Formwork – Time for Removal of Props (RCC) Choose the correct schedule for removal of props under slabs and beams, assuming ordinary Portland cement and normal ambient conditions.

Introduction / Context:
Formwork striking and removal of props must balance safety and construction speed. Removing props too early can cause excessive deflection or cracking; too late delays cycle times and increases cost.

Given Data / Assumptions:

• Cement type: ordinary Portland cement.
• Normal ambient temperature and curing conditions.
• Members: slabs and beams with specified span ranges.

Concept / Approach:

Codes provide minimum periods for removal of props based on member type and span. Beams require longer support due to higher flexural stiffness demands and slower stiffness gain compared to slabs.

Step-by-Step Solution:

Verification / Alternative check:

Project specifications may modify times based on cement type, admixtures, or accelerated curing. However, the listed figures represent widely taught baseline values.

Why Other Options Are Wrong:

• Options a to d are individually correct but partial.
• Only option e consolidates the full correct schedule.

Common Pitfalls:

Ignoring temperature effects and high early strength cements, which can shorten times, or cold weather that requires longer durations.

Final Answer:

All the above