You drive past a high-rise office building in the midst of construction, a skeleton slowly filling out with hard-hat-wearing workers pounding away. You notice a hose extending from a cement truck into a stack of panels that towers high and almost resembles a giant window pane, and you might scratch your head. What are those panels for? It turns out they're crucial components of construction called formwork.
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Formwork is the name for the molds used to create walls, columns, slabs, staircases and other concrete structures. Freshly poured concrete -- a combination of sand, gravel, cement, and water -- is wet, so it can't support its own weight or hold its shape. Formwork supports the weight of the concrete until it has dried into a specified shape and acquired the strength to support itself. "It's like when you bake a cake," says Harry Stamaty, owner of the formwork design and consulting business Detail By Design. "The pan that you put the cake in is the form, and the cake mix is the concrete" [source: Stamaty].
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The concept of formwork is nothing new. The Pantheon, a domed icon of Roman architecture built around 125 AD, was one of the earliest structures to use concrete formwork in its construction. But formwork remained a fairly uncommon tool and technique for the next several centuries – cement and concrete were rare building materials until the inventions of Portland cement and reinforced concrete in the 19th century [source: Stewart].
Today, formwork is used to build everything from office buildings to single-family homes, from driveways to sports stadiums -- basically, any structure that incorporates concrete. But formwork is rarely a part of the final design. Forms are temporary structures, a variety of construction agents that provide access and support during the creation of the project's permanent features before being removed or discarded [source: Nemati]. But as we'll see, even though formwork is intended to come and go without a trace, it's an important facet of the building process -- one that threatens grave consequences for carelessness.
Let's take a look at some of the materials used to make formwork.
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Forms, or the molds used to build formwork, have countless permutations. They can be derived from timber, plywood, steel, plastic, fiberglass and a variety of other materials. The way they're erected on a job site can vary, too. Sometimes formwork can arrive as a series of panels, along with hardware like ties, wedges, clamps, braces and brackets, which workers assemble by hand. On other occasions, prefabricated forms designed and built in a factory can be shipped to a job site, hoisted to the right position with a crane, and connected with simple locking mechanisms. Collaboration between the project's architect-engineer and the concrete contractor often determines the best formwork setup. Maybe plywood better accommodates crucial details of the concrete structure; maybe it would prove more economical to reuse forms that the contractor has stockpiled from a previous job.
All formwork must account for two key factors: the rate of pour and lateral pressure. The rate of pour is literally the speed at which concrete is poured into the vacancy of the form. Wet concrete is heavy, weighing roughly 150 pounds (68 kilograms) per cubic foot. As the vertical height of the poured concrete increases, the substance exerts lateral pressure as it pushes against the interior faces of the form. If too much concrete is poured at once, and the connecting devices aren't strong enough to contain the pressure, the wet concrete can burst through the form.
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The concrete poured at the bottom needs time to set and gain adequate strength before additional concrete is poured on top. Stamaty says that a rate of pour of 4 to 5 feet (1.2 to 1.5 meters) per hour is a good guideline to follow for virtually any formwork system, meaning a 12-foot-tall (3.7-meter) wall would take up to three hours for the full pour [source: Stamaty].
How exactly is formwork put into action on a construction job? Turn the page to find out.
Watch the WeatherThe rate of pour can change depending on the season: Ambient temperature affects the speed at which concrete sets, so the rate of pour is likely to be higher in the summer and lower in the winter.
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Formwork accounts for roughly 40 to 60 percent of the concrete budget for a given project [source: Lab]. Materials actually comprise a small part of the expense of formwork: Most of the money is spent on the labor to assemble and dismantle forms. Here are the basics of how formwork is used on the job site.
After the contractor and architect-engineer have looked at the structural and architectural drawings of a project and considered the form materials available to them, they'll select a formwork system, which, as mentioned earlier, either arrives in component pieces or already assembled. Once the formwork has been erected, workers must treat the interior of the molds with a release agent -- a compound made from wax, oil or plastic that prevents the form from sticking to the concrete -- because untreated forms can cause the surface of the concrete structure to become discolored or misshapen, which just requires more work to fix it.
