FIND THE 'BEST' FORMWORK FOR YOUR PROJECT

Selecting the right forming system is an important decision for any concrete frame building project. Consider that the total load for a 12-inch-deep, 10,000-square-foot slab is more than 2 million pounds (concrete + live load + form load). The formwork system must temporarily support that load while reshoring distributed loads throughout the structure. While there are many ways to safely shore a supported slab, the goal is to find the best and most economical way.

To help determine the best system for every project type, Ceco Regional Manager Ryan Gregory provided an overview of common horizontal forming systems and the factors that drive system selection during a webinar for the Minnesota Concrete Council in November. Below are a few takeaways from Ryan’s presentation.

Each forming system has different advantages and disadvantages:

• Stick/hand-set consists of loose-framed members (lumber or aluminum) and is flexible and customizable. While good for accommodating odd shapes and sizes and on sites where a crane is not feasible, the system is both labor-intensive and material-intensive.
• Modular framing includes standardized panels and components. The system can be modifiable to most conditions, does not require a crane and can handle some slab profile changes/interruptions. However, it is material-intensive.
• Flying table/truss. Designed from steel and aluminum to provide a lightweight, high-capacity system with fast cycle times, flying tables and trusses are highly efficient but require a crane (hoisting-intensive). While labor cost are low using this system, equipment costs are high.
• Steel beam. Designed specifically for parking structures, with sections that bolt together to create one-piece beam forms and deck panels spanning from beam to beam, it is an efficient system with only a few components. It has a high equipment cost (hoisting intensive) and low labor cost.
• Column-mounted. This prefabricated system utilizes walls or columns for vertical support, reducing the need for vertical shoring components. While it eliminates reshores, the system relies on consistent column placement and requires a high level of formwork engineering.

Formwork system selection is most often driven by the building design. Other factors to consider include:

• Site conditions: staging area, make up area, ground conditions, air rights/neighbors.
• Consistency: structural system changes, footprint stepping in/out and story height changes.
• Tolerances: specified finish and exposed to view.
• Transfer conditions.
• Hoisting: crane capacity, reach, location and availability.
• Schedule: cycle times, out-of-sequence work, interruptions/delays.

Ryan also gave examples of building design factors that affect constructability and formwork economy. A consistent design leads to repeatability of forming systems—and repeatability saves money.

To learn more, download the webinar handout and contact us for help selecting the right forming system for your project. When Ceco is brought in early during the project’s planning, we can devise the most constructable design and the most efficient formwork system to save our clients time and money.

Concrete formwork systemsformwork 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.

• 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.