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Formwork is an essential part of concrete construction as it provides the mould in which an element is cast. Owing to the relatively high cost of formwork, it is standard practice to maximise re-use. Formwork type will affect the potential for re-use. Metal forms made from recycled steel, for example, may be used hundreds of times.
In comparison, plywood may be cheap to buy, but can only be used as quality formwork a few times. However, all formwork can be recycled or used for secondary purposes. The environmental benefits of permanent formwork, which remains in place after concrete casting and can improve thermal insulation, should be considered as part of a concrete system.
The type of timber and whether it is from a managed forest and sustainable resource are also important environmental considerations. Modern formwork systems are extremely efficient, and the impact of formwork on the environment is small compared with that of concrete. .
For an element 250 mm thick, the formwork adds 4.5% to the total impact of concrete on the environment. Increasing the section size reduces this value as less formwork is used, e.g. 2.4% and 1.1% for section thicknesses of 500 mm and 1000 mm respectively. With good site practice, there is little scope for reducing this furtherFor further information see Concrete and the Environment, published in CONCRETE in September 2001, pp39–46. Copies are available as a free download from the Members Area of the Concrete Society web site.
Acknowledgement: The Concrete Society