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Once the form is in place and the concrete mixture is approved, workers begin pouring the concrete into the form's vacant space. (Representatives from the company supplying the concrete are usually on-site during larger commercial projects.) The concrete is distributed by hand or through a hose connected to a concrete truck, with a pump helping the concrete reach portions of the project where the truck can't travel. After the pour, workers often use industrial vibrating devices, which can either attach to the exterior of the form or be placed in the thick of the concrete. Vibration helps consolidate the elements of the concrete and eliminate air pockets. If necessary, the construction works can treat the concrete with water or steam.
After the concrete has dried, the forms are disassembled and removed, or "stripped" in construction parlance. The form can be repositioned in another area of the job site, stockpiled for later use or, if necessary, destroyed. These days, most forms are designed and built to be reused dozens of times.
Effective formwork has to balance several competing interests. Click ahead to find out what they are.
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A common sentiment in the concrete industry is that formwork should balance quality, cost and safety. In terms of quality, forms should accurately create concrete structures to the architect-engineer's specifications, without causing bulges or other defects to the surface of the concrete. In terms of cost, we already mentioned that formwork comprises a good chunk of the project's concrete budget. Failure to finish formwork in a timely fashion can also delay the rest of the construction schedule and lead to additional labor expenses, giving concrete workers an incentive to work efficiently.
But safety trumps all. About 25 percent of all construction failures result from collapses and failure of concrete structures, and formwork failures account for more than half of the figure [source: Hanna]. In December , a slab collapsed during the pouring of concrete during a casino construction project in Cincinnati, Ohio, resulting in several injuries to workers on the job site. The following month, another slab at different casino construction site collapsed during the concrete pour in Cleveland, Ohio [source: Feran].
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Formwork has also caused hundreds of deaths on construction sites [source: Nemati]. In Bailey's Crossroads, Va., in , workers removed the shores -- the supports that hold up horizontal slabs while the concrete sets -- from the 24th floor of an apartment building too early, triggering the collapse of the entire building, killing 14 workers and maiming many others [source: Hurd]. Forms can collapse from overloading with concrete, inadequate bracing, inadequate shoring, insufficient strength in the concrete before removal of the formwork, improper stripping and a host of other reasons.
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Organizations like the Occupational Safety and Health Administration issue guidelines for designing and working with formwork. Having supervisors on site during the erection of the forms and the pouring of concrete can help minimize the hazards of using formwork. If the formwork design needs to be altered, contractors should consult the form designer ahead of time. Formwork might be a temporary structure, but its consequences to the structure and those who build it can be permanent.
For lots more information on the construction process, see the links on the next page.
SlumpTo measure the relative strength of a batch of concrete, contractors will gauge its slump. Basically, they'll scoop a sample of concrete from the batch in a one-foot-tall (3.7-meter) cone, lift the cone and let the concrete to fall into a pile, and then measure the difference between the height of the cone and the height of the concrete pile. A difference in height of 3 to 4 inches (7.6 to 10.2 centimeters) is ideal, Stamaty says. "If it's a 10-inch slump, it means there's too much water in the concrete mix, which means it's really weak" [source: Stamaty].
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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.
To ensure the success of your construction projects, it is imperative that you only utilize a high-quality and reliable concrete formwork system. This will help ensure consistent and superior concrete finishes every time, and enable you to reduce your construction time and labor costs. At the same time, it will allow you to maximize your savings as concrete formwork reduces—if not eliminates—the need for additional plastering work.
At MEVA, we offer a wide selection of formwork systems for all types of concrete developments, including walls, columns, and slabs. Whatever formwork system you need for your project, you can be sure to find it at MEVA. However, please bear in mind that formwork systems can be quite diverse. We urge you to carry out some research and consult our formwork specialists here at MEVA. With our expert input, you can avoid costly mistakes and obtain the building concrete formwork that will meet your specific requirements.
