Formwork Removal – slab (hall) of about 4 m × 5 m plan For a reinforced concrete hall slab spanning about 5 m in one direction (4 m × 5 m room), after how many days are the soffit props typically removed under normal conditions, as per conventional guidance?

Introduction / Context:
Safe removal of formwork and props depends on member type, span, loading, and concrete strength development. Codes and handbooks provide minimum periods for stripping and propping to avoid excessive deflection or damage when the concrete is still green.

Given Data / Assumptions:

• RC slab over a hall of plan 4 m × 5 m; controlling span ≈ 5 m.
• Normal temperatures and adequate curing.
• No accelerating admixtures or special early-strength concrete assumed.

Concept / Approach:

Conventional guidance (widely taught for IS practice) suggests: vertical sides of beams/walls ≈ 1–2 days; props to slabs up to about 4.5 m span ≈ 7 days; props to slabs over about 4.5 m span ≈ 14 days; props to beams/arches often require longer. For a 5 m span slab, the appropriate category is “over 4.5 m,” so 14 days is selected.

Step-by-Step Solution:

Verification / Alternative check:

Field practice retains props longer in cold weather or where early loading is expected. In accelerated curing or with high early strength mixes, periods may be reduced subject to strength checks.

Why Other Options Are Wrong:

5–10 days are suitable for shorter spans; 21 days is conservative beyond common guidance for slabs of this span under normal conditions.

Common Pitfalls:

Removing props without verifying strength; ignoring temperature effects; placing construction loads prematurely on green slabs.

Final Answer:

14 days