports and ties required.

Advantages

• Simple to assemble and disassemble.
• Because of its lightweight, it is easily handled.
• It can be reused numerous times.
• Structures’ walls and slabs can be cast at the same time.
• Aluminum formwork can be used to construct monolithic crack-free structures.

Disadvantages

• The lighter sections may deflect when the load reaches its maximum limit.
• When aluminum formwork is used, architectural modifications are not possible.