Formwork 101: An Introductory Guide
Concrete is one of the most versatile and widely utilised construction materials in the world. It is used to build a wide range of structures, from skyscrapers, bridges to monuments and dams. However, concrete cannot stand on its own. It must be poured into a particular type of mould. This is where formwork comes in.
What is Formwork?
In a nutshell, formwork describes the mould wherein fresh concrete is poured and formed. The mould, 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.
Formwork is also known as “shuttering”. However, in certain parts of the world, shuttering refers to using plywood or timber to create the mould.
Formwork systems can be classified according to the following parameters:
- Types of material used in creating the mould (plastic, steel, timber, aluminium)
- Type of concrete structure it supports (slab, column, wall)
Construction costs are made up of building material (ca. 45%), labour (ca. 45%) and operating expenses (ca. 10%). Formwork material makes up 15% of the total building material and contributes roughly 44% of the total labour, while formwork construction accounts for up to 25% of the total cost of the structure being built. For this reason, many builders and construction companies prefer reusable forms (panel forms). Meanwhile, the process of removing formwork is called “stripping”.
Types of Formwork Frame and Facing According to Material
As mentioned earlier, formwork systems can be made from a wide range of materials. This section will discuss each type, as well as its characteristics, advantages, and disadvantages.
Because it is inexpensive and easy to procure, timber is a common material used in creating formwork frames. It is also flexible and can be assembled on site. Timber is suitable for small projects and the construction of complete concrete sections that require flexibility.
However, timber is susceptible to termites. This is why it's vital to check the material before using it as formwork. Also, it absorbs moisture and has a short lifespan. It can easily warp, swell, and shrink. It cannot withstand large fresh concrete pressure and is not suited for repeated use. Because of this, it is not advisable for large and highly complex construction projects.
If you want a formwork frame that is as strong, durable, and reliable as steel but not as heavy, aluminium is certainly an excellent choice. It is lightweight and doesn't absorb moisture, so there is no warping or shrinking. Most importantly, it can be reused a significant number of times, helping you minimise construction costs while maximising your savings.
Besides the advantages discussed above, here are the other benefits of using an aluminium formwork frame:
Because it’s lightweight and mostly crane-independent, and helps to speed up the construction of the project. This allows you to save time and labour, and ultimately minimise overall costs.
It can have powder-coating to create an impact- and scratch-resistant surface and ensure easy cleaning.
It offers a cost-effective solution when building a significant number of symmetrical structures.
It can have welded-in nuts for easy and quick assembly of accessories, such as brackets or guarding rails.
It can be repaired and refurbished multiple times.
It has less concrete adhesion compared to other materials.
Similar to steel formwork, aluminium is relatively more expensive than timber or plywood. However, the long-term savings it can offer you will certainly make up for its initial cost. Also, with a wide range of aluminium formwork systems available today, such as the product offerings we have here at MEVA, finding the system that meets your specific needs and budget is fast and easy.
Steel formwork comprises panels fabricated from thin steel plates with hollow profiles. In most cases, the steel panels are held together by assembly locks or bolts and nuts.
Although using steel formwork is initially more expensive and may increase the overall cost of the project, it can offer long-term savings since it can be reused a significant number of times. Besides its cost-effectiveness, steel formwork also offers the following benefits:
- It is stronger and more durable than other types of formwork.
- It has powder coating and hot dip galvanising, which protects the metal against corrosion and fast wear.
- It can be quickly installed and dismantled with a crane.
- It doesn't shrink or warp.
- It lasts a very long time.
- It helps reduce overall costs when constructing a number of symmetrical structures.
- Similar to aluminium formwork, it can have welded-in nuts to make the assembly of accessories, such as brackets or guarding rails, easier.
- It provides the highest permissible fresh concrete pressure of up to 100 kN/m² with wall formwork.
- It has less concrete adhesion.
- It can be repaired and refurbished many times.
Besides being relatively more expensive, one known disadvantage of steel formwork is that it requires the appropriate lifting equipment to lift and transport the panels.
