Formwork History-1
Timber beam slab formwork
Similar to the traditional method, but http://en.wikipedia.org/w/index.php?title=Stringer_(woodworking)&action=edit&redlink=1 and joist are replaced withhttp://en.wikipedia.org/wiki/Engineered_wood beams and supports are replaced with metal props. This makes this method more systematic and reusable.
Traditional slab formwork
On the dawn of the rival of concrete in slab structures, building techniques for the temporary structures were derived again from http://en.wikipedia.org/wiki/Masonry and http://en.wikipedia.org/wiki/Carpentry. The traditional slab formwork technique consists of supports out of lumber or young tree trunks, that support rows of stringers assembled roughly 3 to 6 feet or 1 to 2 metres apart, depending on thickness of slab. Between these stringers, joists are positioned roughly 12 inches, 30 centimeters apart upon which boards or http://en.wikipedia.org/wiki/Plywood are placed. The stringers and joists are usually 4 by 4 inch or 4 by 6 inch lumber. The most common imperial plywood thickness is ¾ inch and the most common metric thickness is 18 mm.
All of these are from website.