Precast concrete

A precast concrete or concrete element is a component of concrete, reinforced concrete or prestressed concrete, which is prefabricated in a factory industrially or on the construction site and subsequently, often mixed with a crane into its final position. Precast concrete products are widely available and come in varied designs had been used.

• 2.1 Monolithic components
• 2.2 sandwich constructions
• 2.3 spun concrete pipes
• 2.4 semi-finished parts

Use

Commercial and industrial

During the construction of commercial buildings, especially in industrial halls but also office buildings is the use of prefabricated components on the agenda.

Housing

In residential construction, precast concrete products come in erecting all blocks for use. The design was in the GDR and is widely used in many other countries. Entire neighborhoods were built with the construction methods, which are referred to the use of concrete slabs as housing estates (see also panel construction ).

In the current housing prefabricated units in Germany come ( note aerated concrete definition) especially for system wall panels, ceiling and roof panels and staircases used. Concrete stairs are rarely cast in place.

Wind turbines

Even with hybrid towers for wind turbines, which are mainly associated with widespread through large hub heights necessary there in Midland, are used in the lower part of the tower is usually precast concrete parts.

Mauerbau

Walls, especially high, for example, for containment of prisons are often constructed from concrete elements. Well-known examples are the former Berlin Wall made ​​of elements and the Israeli separation barrier around the Palestinian territories.

Civil engineering

Compared to the use of prefabricated elements in construction of ducts, for example, along railway lines and sewer lines there are few alternatives.

Composable concrete pipes of different diameter are for the construction of water and sewer pipes of all kinds are used.

With successive settable concrete manhole rings dug wells, cisterns, small wastewater treatment plants and manholes are built. Concrete manhole rings are usually produced as a standard component in accordance with DIN 4034 and have nominal diameters of 500, 1000, 1200, 1500 or 2000 mm

Pipeline

Also overhead line masts made ​​of concrete, so-called concrete poles, usually consisting of one or a plurality of prefabricated concrete elements. They are mainly for lower heights (up to 20 meters) and for voltages below 50 kV used (also as a carrier of overhead contact lines for electric railways ). Smaller transmission towers made ​​of concrete also usually consist of one or more concrete elements.

Road construction

In road construction, concrete elements come today as boundary and boundary stones, angle retaining walls, traffic islands and dividers, retaining wall, street lamps and manhole rims used. Whole walkways can be created from paving stones or concrete pavement. In the construction area are often barrier elements made ​​of concrete, so-called New Jersey elements used. Taxiways and runways can be built from prefabricated concrete slabs, usually but these are cast in place.

Bridge building

Smaller bridges for pedestrians and cyclists are often completely delivered as finished parts. However, road and railway bridges sometimes be fabricated using such components, abroad, in part as a complete finished part.

Tunneling

In tunneling, there is the so-called tubbing, in which are prefabricated tubbing used for the construction of the tunnel vault, usually where seven of these precast elements form a complete ring. For the past under the roadway plant management channels are similar components used.

Types

Monolithic components

Classic concrete and precast reinforced concrete are made of solid ( monolithic ) concrete or reinforced concrete. This is the simplest type of precast concrete elements exist in countless shapes and sizes. Examples include paving and angular stones, stair treads, special parts for the construction of platforms, columns and beams for industrial construction, as well as stairs and wall elements for the construction of residential buildings. A disadvantage of the use in building construction, that such elements only consuming can be connected to each other. The possibilities of connection are limited primarily to Vergusstaschen with connection reinforcement or special mounting parts that are filled on site with concrete and connect the part so permanently to the subsequent component, and Weld steel in the concrete already in the right place in the finished part are inserted and welded to the connecting steel components at the construction site. In this technique, a large part of the Eastern European prefabricated housing was built.

One way to create exactly matching finished parts for the bridge is the contact method (also called match casting ). Because a part is used as formwork for the next part, the parts fit each other very closely later. The finished parts can be biased then even with a "dry joint ", ie without adhesive or mortar.

Sandwich constructions

In order to achieve better thermal insulation values ​​, precast concrete wall panels can also run multiple layers, with the outer sides are made of reinforced concrete and the gap with insulation (usually EPS / polystyrene foam) filled. The outer shells are connected through the insulation material with metal anchors.

Spun concrete pipes

Hollow parts such as pipes and poles are produced as spun concrete in a rotating mold, in which the centrifugal force pushes the concrete on the outer wall and such a mold can be produced.

Semi-finished products

Because of their efficiency, even reinforced concrete semi-finished parts are used in order to dispense with the time-consuming manufacturing a formwork locally. By now, most reinforced concrete slabs instead of hollow core slabs are manufactured as semi- precast slab elements in Germany. Similarly, the walls can be made from semi-finished parts. You will then be referred to as hollow walls or triple walls as element walls are in contrast to the ceiling element factory from two connected by steel girder shells between the on site only concrete is poured.