Plastic formwork is assembled by interlocking lightweight yet sturdy plastic panels or modular systems and suitable for concrete pouring of fundaments, small walls, pillars and columns. Similar to aluminium formwork plastic formwork is lightweight and thus crane-independent. Plastic formwork normally carry a plastic facing as well. The permissible fresh concrete pressure is relatively lower compared to metal formwork. Since plastic formwork is not as stable and torsionally stiff as metal formwork, more parts are needed to securely connect and align it, which in turn increases the labour time.
Often used with timber, plywood formwork facing is available in varying thicknesses and sizes. It is usually less expensive than steel facing. It is also lightweight and can be reused a few times.
To make plywood formwork facing, resin-bonded plywood sheets are attached to any formwork panel. However, while it is solid and generally dependable, plywood facing is not as long-lasting and durable as steel facing. Because it is made of wood, it can absorb moisture and be prone to swelling and warping.
Steel formwork facing is ideal for circular or curved structures. Also, it is often used for extensive projects and situations where it is possible to reuse the formwork many times. It provides outstanding exposed concrete surfaces, provided that it is properly applied and a suitable release agent is used.
Some of the most notable qualities of plastic-faced formwork are its durability and high bearing capacity. It is also lightweight and sustainable as it can be repaired and reused. For instance, MEVA's alkus all-plastic facing is quick and easy to repair. It can be recycled to nearly 100% and can be used for up to 1,500 times. In comparison, plywood cannot be recycled because of its high usage of glue. Easy to handle, alkus plastic facing is rigid yet flexible and can be bent and shaped with ease.
Types of Formwork Based on the Concrete Structure They Support
Formwork systems are used to support different kinds of structures. Each type has specific requirements and is named according to the building element it supports. Let's see what makes them unique from each other.
Any concrete structure requires a strong foundation, and a strong foundation requires the correct formwork. Foundation formwork, which is often made with standard wall panels, can be designed in many ways. However, the design must correspond to the type of foundation you are building, whether it is a column or a wall. Then you must determine the shape and size of the footing, which, in turn, helps you identify the correct formwork size and shape.
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 form a significant number of columns with special dimensions. The windmill system, which is composed of columns or multi-purpose panels of frame formwork systems, is suited 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 construction time and costs.
If you are looking for column formwork that features intelligent design and is developed to maximise safety in the workplace, you can't go wrong with the circular and column formwork systems we have here at MEVA. Our products are designed with optimum efficiency in mind to help builders save time and labour. To learn more about our column formwork systems, click here.
Wall formwork comes in different types and classifications, including:
It consists of boards or sheets and squared timber. It is flexible, but it can be costly and time-consuming since each component must be assembled on site. Also, all of its parts should be made specifically according to the project's specifications and must be nailed together and dismantled again after concreting.
It 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 standardised to facilitate the assembly of identical and ready-to-use panels. The connection of the panels has also been systematised.
This type of wall formwork helps reduce labour 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, thus, extending its lifespan. Connecting devices are used when assembling the frame panels to large-size units, which are then usually transported by crane.
This type of formwork can be moved by hand. Because of weight considerations, it is usually made of aluminium or plastic. It can take less concrete pressure than crane-dependent formwork and is often used in housing and municipal construction projects.
Crane-dependent formwork systems feature a large frame and formwork panels, usually 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.
As the name implies, two-sided formwork is put up 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 it and secure it against wind loads during operation.
Single-side formwork is used when 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. In this type of formwork system, concrete pressure is transferred from the formwork into the base plates through a support structure.
It consists of two prefabricated concrete panels, which are then assembled in advance and then transported and filled with concrete onsite. 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 minimise project duration and labour. However, pre-planning is required to ensure that it is transported safely to the job site.
It 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 different types: round girder, flexible girder, and polygonal.
- 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 – suited 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 re-assemble the panels.
- Polygonal – existing "flat" frame formwork panels can be refurbished as polygonal formwork by adding supplementary radius panels and rails, allowing builders to minimise costs.
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 is composed of large wall formwork mounted to a climbing scaffold. There are different types of climbing formwork. They are: crane-dependent, self-climbing, single-sided climbing, and slipform.