At MEVA, we are always striving to refine our design and manufacturing techniques to ensure our customers only use the best and most reliable formwork systems. Please take a look at the concrete formwork solutions we have on offer to see which of them will enable you to get the job done in the quickest and most efficient way.
At MEVA, we have a comprehensive portfolio of heavy and light formwork systems for concrete wall developments of all sizes and specifications. We also have forms for curved structures to enable you to complete a wide range of concrete building and infrastructure projects with unique architecture.
Tough and versatile, our wall formwork systems are easy to assemble and handle. For instance, the MevaLite can be set by hand or with the help of a crane for ease of use and maximum efficiency. Best of all, our wall formwork systems have an excellent load capacity to allow for high pour speeds.
For more information about our formwork solutions for concrete wall developments, please visit our wall formwork page.
When building curved walls and circular columns, a particular type of formwork is required. At MEVA, we offer concrete formwork systems designed for developments with unique geometries. Our circular and column formwork systems are highly versatile and can be easily adjusted to conform to a concrete structure’s required curvature or radius. They also feature reliable facing/panels to ensure high-quality and consistent concrete surfaces.
Moreover, MEVA’s circular formwork systems are easy to set up and transport. This allows constructors to focus their time and energy on building the structure rather than on installing the required formwork. For example, the MAR, our highly flexible system for curved walls, can be easily assembled and fine-tuned on-site to accommodate a wide range of radii due to its adjustable waler.
To learn more about these systems, please visit ourcircular + column formwork page.
From classic climbing scaffolds to automatic climbing formwork systems, MEVA offers a wide range of form solutions for high-rise construction projects. Our climbing concrete formwork systems are made from high-quality materials and feature robust components to ensure efficient and quick climbing even in challenging conditions.
Regardless of the specifics of your projects, you can be sure that MEVA has the climbing formwork to meet your needs. We have both crane-dependent and automatic or self-climbing systems. For instance, if you want the best of both worlds, the MGS screen system can be lifted hydraulically or by a crane.
As with all of MEVA’s concrete formwork systems, our climbing forms are highly flexible and offer an outstanding level of safety and efficiency.
Please view ourclimbing formwork page and discover why our product offerings are a cut above the rest.
If your project requires the construction of horizontal concrete surfaces with smooth finishes, MEVA has precisely what you need. We provide an intelligently designed concrete formwork system for slab projects of all specifications, sizes, and thicknesses. Highly flexible, our formwork system can be adjusted with ease to match any building geometry, allowing you to save on time, labor, and materials.
Our slab formwork system is easy to handle for more ergonomic, efficient, and cost-effective work. Furthermore, cleaning and maintenance is a breeze due to the reduced concrete adhesion.
Explore the unique features and specifications of our slab formwork system by visitingthis page.
You can use MEVA’s props and shoring systems with our slab forms for maximum safety, efficiency, and flexibility of on-site operations. Solid and dependable, our props and shoring systems have excellent load capacity and can support a significant amount of loads and slab thicknesses. They also have a wide array of built-in safety features to ensure the well-being of your team on the ground.
Please take a look at ourprops and shoring systems page for more information.
Choosing a reliable formwork system is crucial if you want to complete your concrete developments in a fast, efficient and cost-effective way. At MEVA, we offer an extensive range of formwork systems to help you build high-quality concrete structures with consistent and superior finishes. With our products, you will be able to construct buildings with impressive geometries while making significant savings on your overall costs, materials and project duration.
If you want to find out more about our product offerings, please get in touch with our formwork specialists to discuss your requirements. To send us a message, use the contact information below or complete the form on this page.
Contact us to discuss your requirements of Concrete Column Formwork. Our experienced sales team can help you identify the options that best suit your needs.