why are railway track laid in large sised concrete leapers
a brief visit to wikipedia (after figuring out what your execrable spelling meant) produced:
Advantages
Do not rot like timber sleepers.
Extra weight makes track more stable, particularly with changes in temperature.
Withstand fire hazards better than wooden sleepers.
Longer life than wooden sleepers
Less maintenance means lower ongoing costs and less track closures
Pads
Concrete sleepers usually have rubber pads of about 10mm thickness between the rail and the baseplate to absorb some of the shock of the passing train.
Disadvantages
When trains derail and the wheels hit the sleepers, timber sleepers tend to absorb the blow and remain intact, while concrete sleepers tend to shatter and have to be replaced.
Concrete sleepers are heavier and need stronger people and even special tools to carry them.
Gives more retentivity to the track.
Cost more, especially initial cost.