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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.
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.”
Frames
1. Timber
Because it is inexpensive and easy to procure, timber is commonly used to create 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, which is why it is vital to check it carefully before using it as formwork. In addition, it absorbs moisture and has a short lifespan. Timber can also easily warp, swell, and shrink. It cannot withstand large fresh concrete pressure and is not suited for repeated use. For this reason, timber is not recommended for large and highly complex construction projects.
2. Aluminum
If you want a formwork frame that is as strong, durable, and reliable as steel but not as heavy, aluminum is an excellent option. 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, enabling you to minimize your construction costs while maximizing savings.
Besides the advantages discussed above, other benefits can accrue from using an aluminum formwork frame:
- Because aluminum is lightweight and mostly crane-independent, it helps speed up the construction project. This allows you to save on time and labor, and ultimately minimize your 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 large number of symmetrical structures.
- It can incorporate welded-in nuts for easy and quick assembly of accessories, such as brackets and guarding rails.
- It can be repaired and refurbished multiple times.
- It has less concrete adhesion compared to other materials.
Similar to steel formwork, aluminum 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 aluminum 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.
3. Steel
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 your 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 galvanizing, 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 aluminum 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, another disadvantage of steel formwork is that it needs the appropriate lifting equipment to lift and transport the panels.
4. Plastic
Plastic formwork is assembled by interlocking lightweight yet sturdy plastic panels or modular systems. It is suitable for concrete pouring of fundaments, small walls, pillars, and columns. Similar to aluminum formwork, plastic formwork is lightweight and thus crane-independent. In addition, plastic formwork usually utilizes plastic facing. Its permissible fresh concrete pressure is relatively low 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 labor time.
Facing
1. Plywood
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 several 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.
2. Steel
Steel formwork facing is ideal for circular or curved structures. Furthermore, it is often used for extensive projects and when builders want to reuse the formwork many times. If it is properly applied and a suitable release agent is used, steel formwork facing produces outstanding exposed concrete surfaces.
3. Plastic
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 up to 1,500 times. In comparison, plywood cannot be recycled because of the 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 a variety of structures. Each type has its own specific requirements and is named according to the building element it supports. Let’s examine what makes them unique.
1. Foundation
All concrete structures need a strong foundation, and in turn all strong foundations need 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. You must then determine the shape and size of the footing, as this will enable you to identify the correct formwork size and shape.
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.
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.
4. Slab
Similar to foundation formwork, the design for slab formwork will depend on the type of structure being built.
Conventional slab forming with stringers and joists
Conventional slab formwork often comprises 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 is a more modern method of slab formwork available. It is called modular slab formwork and it typically 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 money on materials and enable them to complete their projects much more quickly.
At MEVA, we offer slab formwork systems that are designed to enable builders to improve their safety procedures and enjoy maximum efficiency. Our products feature a lighter and more ergonomic design, and they can be easily adjusted to match any slab thickness and building design. Click here to learn more about our slab formwork systems.
5. Custom-built
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 whether they need to use special forms to complete a project:
- Building shape and size
- Site location
- The formwork’s load bearing capacity
- The concrete’s surface quality
- Site infrastructure/logistics
- Construction schedule
- Weather conditions at the site
What Makes a Good Formwork?
In order to obtain the results you desire, it is imperative that you choose the best and most reliable formwork. Although 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.
Here are the qualities that your preferred 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 so it can retain its shape. - Leak-proof joints
The joints should be tightly sealed to prevent any cement leakage - Does not damage the concrete
If the formwork is removable, it should be constructed in such a way that the 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 one made of steel or aluminum, will help you minimize your costs and maximize savings. In addition, it will be friendlier to the environment - Lightweight
Formworks made of lightweight materials are easier and faster to transport and assemble, allowing you to save on time and labor. - Free from warping and distortion
To ensure optimum reliability, the formwork should not warp or become distorted when exposed to the elements.
Choose Only the Formwork You Can Trust
Formwork plays a vital role in the construction of concrete buildings. Because they help ensure the stability and reliability of your projects, it makes perfect sense to choose a formwork system that has been made from high-quality materials, and which is 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 requirements. If you want to find out more about our products and services, please complete the form below and we will get back to you as soon as we can.