What is Formwork?

In a nutshell, formwork is the mold wherein fresh concrete is poured and formed. The mold, which can be permanent or temporary, holds the poured concrete and shapes it until it solidifies and becomes strong enough to support itself and other loads.

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Formwork is also known as “shuttering.” However, in certain parts of the world, shuttering refers to using plywood or timber to create the mold.

Formwork systems can be classified according to the following parameters:

• Types of material used to create the mold (plastic, steel, timber, aluminum)
• Types of concrete structure it supports (slab, column, wall)

Construction costs usually consist of building materials (ca. 45%), labor (ca. 45%), and operating expenses (ca. 10%). Formwork material comprises 15% of the total building material and contributes roughly 44% of the total labor. Meanwhile, formwork construction accounts for up to 25% of the total cost of building the structure. For this reason, many builders and construction companies prefer reusable forms (panel forms). The process of removing formwork is called “stripping.”

2. Column

As the name suggests, column formwork is used in the construction of circular or rectangular columns. Columns have formwork sections with a “closed load transmission,” which is supported by the formwork’s design and the guaranteed tensile strength rather than by using ties.

Steel formwork is often used to form circular columns as it is economical and available in incremental dimensions. Single-use forms, which are destroyed and disposed of during stripping, can be used as an alternative. However, using single-use formwork is not advisable if you need to construct multiple circular columns.

Meanwhile, rectangular columns are formed using three systems depending on their specifications. For instance, classic timber girders with steel walers and a plywood facing are often used when builders need to construct a significant number of columns with special dimensions. The windmill system, which is composed of columns or multipurpose panels of frame formwork systems, is suitable for building single columns with a standard dimension.

Finally, a foldable column formwork is highly suitable for columns with great heights. Because all the essential components (panels, connecting devices, ladders, and access platforms) are integrated into this type of column formwork, it helps builders reduce their construction time and costs.

3. Wall

Wall formwork comes in different types and classifications, as outlined below.

Conventional
Conventional wall formwork consists of boards or sheets and squared timber. It is flexible, but it can be costly and time-consuming as each component must be assembled on-site. In addition, all of its parts should be made according to the project’s specifications, and they must be nailed together and dismantled again after concreting.

Girder

This is a better version of the conventional formwork. Its components, which usually consist of dimensionally stable girders with two chords and one web, have been standardized to facilitate the assembly of identical and ready-to-use panels. The connection of the panels has also been systematized.

Frame
This type of wall formwork helps reduce labor time since its essential components (forming face, support for forming face, and steel walers) are assembled as one panel. The profile nose of the frames protects the edges of the forming face, thereby extending its lifespan. Connecting devices are used when assembling the frame panels to large-sized units, which are then usually transported by crane.

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Crane-independent (hand-set)

This type of formwork can be moved by hand. Because of weight considerations, it is usually made of aluminum or plastic. It can take less concrete pressure than crane-dependent formwork, and is often used in housing and municipal construction projects.

Crane-dependent 

Crane-dependent formwork systems feature a large frame and formwork panels, usually made of steel. As a result, they cannot be moved manually. Since they can resist more fresh concrete pressures than crane-independent forms, they are suitable for the construction of commercial buildings and other extensive infrastructure projects.

Two-sided
As the name implies, two-sided formwork is erected on both sides of the wall. Its formwork ties, which are usually sleeved by spacing plastic tubes so they can be reused, take up the fresh concrete pressure. Push-pull props or large heavy-duty braces are attached to the formwork to align and secure it against wind loads during operation.

Single-sided
Single-sided formwork is used when the concrete has to be poured against existing structures or when builders need to do concreting against a hill or soil. This is why it is most suitable for reconstruction jobs. With this type of formwork system, concrete pressure is transferred from the formwork to the base plates through a support structure. 

Prefabricated
This formwork consists of two prefabricated concrete panels which are assembled in advance, and then transported and filled with concrete on-site. Braces and push-pull props are often used to secure the walls, while working and safety scaffolds are installed with the help of special adapters to make the construction process more cost-effective. Prefabricated formwork helps minimize project duration and labor costs. However, pre-planning is required to ensure that it is transported safely to the site.

