Modular steel frame formwork for a foundation.

Timber formwork for a concrete column.

Sketch of the side view of traditional timber formwork used to form a flight of stairs.

Pose of one formwork.

Formwork is the term given to either temporary or permanent moulds into which concrete or similar materials are poured. In the context of concrete construction, the falsework supports the shuttering moulds. Image File history File linksMetadata Download high resolution version (2592x1944, 570 KB) Summary formwork of a pile cap picture taken by störfix, 2005-09-04 Stahlrahmenschalung als Pfeilerkopfschlaung Licensing File links The following pages link to this file: Formwork Metadata This file contains additional information, probably added from the... Image File history File linksMetadata Download high resolution version (2592x1944, 570 KB) Summary formwork of a pile cap picture taken by störfix, 2005-09-04 Stahlrahmenschalung als Pfeilerkopfschlaung Licensing File links The following pages link to this file: Formwork Metadata This file contains additional information, probably added from the... Image File history File linksMetadata Size of this preview: 450 × 600 pixelsFull resolution (900 × 1200 pixel, file size: 960 KB, MIME type: image/jpeg)Photograph by Bill Bradley. ... Image File history File linksMetadata Size of this preview: 450 × 600 pixelsFull resolution (900 × 1200 pixel, file size: 960 KB, MIME type: image/jpeg)Photograph by Bill Bradley. ... For other uses, see Column (disambiguation). ... Image File history File links Size of this preview: 800 × 324 pixelsFull resolution (1086 × 440 pixel, file size: 11 KB, MIME type: image/gif) Sketch by Bill Bradley billbeee 20:40, 28 February 2007 (UTC) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev... Image File history File links Size of this preview: 800 × 324 pixelsFull resolution (1086 × 440 pixel, file size: 11 KB, MIME type: image/gif) Sketch by Bill Bradley billbeee 20:40, 28 February 2007 (UTC) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev... One half of a bronze mold for casting a socketed spear head dated to the period 1400-1000 BC. There are no known parallels for this mold. ... This article is about the construction material. ... Falseworks are temporary structures used in the building of bridges and other arched structures in order to hold the item in place until its building is sufficiently far advanced to support itself. ...

Formwork types

Formwork comes in three main types:

• Traditional timber formwork. The formwork is built on site out of timber and plywood or moisture-resistant particleboard. It is easy to produce but time-consuming for larger structures, and the plywood facing has a relatively short lifespan. It is still used extensively where the labour costs are lower than the costs for procuring re-usable formwork. It is also the most flexible type of formwork, so even where other systems are in use, complicated sections may use it.
• Engineered Formwork systems. This formwork is built out of prefabricated modules with a metal frame (usually steel) and covered on the application (concrete) side with material having the wanted surface structure (steel, timber, etc.). The two major advantages of formwork systems, compared to traditional timber formwork, are speed of construction (modular systems clip or screw together quickly) and lower life-cycle costs (barring major force, the frame is almost indestructible, while the covering may have to be replaced after a few - or a few dozen - uses, depending on the applications).
  • Re-usable plastic formwork. These interlocking and modular systems are used to build widely variable, but relatively simple, concrete structures. The panels are lightweight and very robust. They are especially suited for low-cost, mass housing schemes moladi.
• Stay-In-Place Formwork systems. This formwork is assembled on site, usually out of prefabricated insulating concrete forms. The formwork stays in place (or is simply covered with earth in case of buried structures) after the concrete has cured, and may provide thermal and acoustic insulation, space to run utilities within, or backing for finishes.
  • Stay-In-Place Structural Formwork systems. This formwork is assembled on site, usually out of prefabricated fibre-reinforced plastic forms. These are in the shape of hollow tubes, and are usually used for columns and piers. The formwork stays in place after the concrete has cured and acts as axial and shear reinforcement, as well as serving to confine the concrete and prevent against environmental effects, such as corrosion and freeze-thaw cycles.