- Crane-dependent – the climbing unit (scaffold and formwork) requires the help of a crane to reach the next cycle.
- Self-climbing - an automatic climbing system that doesn't require a crane's assistance 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 efficient shuttering, flexibility, and reliability. Our products are lightweight and easy to assemble to facilitate the quick completion of your construction projects.
Similar to the foundation formwork, the design for slab formwork will depend on the type of structure being constructed.
Conventional slab forming with stringers and joists
A good example of the conventional slab formwork is MEVA's MevaFlex system, which consists of facings, crossings, and girder stringers on props or shoring towers. It offers flexibility and is suitable for a wide range of building layouts and slab thicknesses.
Modular slab formwork
Besides the system discussed above, there's a more modern method of slab formwork. It is called modular slab formwork, and a good example of this is MEVA's MevaDec System. MevaDec consists of panels with integrated facing, primary and secondary beams, and props with drop heads. The drop heads facilitate early stripping, which could help builders save as much as 40% on materials and speed up the completion of the project.
Three slab forming methods can be used with this formwork system. They are:
- Drop-head-beam-panel method (FTE) – uses only three components: panels, primary beams, and props with drop heads. In this method, the panels can be inserted and slid freely into place. It also makes it easier to strip the beams and panels and use them for the next pouring cycle, allowing builders to finish a slab in just three days.
- Primary-and-secondary-beam method (HN) – uses four components: primary beams, secondary beams, props with drop heads, and facings. This method allows for early stripping.
- Panel method (E) – uses only two components: panels and props with prop heads. This method is highly suitable for projects with small surface areas and simple logistics.
At MEVA, we offer slab formwork systems designed to help builders improve safety and enjoy maximum efficiency. Our products feature a lighter and more ergonomic design, and they can be adjusted easily to match any slab thickness and building design. Click here to learn more about our slab formwork systems.
Also known as "special forms", custom-built formwork systems are designed and manufactured specifically to meet a project's individual requirements. Rentable standard parts may also be integrated into the special forms, but at least some of their components should be custom-made and produced separately.
Custom-built formwork systems are generally used for concrete structures with complex architectural requirements that cannot be accomplished with only standard formwork systems. A combination of the following factors can help builders determine if they need to use special forms to complete a project:
- Building shape and size
- Job site location
- The formwork's load bearing capacity
- The concrete's surface quality
- Job site infrastructure/logistics
- Construction schedule
- Weather conditions in the job site
What Makes a Good Formwork?
To get the results you are expecting, choosing the best and most reliable formwork is vital. While sound formwork systems differ by material or the building elements they support, they share specific qualities that make them worthy of your time and investment.
Below are the qualities that your chosen system should possess:
- Exceptional load capacity
The formwork system should be strong enough to withstand any dead (e.g. the weight of the concrete structure itself and other permanent loads) and live (e.g. the weight of building occupants, vehicle traffic, equipment, and other temporary elements) loads.
- Outstanding shape retention capability
The formwork should be constructed rigidly and supported correctly by props and braces to retain its shape successfully.
- Leak-proof joints
Its joints should be tightly sealed to prevent cement from leaking.
- Does not damage the concrete
If the formwork is removable, it should be constructed so that various parts can be removed easily without damaging the concrete.
- Made from reusable material
A formwork system that can be repaired and reused multiple times, such as steel and aluminium, can help you minimise costs and maximise your savings. Also, it is friendlier to the environment
Formworks made of lightweight materials are easier and faster to transport and assemble, allowing you to save time and labour.
- Free from warping and distortion
To ensure optimum reliability, it shouldn't warp or get distorted when exposed to the elements.
Choose Only the Formwork You Can Trust
Formwork plays a vital role in the construction of concrete structures. Because they help ensure the stability and reliability of your projects, it makes perfect sense to choose systems made from quality materials and designed for maximum efficiency and reliability.
At MEVA, our goal is to provide our clients with formworks that are safe, efficient, and easy to use. We work day in and day out to ensure that our products meet our customers' specific needs and requirements. If you wish to learn more about our products and services, please fill out the form below, and we will get back to you as soon as we can.