Formwork For Concrete
Trev Mailloux
Concrete is one of the most widely used construction materials, thanks to its exceptional properties. However, to create building elements with concrete, it must be poured into a specially designed mold. This is known as formwork or shuttering.
When selecting formwork it is important to consider the type of concrete and the pouring temperature, since both affect the pressure exerted. Also, formwork must be capable of resisting the loads of wet and dry concrete.
Formwork requires structures such as poles and stabilisers to avoid movement during construction procedures, and these are called falsework. To ensure high quality when working with concrete, a qualified workforce and adequate supervision are necessary.
However, before using timber its condition must be checked carefully, making sure it is free of termites. Timber formwork also has two limitations that must be considered: it has a short life span and is time consuming in large projects. In general, timber formwork is recommended when labor costs are low, or when complex concrete sections require flexible formwork.
Plywood is often used used along with timber. It is a manufactured wooden material, which is available in different sizes and thicknesses. In formwork applications, it is mainly used for sheathing, decking and form linings.
Steel formwork and steel hardware is becoming more popular due to its long service life and multiple reuses. Although it is costly, steel formwork is useful for multiple projects, and it is a viable option when many opportunities for reuse are expected.
Aluminum formwork is very similar to steel formwork. The main difference is that aluminum has a lower density than steel, which makes formwork lighter. Aluminum also has a lower strength than steel, and this must be considered before using it.
This type of formwork is assembled from interlocking panels or modular systems, made of lightweight and robust plastic. Plastic formwork works best in small projects consisting on repetitive tasks, such as low-cost housing estates.
Plastic formwork is light and can be cleaned with water, while being suitable for large sections and multiple reuses. Its main drawback is having less flexibility than timber, since many components are prefabricated.
Fabric formwork is also known as flexible formwork. This system uses lightweight and high-strength sheets of fabric, designed to adjust to the fluidity of concrete and create interesting architectural forms.
This formwork type uses less concrete than rigid systems, which yields savings. It is an emerging technology in the shuttering industry, especially suited for constructions of irregular and complex shapes.
This formwork is designed to remain fixed after the concrete has set, acting as axial and shear reinforcement. This formwork is made on-site from prefabricated and fibre-reinforced plastic forms. It is mainly used in piers and columns, and also provides resistance against corrosion and other types of environmental damage.
Tunnel formwork is a common construction method used in residential apartments & hotels which involves producing repetitive structural elements for buildings with the same layouts. It employs a steel formwork system that is built on the construction site to pour concrete walls and slabs in a continuous cycle. This strategy is especially effective for tasks that require quick construction and consistent design.
Tunnel formwork is extensively used in high-rise construction projects when speed and efficiency are crucial. The advantages are faster construction, high quality control, and less labor cost. The approach allows the creation of long-lasting structures fast and efficiently, making it one of the popular choices in the infrastructure industry.
This is one of the most advanced formwork systems, offering permanent insulation. It may also include thermal, acoustic, fire-resistance and rodent-resistance properties. Insulating concrete forms (ICF) are the most common type of permanent insulated formwork, where concrete structures are insulated with polystyrene boards that stay in place after concrete has cured.
All formwork types are designed according to the structure they support, and the corresponding construction plans specify the materials and required thickness. It is important to note that formwork construction takes time, and it can represent between 20 and 25% of structural costs. To mitigate the cost of formwork, consider the following recommendations:
Concrete structures vary in design and purpose. Like in most project decisions, no option is better than the rest for all applications; the most suitable formwork for your project varies depending on building design.
Form Tech carries a wide variety of Concrete forming systems and products allowing our experienced teams to quickly handle both standard and complex forming situations. We combine our industry leading products, field experience and jobsite service to meet most formwork requirements.
