According to IS 456:2000, what is the slump for medium degree of workability in heavily reinforced sections like slabs, beams, walls, columns?
Correct Answer: D. 50 – 100 mm
📚 Detailed Explanation: IS 456 Slump for Heavily Reinforced Sections
Heavily reinforced sections require higher workability than plain concrete elements because the concrete must flow around closely spaced rebars without leaving voids. IS 456:2000 Table 2 specifies appropriate slump ranges.
Why D (50–100 mm) is correct: For slabs, beams, walls, and columns placed without pumping, IS 456 specifies medium workability with slump 50–100 mm. This range ensures: (1) concrete flows between rebars; (2) vibration effectively consolidates the mix; (3) adequate paste for rebar bond. Options A (10–25 mm) and B (25–50 mm) are too stiff for reinforced sections. Option C (0–10 mm) is for no-slump / VB test range concrete.
IS 456:2000 — Slump for Different Elements
| Type of Construction | Degree of Workability | Slump (mm) |
|---|---|---|
| Blinding concrete, mass foundations | Very low | 0–25 |
| Lightly reinforced foundations | Low | 25–75 |
| Beams, slabs, walls, columns (normal RCC) | Medium | 50–100 |
| Thin sections, pumped concrete | High | 100–150 |
- Heavily reinforced sections require 50–100 mm slump to ensure concrete reaches all parts of the formwork.
- Pumped concrete in the same sections requires higher slump: 100–150 mm (Q16).