- Hollow-core slab
A hollow core slab , also known as a voided slab ( _de. Hohlkörperplatte, _nl. Kanaalplaat or Welfsel, _sv. hålplatta, _fi. ontelolaatta) is a
prefabricated slab ofprestressed concrete typically used in the construction offloor s in multi-storyapartment building s. The slab has been especially popular in countries where the emphasis of home construction has been onaffordable housing .The
concrete slab has tubular voids extending the full length of the slab, typically with a diameter nearly equal to the thickness of the slab. This makes the slab much lighter than a massive floor of equal thickness or strength. The slabs are typically 120cm wide with standard thicknesses between 15cm and 50cm. The concreteI-beam s between the holes contain the steel rods that provide the majority of thetensile stress that hold the slabs together under heavy loads.Slabs are usually produced in lengths of about 100 meters. The process involves
extruding wet concrete along with the steel rods from a moving mold. The continuous slab is then cut according to the lengths required on theconstruction site . Factory production provides the obvious advantages of reduced time, labor and training.Hollow-core slabs are poor sound insulators. To meet modern standards of
soundproofing the floor needs to be covered with a softfloor covering that is able to dampen the sound of footsteps. An alternative is to use a thin "floating" slab of concrete insulated from the voided slabs.However, as the hollow-core slabs are mainly stationary
air inside. Thus, they are excellent thermal insulators and they require very littlebuilding insulation . This is a contributory factor especially in countries and climates where annual temperature variation can be great, such as inScandinavia .Bridges
Voided slabs are also used in the construction of
bridge s. In many cases the slab in molded "in situ ".External links
* [http://www.concreteissues.com Concrete Issues]
* [http://www.precastfountain.com Precast Fountain]
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