7. PRESTRESSED CONCRETE BOX GIRDER
- Minimum ultimate compressive strength shall not less than 350 ksc. cylinder at 28 days.
- Minimum transfer strength shall not less than 245 ksc. cylinder.
- High early strength Portland cement is used and cement content shall not less than 350 kgs. per cubic metre.
- PC. 7-Wire strand Ø 3/8” , Ø1/2” (Grade 270 k) are used and minimum breaking strength is about 18,500 ksc.
- Minimum force transfer to concrete shall not be less than 70% of breaking strength.