In a simply supported RCC slab, the upper part of the slab is subjected to compressive forces while the lower portion is subjected to tensile forces. Concrete is very good in compression while it is weak in tension. Hence the steel reinforcement is placed in the tension zone. The concrete in this portion is only for holding together the steel reinforcement and has no structural purpose. This ‘un-productive’ concrete can be replaced by a ‘Filler’ material which will reduce the weight of the slab and also reduce the cost by reducing the amount of concrete used. Also, since the weight of the slab is thus reduced, lesser steel is also required for reinforcement, further reducing the cost.There is no reductoin in the structural strength of the slab at all and it will act as a normal load bearing slab.Common filler materials are light weight materials like Mangalore tiles, clay pans, bricks, waste bottles, coconut shells, thermocol etc. Reduces the cost of the slab by around 25-30% Creates interesting designs and patterns on the ceilingHelps in better thermal insulation of the slab due to the air pockets present. Reduces the load on the foundation