Precast Floor

Hollow Core slab

The hollowcore slab is a precast prestressed concrete element extensively used as a flooring system. Mega Prefab’s hollow core slabs (or dalle alvéolée in french) are produced at high volume at our factory in Lebanon. We offer slabs depths ranging from 150 to 400 mm, for spans of 4 to 15 meters, live loads from 0.2 to 8 Tons/m2, and fire resistance up to 4 hours.

The slab’s success is owing to the combination of high efficiency of design, automated production technology resulting in remarkable low price, fair face concrete soffit as well as its high quality concrete and durability. The automated manufacturing process uses a combination of dry mix concrete and shear compaction, which considerably reduces the consumption of water if compared to the conventional process.The hollow core slab is manufactured using long line extruders which form continuous cores running through the slabs. The primary purpose of these cores is to decrease by 40% to 50% the weight of the slabs, which leads to significant savings in the rest of the members in the building construction. They are also used as preexisting conduits in which to place electrical cables and pipes, thus reducing even further the overall construction time.


The hollow core slab can be used with a structural topping cast on top and will works as a composite section at service stage; its top is cleaned and roughened to
insure the bonding between the two concrete layers. During erection the slab is not propped and is designed as a simply supported slab. It is reinforced with T12.5mm, T9.3mm or 5 mm prestressed strands having strength of 1860 Mpa, those strands will protrude outside the slab’s edge and into the support to anchor for shear. The Hollow core slab has a concrete strength of 450 kg/ cm2 at 28 days. 

Product use

All building types (commercial & industrial structures, hotels, schools, shopping centers) except upper residential floors. Hollow core slabs are rarely used in residential apartments as the column grid is usually non uniform. However their use in residential buildings’ parking floors gives a fair face finish, and allows large
spaces to fit three cars between columns.


  • Remarkably lower price, compared to traditional
  • Speed and ease of construction. 400m2 of installation
    per day per crane.
  • Fair face finishing.
  • No need for propping and scaffolding.
  • High strength, lightweight, durable structure.
  • Longer span and greater loads than conventional
    slabs of the same thickness.
  • Superior fire resistance.
  • Preexisting longitudinal holes that can be used as
  • Automated production under strict Quality and Safety
  • High thermal insulation properties.