Prestressed concrete demands better materials than RCC: a higher minimum concrete grade (commonly M40 for pre-tensioned, M30+ for post-tensioned — confirm against the current edition) for the high transfer stresses and low creep, and high-tensile prestressing steel — 7-ply strand (IS 14268), hard-drawn wire (IS 1785), or indented wire (IS 6003) — verified by test, never coil-tag, and protected absolutely from nicks/corrosion.
Key Requirements
•Minimum concrete grade higher than RCC (e.g. ~M40 pre-tension / ~M30+ post-tension — verify current edition)
•Prestressing steel: low-relaxation strand (IS 14268) / wire (IS 1785) / indented wire (IS 6003) of the specified class
•Steel sampled & tested per IS 10790 Part 1 — never coil-tag acceptance
•Protect tendons from nicks/corrosion (notch-sensitive at working stress) and use the design relaxation class
•Construction (stressing, elongation reconciliation, grouting) per IS 8543 for bonded post-tensioning
Practical Notes
✓Higher concrete grade is not optional — transfer stresses and creep-sensitivity demand it; using RCC-grade concrete is a common, serious error.
✓Prestressing steel is the one material where coil-tag acceptance is unacceptable — test per IS 10790 Part 1 and protect it absolutely.
Common Mistakes
⚠Using RCC-grade concrete instead of the higher prestressed minimum.
⚠Coil-tag acceptance of prestressing steel (no IS 10790 Part 1 testing).
⚠Wrong relaxation class / nicked or corroded tendons.