Shuttering, also known as formwork or molds, is a crucial aspect of constructing concrete slabs. It refers to the temporary structure or mold into which concrete is poured and shaped until it hardens and gains the required strength. Shuttering is an integral part of the formwork system used in concrete construction. Here are key points about the shuttering of slabs:
- Purpose of Shuttering:
- Shuttering provides a mold that defines the shape and dimensions of the concrete slab until it sets and can support its own weight.
- It supports the weight of fresh concrete, reinforcing materials, and construction workers.
- Types of Shuttering for Slabs:
- Traditional Timber Formwork: Wooden boards and planks are used to create the mold. This is a common and cost-effective method.
- Plywood Formwork: Plywood sheets are used as the facing material for formwork, providing a smooth finish to the concrete.
- Metal Formwork: Steel or aluminum panels are used for formwork. This type is durable, reusable, and suitable for large-scale projects.
- Plastic Formwork: Modular panels made of plastic are lightweight and easy to assemble, offering versatility in design.
- Components of Shuttering:
- Vertical Members (Studs): These are the vertical components that support the horizontal elements of the formwork.
- Horizontal Members (Walers): These are horizontal components that help in holding the vertical members in place.
- Sheathing: The material that forms the face of the formwork, providing the desired finish to the concrete.
- Bracing: Additional components used for stability and to resist lateral forces.
- Design and Construction Considerations:
- The design of the shuttering system depends on factors such as the load-bearing capacity required, the size and shape of the slab, and the concrete mix.
- The formwork needs to be properly aligned, leveled, and braced to ensure the slab’s structural integrity and an even surface.
- Installation Process:
- Before placing concrete, the formwork is assembled and installed according to the design specifications.
- The formwork is inspected to ensure it is properly aligned and secured.
- Concrete is then poured into the shuttering, and it takes the shape of the mold.
- Stripping the Formwork:
- After the concrete has set and gained sufficient strength, the formwork is removed. This is known as stripping.
- The timing for stripping depends on the type of concrete used, environmental conditions, and project specifications.
- Reuse of Formwork:
- Depending on the type of formwork material, it may be reusable for multiple concrete pours.
- Proper cleaning and maintenance of the formwork contribute to its longevity and reusability.
- Finishing and Curing:
- Once the formwork is removed, the slab may require additional finishing processes such as curing, which involves maintaining adequate moisture for the concrete to gain strength.
Shuttering is a critical component in the construction of slabs, influencing the quality, aesthetics, and structural integrity of the final concrete structure. Proper planning, installation, and maintenance of formwork are essential for the success of a concrete slab construction project.