this leads to a smaller deflection compared to conventional
RCC because of the higher rigidity of the un-cracked section.
Hence reduction in thickness of the slab compared to
conventional RCC is the rationale for using post-tensioning
system for spans over 10m and above. Further the lack of
cracking leads to a watertight structure. Flat plat/slab design
and build contractors in India claim a nearly 15to 20%cost
reduction. But many practical considerations have shown
that theoretical cost reduction is not possible practically
resulting in high cost of post tensioned flat slab
constructions.