Timber in storage for later processing at a sawmill Timber is a term used to describe wood, either standing or that has been processed for use—from the time trees are felled, to its end product as a material suitable for industrial use—as structural material for construction or wood... Towers of Hanoi constructed from plywood. ... Particle board is a material manufactured from wood particles (e. ... Moladi is a South African construction company specialising in technology for producing low cost housing, mainly intended for third world countries, by a patented process of reusable plastic formwork. ... Insulating Concrete Forms or Insulated Concrete Forms (ICF or ICFs) are stay-in-place formwork for energy-efficient, cast-in-place reinforced-concrete walls. ... Fibre-reinforced plastic (FRP) (also Fibre-reinforced polymer) is a composite material comprising a polymer matrix reinforced with fibres. ... Shear stress is a stress state where the stress is parallel or tangential to a face of the material, as opposed to normal stress when the stress is perpendicular to the face. ... For the hazard, see corrosive. ...

Slab Formwork

History

Pantheon dome

Schematic sketch of traditional formwork

Some of the earliest examples of concrete slabs were built by Roman engineers. Because concrete cannot resist tension or torsional stress, these early structures consisted of arches, vaults and domes. The most notable concrete structure from this period is the Pantheon in Rome. To mold these structure, temporary scaffolding and formwork or falsework was built in the future shape of the structure. These building techniques were not isolated to pouring concrete, but were and are widely used in Masonry. Because of the complexity and the limited production capacity of the building material, concrete’s rise as a favored building material did not occur until the invention of Portland cement and reinforced concrete. Image File history File linksMetadata Download high-resolution version (1536x2048, 668 KB) Oculus, Pantheon, Rome. ... Image File history File linksMetadata Download high-resolution version (1536x2048, 668 KB) Oculus, Pantheon, Rome. ... Facade of the Pantheon The Pantheon (Latin Pantheon[1], from Greek Πάνθεον Pantheon, meaning Temple of all the gods) is a building in Rome which was originally built as a temple to the seven deities of the seven planets in the state religion of Ancient Rome. ... Tensile stress (or tension) is the stress state leading to expansion; that is, the length of a material tends to increase in the tensile direction. ... // Mathmatics In mathematics, the term torsion has several meanings, mostly unrelated to each other. ... In the ancient Greek philosophy, arche (ἀρχή) is the beginning or the first principle of the world. ... The Lierne vault of the Liebfrauenkirche, Mühlacker 1482. ... For other uses, see Dome (disambiguation). ... Facade of the Pantheon The Pantheon (Latin Pantheon[1], from Greek Πάνθεον Pantheon, meaning Temple of all the gods) is a building in Rome which was originally built as a temple to the seven deities of the seven planets in the state religion of Ancient Rome. ... Falseworks are temporary structures used in the building of bridges and other arched structures in order to hold the item in place until its building is sufficiently far advanced to support itself. ... This article refers to the building structure component; for the fraternal organization, see Freemasonry. ... Sampling fast set Portland cement Portland cement is the most common type of cement in general usage, as it is a basic ingredient of concrete, mortar and plaster. ... Reinforced concrete at Sainte Jeanne dArc Church (Nice, France): architect Jacques Dror, 1926–1933 Reinforced concrete, also called ferroconcrete in some countries, is concrete in which reinforcement bars (rebars) or fibers have been incorporated to strengthen a material that would otherwise be brittle. ...

Traditional Slab Formwork

Traditional timber formwork on a jetty in Bangkok.

On the dawn of the rival of concrete in slab structures, building techniques for the temporary structures were derived again from masonry and 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 meters apart, depending on thickness of slab. Between these stringers, joists are positioned roughly 12 inches, 30 centimeters apart upon which boards or plywood is 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 21 millimeters. Image File history File links Size of this preview: 799 × 600 pixelsFull resolution (1284 × 964 pixel, file size: 442 KB, MIME type: image/jpeg)Photograph by Bill Bradley. ... Image File history File links Size of this preview: 799 × 600 pixelsFull resolution (1284 × 964 pixel, file size: 442 KB, MIME type: image/jpeg)Photograph by Bill Bradley. ... Location within in Thailand Coordinates: , Country Settled Ayutthaya Period Founded as capital 21 April 1782 Government  - Type Special administrative area  - Governor Apirak Kosayothin Area  - City 1,568. ... Towers of Hanoi constructed from plywood. ...

