Special Formwork
Introduction
A formwork is the system of temporary or permanent molds that are used to shape concrete or other similar materials such as rammed earth before setting.[1].
formwork slab
History
Roman architects built the first mass concrete structures. As mass concrete cannot absorb large tensile and torsional forces, these first structures were arches "Arch (construction)"), vaults and domes, which function only in compression. The most notable concrete structure of this stage is the dome of the Pantheon in Rome. The formwork was made with temporary scaffolding and formwork in the shape of the future structure. These auxiliary construction elements are not only used to pour concrete, they have also been and are widely used in other masonry work. For concrete, the Romans used gypsum and lime as binders, in addition to a natural cement obtained from the Pozzuoli stone, called pozzolana, but it is not an easy mineral to obtain in other places, so concrete was not used again as a construction material, until the invention of Portland cement; Reinforced concrete could not be made with other binders since they attack the iron of the reinforcement, oxidizing it.
Traditional formwork slab
When the first concrete slab structures emerged, techniques that came from masonry and carpentry were used to construct temporary structures. The traditional slab formwork technique consists of wooden supports (trunks of young trees), arranged in rows, one to two meters apart, depending on the thickness of the slab, that support the formwork elements. Between these elements, the sopandas, like beams, are placed approximately every thirty cm, along with overlapping plywood. These wooden beams (sopandas) are usually five to ten cm wide and about fifteen high.
metal formwork slab
Similar to the previous one, but replacing the auxiliary beams (sopandas) with other metal ones, made of aluminum or steel. The "struts" are also usually metal, and can be reused.