Concrete construction: the soffit (underside) formwork of slabs may be removed only after approximately how many days under normal conditions?

Introduction / Context:
Formwork removal timing balances construction speed with safety and performance. The soffit of slabs supports self-weight and early-age loads; removing it too soon risks deflection and cracking.

Given Data / Assumptions:

• Ordinary Portland cement, typical ambient temperatures.
• Sound curing practices; props may remain per code if needed.
• Question focuses on usual benchmark times, not special concretes.

Concept / Approach:
Industry practice sets minimum periods before stripping based on member type. For slabs, side forms may go earlier, but the soffit formwork generally remains about 7 days under normal conditions to ensure adequate strength and stiffness. Beams/girders require longer or continued propping.

Step-by-Step Solution:
Identify member: slab soffit → medium stripping time.Select common benchmark: approximately 7 days.

Verification / Alternative check:
Many code tables and handbooks cite ~7 days for slab soffits at normal temperatures, with adjustments for rapid hardening cement or cold weather.

Why Other Options Are Wrong:

• 1 or 4 days: too early for most slabs; risk of deflection.
• 14 days: conservative but not typically required for slabs (more for beams/props retention).

Common Pitfalls:

• Confusing side-form removal (early) with soffit removal (later).

Final Answer:
7 days