Timber Beam Slab Formwork

Similar to the traditional method, but stringers and joist are replaced with engineered wood beams and supports are replaced with metal props. This makes this method more systematic and reusable.

Metal Beam Slab Formwork

Similar to the traditional method, but stringers and joist are replaced with aluminium or steel beams and supports are replaced with metal props. This also makes this method more systematic and reusable. to be completed. Metal Beam Slab Formwork also makes a smoother finish and is easier to remove when cement has cured.

Modular Slab Formwork

Panelized ceiling slab forming system with temporary support structures on a university dorm project.

With preassembled timber modules or steel or aluminium modules. to be completed Image File history File linksMetadata Download high-resolution version (1500x1812, 3999 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Falsework Formwork PERI GmbH Metadata This file contains additional information, probably added from the digital camera or scanner... Image File history File linksMetadata Download high-resolution version (1500x1812, 3999 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Falsework Formwork PERI GmbH Metadata This file contains additional information, probably added from the digital camera or scanner...

Table or Flying Form Systems

United States Patent 4036466.

These systems consist of slab formwork “tables” that are reused on multiple stories of a building without being dismantled. The assembled sections are either lifted per elevator or “flown” by crane from one story to the next. Once in position the gabs between the tables or table and wall are filled with “fillers”. They vary in shape and size as well as their building material. The use of these systems can greatly reduce the time and manual labor involved in setting and striking the formwork. Their advantages are best utilized by large area and simple structures. It is also common for architects and engineers to design building around one of these systems.

Structure

Flying formwork tables with aluminium and timber joists. The tables are supported by shoes attached to previously poured columns and walls

A table is built much the same way as a beam formwork but the single parts of this system are connected together in such a way making them transportable. The most common sheathing is plywood, but steel and fiberglass are also in use. The joist are either made from timber, wood I-beams, aluminium or steel. The Stringers are sometimes made of wood I-beams but usually from steel channels. These are fastened together (screws, weld or bolted) to become a “deck”. These decks are usually rectangular but can also be other shapes.

Support

All support systems have to be height adjustable to allow the formwork to be placed at the correct height and to be removed after the concrete is cured. Normally adjustable metal props similar to (or the same as) those used by beam slab formwork are used to support these systems. Some systems combine stringers and supports into steel or aluminium trusses. Yet other systems use metal frame shoring towers, which the decks are attached to. Another common method is to attach the formwork decks to previously cast walls or columns, thus eradicating the use of vertical props altogether. In this method, adjustable support shoes are bolted through holes (sometimes tie holes) or attached to cast anchors.

Size

The size of these tables can vary from 70 sqft. to 1500 sqft. or 8m² to 150m². There are two general approaches in this system.

Crane handled

This approach consists of assembling or producing the tables with a large formwork area that can only be moved up a level by crane. Typical widths can be 15, 18 or 20ft. or 5 to 7 meters but their width can be limited, so that it is possible to transport them assembled, without having to pay for an oversize load. The length vary and can be up to 100ft. (or more) depending on the crane capacity. After the concrete is cured, the decks are lowered and moved with rollers or trolleys to the edge of the building. From then on the protruding side of the table is lifted by crane whiles the rest of the table is rolled out of the building. After the center of gravity is outside of the building the table reattached to another crane and flown to the next level or position. This technique is fairly common in the United States and east Asian countries. The advantages of this approach are the further reduction of manual labor time and cost per sqft. or m² of slab and a simple and systematic building technique. The disadvantages of this approach are the necessary high lifting capacity of building site cranes, additional expensive crane time, higher material costs and little flexibility.

