What is formwork?
Traditionally formwork uses timber, steel and fibre glass reinforced plastics to create the mould for concrete to be poured into and formed. In modern construction, highly densified plywood is increasingly used because it is dimensionally strong but lighter, cheaper to produce and easier to install than the alternatives.
Plywood shuttering must have minimal shrinkage and be strong enough to withstand both dead and live loads of the concrete the mould is designed to contain. The plywood boards used for concrete moulds are held together by additional timber and metal supports. Once the concrete is poured and formed the formwork is pulled away.
To achieve high quality concrete works, the timber products used for the mould must be able to withstand elements as well as the concrete’s moisture and alkaline nature. Although plywood has a degree of weather resistance, to ensure the boards do not warp, rot or even split, they should be comprehensively weatherproofed. This extends their design life, making it possible for the plywood shuttering to be stored and reused for future formworks.
The surface of the shuttering boards should be as smooth as possible, making it easy to pull them off and ensuring the finishing surface of the concrete is smooth. To create the required smoothness overlays must mask the roughness of the board as much as possible.
