Types of Formwork Shuttering for Concrete Construction
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.
Concrete Formwork can use temporary or permanent molds, which hold the poured concrete in shape until it hardens and achieves enough strength to support itself. Formwork can be classified in many ways:
- Type of material used
- By the concrete element supported
- Removable or permanent
Formwork has a fundamental role in concrete formwork. It must have enough strength to bear all the loads present during casting operations, and must then hold its shape while concrete hardens.
When selecting formwork it is important to consider the type of concrete and the pouring temperature, since both affect the pressure exerted. Also, Concrete formwork must be capable of resisting the loads of wet and dry concrete.
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.
Types of Formwork Shuttering
Steel formworks:
Steel forms are stronger, durable and have longer life than timber formwork and their reuses are more in number. Steel forms can be installed and dismantled with greater ease and speed. The quality of exposed concrete surface by using steel forms is good and such surfaces need no further treatment. Steel formwork does not absorb moisture from concrete. Steel formwork does not shrink or warp
Aluminum formworks
Often used in prefabricated formwork, that is put together on site. Aluminum is strong and light, and consequently fewer supports and ties are required. The lighter sections will deflect more, but this can be avoided by simply following the manufacturers recommendations.
Plastic formworks
Glass reinforced plastics and vacuum formed plastics are used when complicated concrete shapes are required. Although vacuum formed plastics will always need support, GRP can be fabricated with integral bearers making it self supporting. Like steel, plastic formwork can be reused many times, as long as care is taken not to scour the surface whilst vibrating the concrete.