With a wide variety of filament types from affordable, general use materials to high-quality, engineering-grade materials for demanding industrial applications, BigRep has what you need - specialized for large-format 3D printing to bring your designs to life in full scale. Discover moreSoftwareBigRep CONNECT is a one-stop platform connecting you with your BigRep printers to boost productivity with remote monitoring and data analytics.
Concrete formwork in construction can make up 40 - 60% of a total budget, especially for complex shapes such as curved concrete forms. Some designs like organic shapes, double curved surfaces, and cavities are simply not feasible to produce because they require highly skilled laborers to produce customized formwork resulting in high costs, long lead times, and material waste.
BigRep 3D printers can produce large-scale, complex formwork up to 3x faster at a fraction of the cost of traditional methods. With the new CONCRETE FORMWORK filament developed by BASF Forward AM and BigRep, you can unlock the massive benefits of 3D printed formwork.
3D printed formwork is a perfect solution for casting complex geometries. The first step is to design and print the formwork. For restoration projects, it is also possible to scan existing elements to create the 3D models for the formwork.
If the formwork is larger than BigRep print volume (1m3 on the BigRep ONE, for example) then it can be printed in parts and assembled after. If needed, the 3D printed formwork can be post-processed with a variety of methods. It is also possible to combine traditional formwork for simple shapes with 3D printed formwork for complex parts. Then the concrete is cast using standard methods. Finally the formwork can be cleaned and reused.
The lateral forces and moments on the formwork have been easy to handle, but I'm trying to find a good approach to the vertical uplift hydrostatic force on small-scale/DIY formwork while concrete is poured, which is a general problem for which I can't seem to find a good solution.
I'm confident in the actual formwork - plywood backed by C16 2x4's (50x100 mm), which are in turn backed by 3x6's (70x150 mm) held together with heavy duty structural screws, 12mm s/steel threaded bar between the formwork timbers of the two faces, all the entire form ultimately being braced laterally against solid ground on both sides nearby.
My concern is countering the vertical uplift forces from the hydrostatic pressure of the fluid concrete when it's poured, which will be about 4 - 5 tons equivalent (40 - 50kN), ie the weight of the "missing" concrete above the slanted face of the form. Basically, I want it not to be lifted off the ground by the fluid concrete. I've thought of several possible approaches to offset this force, but the reality is that I'm just not sure which is best or most foolproof, or if there are standard solutions used in civil engineering that I'm unaware of.
I would say for smaller scales, a combination of methods would be easiest. I would try to pour in thin layers if your concrete supplier can handle it. Also place whatever you can on the form to help weigh it down (concrete blocks, etc).
This might be easier if you use a mix of concrete that isn't so fluid (not SCC). You will have to vibrate the concrete and you will likely have more honey combing on the sloped side, but that side will be buried anyway.
Fill it with water. It looks like it's solid on both sides and at both ends. Fill the water at the same time as the concrete -- you want the water level to be below the concrete level to avoid leakage and/or washout on the cement pour side. On the other sides a slow leak doesn't matter. After the concrete is poured, a slow leak on the concrete side won't happen (because of the greater pressure on that side), and won't matter (because it will only washout the surface).You may want to add more bracing -- your formwork will soften when wet.
Because the water is lighter, if won't be /sufficient/ to hold the formwork in place, but you can calculate how much of the force it will handle, and you will be able to use a cheaper and easier solution like adding 2 tons instead of 5 tons.
EFCO provides a wide range of formwork products to meet contractor needs in all concrete construction applications. Our products are safe, simple to use, rugged, and durable. They are designed to form concrete into many shapes, sizes, or configurations, and exceed your expectations with each use. EFCO formwork solutions will produce the lowest in-place concrete cost.
It looks like you are currently using Internet Explorer to view our site. To experience our site in its entirety, please use a newer browser. If you continue in Internet Explorer know that certain features and functionality are not supported on this site.
Formwork systems for concrete structures come in various types and specifications. They can also be made from different materials, such as steel and aluminum, and be equipped with a range of accessories to improve their functionality.
c80f0f1006