Circular
Circular formwork is designed for the construction of curved and polygonal walls. It is also quite useful in the construction of specific concrete structures, such as septic tanks and car park ramps. This formwork system comes in three different types:  

• Round girder – timber spacers are added between the timber girders and steel walers so the formwork can be adjusted to the required radius. 
• Flexible girder – ideal for the construction of curved walls with different radii. It comprises timber/steel girders and a spindle, which allows builders to adjust the formwork to the required radius without having to reassemble the panels.
• Polygonal – existing “flat” frame formwork panels can be refurbished as polygonal formwork by adding supplementary radius panels and rails, allowing builders to minimize their project costs.

Climbing
Climbing formwork is quite useful in the construction of high-rise concrete structures, such as control towers and skyscrapers, because it climbs with the wall. It comprises large wall formwork mounted to a climbing scaffold. There are three different types of climbing formwork:

• Crane-dependent – the climbing unit (scaffold and formwork) requires the use of a crane to reach the next cycle.
• Self-climbing – an automatic climbing system that does not require the use of a crane to reach the next suspension point. Hydraulic rams/pumps lift the scaffold, secondary platform, and formwork to the next pouring cycle. It is ideal for the construction of very tall concrete structures.
• Slipform – a two-sided formwork that slides upwards along the structure being built at a rate of 20–25cm per hour. A system of pipe rods, which is integrated into the already-set concrete, supports the slipform.
   

MEVA is an industry leader offering a wide variety of wall formwork systems that provide highly efficient shuttering, flexibility, and reliability. Our products are lightweight and easy to assemble, and therefore will facilitate the rapid completion of your construction projects. Click here to learn more.

A Quick Guide to Common Formwork Materials

Concrete formwork systems are built using a variety of materials. They all have their pros and cons, and different options are better for different projects, site environments, and construction needs. Below is a look at the most common formwork materials and the conditions they’re best suited to.

Capabilities of Good Formwork Systems

First, there are certain qualities that make common formwork materials useful in construction with concrete. Every formwork system must be:

• Capable of holding the load of wet and dry concrete

• Able to retain its shape with proper bracing

• Leak-proof at the joints

• Made of materials that don’t warp or become otherwise misshapen

• Removable without damaging the concrete (when using a removable system)

• As lightweight as possible

Types of Common Formwork Materials

• Timber formwork – Timber is a good formwork material because it’s lightweight and easy to work with, and it can be used to create formwork of any size and height. It’s very economical for smaller projects, but not particularly efficient for large ones. Also, it’s not suitable when flexible formwork is needed for complex concrete pours. Timber must be confirmed to be free of termites, and it does have a relatively short lifespan.

• Plywood formwork – This manufactured wooden material is often used in conjunction with timber for formwork systems. It’s durable and lightweight, and mostly used for sheathing, decking, and form lining.

• Steel and aluminum formwork – While considerably heavier and more costly than wood formwork, steel and aluminum are much stronger, longer lasting, and waterproof. They reliably create a smooth finish on the concrete and reduce the honeycombing effect, plus they can be used to form curved walls. Aluminum is not quite as strong as steel, but it’s also lighter.

• Plastic formwork – Plastic formwork systems are put together with modular or interlocking components. They’re best suited to smaller projects with a lot of repetitive formwork needs. Plastic is light and easy to clean. However, because these systems have many prefabricated components, they’re less versatile.

• Fabric formwork – These systems use lightweight, high-strength fabric sheets to allow for exceptionally flexible formwork. It’s a newer formwork material, but it’s quickly becoming popular for creating unusual shapes and interesting architectural details.

• Stay-in-place formwork – This type of formwork is left in place to provide axial and shear reinforcement, and to help prevent corrosion and other environmental damage. Primarily used for piers and columns, this formwork is assembled using prefabricated plastic components.

• Permanent insulated formwork – This formwork system remains in place and doubles as insulation that enhances the structure’s energy efficiency. More advanced materials also offer other benefits, such as fireproofing, sound dampening, and rodent resistance. Insulating concrete forms are the most common type, using polystyrene boards as insulation.