Hollowcore ribbed slabs derive their name from the voids or cores which run through the units. The cores can function as service ducts and significantly reduce the self-weight of the slabs, maximising structural efficiency. The cores also have a benefit in sustainability terms in reducing the volume of material used. Units are generally available in standard 1200 mm widths and in depths from 110mm to 400 mm. There is total freedom in length of units. This kind of slab is used where the construction has to be done fast. These kind of slabs are Pre cast slabs which are readymade.  The hollowcore ribbed slabs have between four and six 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 12mm diameter steel strand, running longitudinally. This is a one of the types of concrete slabs.

By using tower cranes Hollow slabs are inserted between the beams. The gaps between the slab is filled with screed.

Screed is a concrete material generally we use 20mm aggrgegate in concrete whereas in screed we use baby chips(small broken stones) as aggregates.

Hollow core ribbed slabs have excellent span capabilities, achieving a capacity of 2.5 kN/m2 over a 16m span. The long-span capability is ideal for offices, retail or car park developments. Units are installed with or without a structural screed, depending on requirements. Slabs arrive on-site with a smooth pre-finished soffit. In car parks and other open structures, pre-finished soffits offer a maintenance free solution.

Advantages:

Using hollow core ribbed slab not only reduces building costs it also reduce the overall weight of the structure.
Excellent fire resistance and sound insulation is the another attributes of hollow core slab due to its thickness.
It eliminates the need to drill in slabs for electrical and plumbing units.
Easy to install and requires less labor.
Fast in construction
No additional formwork or any special construction machinery is required for reinforcing the hollow block masonry.
Disadvantages:

If not properly handled, the hollow core ribbed slab units may be damaged during transport.
It becomes difficult to produce satisfactory connections between the precast members.
It is necessary to arrange for special equipment for lifting and moving of the precast units.
Not economic for small spans.
Difficult to repair and strengthen