precast technology

Precast hollow core slabs are among the most advanced products in the precast concrete industry. It has quickly become a cost-effective alternative to poured and traditional concrete methods. Portland’s hollow core panels are manufactured using the extrusion method.

The extrusion process involves feeding dry mix concrete onto rotation screws by means of a moving hopper. The screws force the concrete through shaping plates and out of the rear of the extrusion machine, while holes are forced into the concrete panels by circular mandrels, trailing behind the screws. During the process the extrusion machine is propelled by the back pressure of the concrete and together with various vibrating plates it produces the extremely well compacted concrete panel.

Read more about extrusion.

extrusion hollowcore (1024x682)

Hollow core slabs have longitudinal cores. The extrusion process causes weight saving, making the slabs up to 30% lighter than traditional concrete. It can also achieve larger spans than in-situ enforced concrete slabs of similar depth. This reduces transport costs and causes a more efficient usage of the pre-stressing cable.

The larger holes also make it easier to accommodate service pipe conduits, including down lights and transformers. The manufacturing process ensures that the undersides of the deck panels are smooth and level, eliminating the need for further skimming. This makes only a textured paint finish necessary to finish the job.

Hollow core decks require no propping, allowing full unrestricted access for finishing trades to continue work below the deck.

The Advantages

  • Internationally most widely used type precast flooring and roofing.
  • Reduced weight gives savings in foundations and other structures as well as in transport and installation.
  • Hollowcore slabs have longitudinal cores, which main purpose is to reduce the weight of the floor.
  • They are mainly used in buildings with large spans such as office buildings, hospitals, schools, shopping centers, industrial buildings etc. Another common application is apartment buildings and houses because of the favourable cost rate and fast installation time.
  • Suitable for longer and shorter spans normally 1200 mm wide with a choice of two depths:
  • 160 mm with maximum span of 6.5 m
  • 200 mm with maximum span of 8.5 m
  • Longer spans, less supports, more freedom in floor plan and design.
  • Dry installation; only the joints need to be wetted and grouted.
  • Installation faster and simpler thanks to lower weight and precise dimensions.
  • Smooth soffit requires no skimming; only a textured paint finish.
  • No propping, shuttering or site curing required.
  • No concrete topping only a light finish screed.
 
Download Portland Hollowcore info booklet