A hollow core slab (Dutch: breedplaatvloer), also known as a lattice girder slab, is a prefabricated concrete floor system consisting of thin precast slabs that serve as permanent formwork for an in-situ cast concrete topping. The precast element contains embedded lattice girders that provide stiffness during transport and construction, and bond the two concrete layers into a composite floor.
How a hollow core slab is constructed
- Prefabrication — thin concrete slabs (typically 50-80 mm thick) are cast in a factory with steel lattice girders projecting from the top surface
- Delivery and placement — the precast slabs are transported to site and lifted onto the supporting structure by crane
- Reinforcement — additional reinforcement bars are placed between and over the lattice girders to handle structural loads
- Concrete topping — fresh concrete is poured on top to a total floor thickness of 200-400 mm, depending on span and load requirements
- Curing — once the topping has cured, the floor acts as a monolithic composite slab
Advantages
- Fast construction — large panels cover floor areas quickly, reducing on-site labour
- Smooth soffit — the factory-cast underside provides a flat ceiling that can be left exposed or finished with minimal plaster
- Design flexibility — openings for stairs, shafts, and services can be planned in advance
- Structural efficiency — the composite action between precast and in-situ concrete creates a strong, stiff floor
Application
Hollow core slabs are widely used in residential, commercial, and industrial buildings. They are particularly popular in multi-storey construction where speed and a clean ceiling finish are important. Typical spans range from 5 to 12 metres depending on slab thickness and loading conditions.
Related Terms
- Reinforced concrete
- Precast concrete
- Lattice girder
- Floor slab
- Composite construction
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