crane fork or elevator handled

Formwork tables in use at a building site with more complicated structural features

By this approach the tables are limited in size and weight. Typical widths are between 6 to 10ft. or 2 to 3 meters, typical lengths are between 12 and 20ft. or 4 to 7 meters, though table sizes may vary in size and form. The major distinction of this approach is that the tables are lifted either with a crane transport fork or by material platform elevators attached to the side of the building. They are usually transported horizontally to the elevator or crane lifting platform single handedly with shifting trolleys depending on their size and construction. Final positioning adjustments can be made by trolley. This technique enjoys popularity in the US, Europe and generally in high labor cost countries. The advantages of this approach in comparison to beam formwork or modular formwork is a further reduction of labor time and cost. Smaller tables are generally easier to customize around geometrically complicated buildings (round or non rectangular) or to form around columns in comparison to their large counterparts. The disadvantages of this approach are the higher material costs and increased crane time (if lifted with crane fork).

Cassette Formwork

to be completed. see structural Coffer Coffering on the ceiling of the Pantheon, Rome In architecture, a coffer is (plural: coffering) is a sunken panel in the shape of a square or octagon that serves as a decorative device, usually in a ceiling. ...

Usage

For removable forms, once the concrete has been poured into formwork and has set (or cured), the formwork is struck or stripped (removed) to expose the finished concrete. The time between pouring and formwork stripping depends on the job specifications, the cure required, and whether the form is supporting any weight, but is usually at least 24 hours after the pour is completed. For example, the California Department of Transportation requires the forms to be in place for 1-7 days after pouring,^[1] while the Washington State Department of Transportation requires the forms to stay in place for 3 days with a damp blanket on the outside^[2].

Spectacular accidents have occurred when the forms were either removed too soon or had been under-designed to carry the load imposed by the weight of the uncured concrete. Less critical and much more common (though no less embarrassing and often costly) are those cases in which underdesigned formwork bends or breaks during the filling process (especially if filled with a high-pressure concrete pump). This then results in fresh concrete escaping out of the formwork in a form blowout, often in large quantities.

Concrete exerts less pressure against the forms as it hardens, so forms are usually designed to withstand a number of feet per hour of pour rate to give the concrete at the bottom time to firm up. For example, wall or column forms are commonly designed for a pour rate between 4-8 ft/hr.^{[citation needed]} The hardening is an asymptotic process, meaning that most of the final strength will be achieved after a relatively short time, though some further hardening can occur depending on the cement type and admixtures. In mathematics and applications, particularly the analysis of algorithms, asymptotic analysis is a method of classifying limiting behaviour, by concentrating on some trend. ...

Wet concrete also applies hydrostatic pressure to formwork. The pressure at the bottom of the form is therefore greater than at the top. In the illustration of the column formwork to the right, the 'column clamps' are closer together at the bottom. Note that the column is braced with steel adjustable 'formwork props' and uses 20 mm 'through bolts' to further support the long side of the column. Fluid pressure is the pressure on an object submerged in a fluid, such as water. ...

References

Caltrans logo The soaring ramps in the stack interchanges favored by Caltrans often provide stunning views. ... The Washington State Department of Transportation, or WSDOT, led by a Secretary and overseen by the Governor, is a Washington governmental agency that constructs, maintains, and regulates the use of the states transportation infrastructure. ...

See also

Terminology

• Climbing formwork (formwork that climbs up the rising building during the construction)
• Concrete cover (depth of the concrete between reinforcing steel and outer surface)
• Falsework

Climbing formwork on a skyscraper in New Zealand - the whole white upperstructure is actually formwork and associated facilities. ... Concrete cover is the region between the exposed concrete surface and the nearest surface of the reinforcing bar, in reinforced concrete members. ... Falseworks are temporary structures used in the building of bridges and other arched structures in order to hold the item in place until its building is sufficiently far advanced to support itself. ...

External links

• DESTIL Formwork Guide and typologies for the use of formwork