Hollow core slabs are precast, prestressed concrete elements that are generally used for flooring. Some of their advantages are as follows: long spans, no propping; flexible in design; fast construction; light weight structures.
The slabs have longitudinal cores running through them, the primary purpose of the cores being to decrease the weight, and material within the floor, yet maintain maximal strength. To further increase the strength, the slabs are reinforced with steel strand, running longitudinally.
In the industry of prestressed structures, hollow core slabs represent the most advanced product. It is a constructive element whose production is highly industrialized and completely automated with the latest world’s technology. This mode of prefabricated constructive element enables economically fast and safe construction of all types of buildings.
In the last 20 years, hollow core slabs are used in construction for all types of buildings: individual and public housing facilities, schools, hospitals, factories, business centers, sacral facilities, retail centers, warehouse facilities, etc. In Sweden and Benelux countries these slabs are used in more than 50 % of ceiling structures.
Currently we offer a range of five slab depths: 200, 250, 300, 350 and 400 mm slabs, for computed spans from 4 to 16 mm and live loads from 2 to 20 KN/m2, and two levels fire resistance REI 90 and REI 120 minutes. Depending on the project requirements, in particular span and loading performance, a particular slab depth is chosen. Such variety fulfills the needs of the clients.
The hollow core slabs are lighter than custom prestressed slabs from 37 to 54 %. Thus, the cost of construction is lower, and pillars and beams are having less load. Also, we have smaller dimensions for bearing constructions and for foundations.
Hollow core slabs can bridge the spans of 16 m without support, and as a result it lowers the number of supports. These slabs transfer the load in one direction.
ADAPTIVE FOR ANY SYSTEM OF CONSTRUCTION:
These slabs are not only used in prestressed concrete structures but in masonry and steel structures, regardless of whether it is prefabrication or traditional construction.
Application of hollow core slabs saves up to 50 % of concrete and 50 % of armature, all compared to traditional slabs. It means that in structures of 1000 m2 35 tons of concrete and 7,5 tons of armature is saved.
Using the same amount of materials, workforce and energy, you can produce 1 m2 of traditional slabs and 2,5 m2 of hollow core slabs. Production of hollow core slabs is completely automated.
In 24 hours we are producing around 500 m2 of hollow core slabs.
Hollow core slabs can hold up to 2000 kg/ m2, typical for production plants and warehouses.
Production is highly equipped with machinery and performed in strictly controlled conditions.
These slabs are produced with gliders on 150 m tracks by method of concrete extrusion of high strength. Steel used is of highest quality, it is steel for prestressing Y1860S – 7, 3.7 times stronger than custom ribbed steel. Core (for hollows) is formed by pipes and concrete is mechanically solidified around them. After the concrete is solidified (for 24 hours we obtain MB 40, and for 28 days we obtain MB 60) slabs are carved for desired dimensions, stored and transported.
This system of production enables strict control of production processes and products.
Hollows can be used for various installations (heating, air conditioning, electrical installations, etc.).
Hollow core slabs are immune on fire with two levels of fire resistance REI 90 and REI 120 minutes.
FLEXIBILITY IN DESIGN:
Hollow core slabs can be produced in various dimensions and carved under different angles in shape of rhombus, which gives the ability to the designers to create curved layout solutions.
In regard to the sound insulation, hollow core slabs matching even the most rigorous standards, and are convenient for all types of buildings - especially for housing facilities.
Since they are smooth, these slabs do not need formation of descending ceilings.
SHORT PERIOD OF TIME FOR CONSTRUCTION:
Production and transport of hollow core slabs is fast and easy. In addition, because of decreased weight and appropriate dimensions slabs can be assembled directly from delivery vehicle, whereby reducing the effort and the time of assemblage. Prefabrication is lowering the costs of expensive and complicated sheaths, and assembled slabs are used as a platform for works. Well established team of assemblers in one day can assemble up to 500 m2 of these slabs.