Concrete workability guideline: what slump range (in mm) is typically recommended for placing reinforced concrete in beams and slabs?

Introduction / Context:
Slump is a quick measure of concrete workability. For beams and slabs, adequate workability eases placement and compaction without segregation, ensuring cover and finish quality.

Given Data / Assumptions:

• Normal reinforced concrete using conventional vibration.
• Ambient conditions are typical; no special admixtures like SCC assumed.
• Recommended slump ranges are those widely used in site practice and teaching references.

Concept / Approach:
Beams and slabs generally require medium workability. A slump of about 25–75 mm is commonly recommended for reinforced sections placed with needle vibrators. Higher slumps may be used with plasticizers but risk segregation if not controlled; very low slumps hamper compaction around reinforcement.

Step-by-Step Solution:
Identify member type: beams and slabs → medium workability.Select standard range → 25 to 75 mm.

Verification / Alternative check:
Site method statements and handbooks list 25–75 mm for RCC beams/slabs, 75–100 mm for columns/walls where flow around congested bars is needed.

Why Other Options Are Wrong:

• 25–50 mm: on the leaner side; may be acceptable but lower bound of common practice.
• 50–100 mm or 30–125 mm: higher workability ranges more typical for heavily reinforced members or with admixtures; not the standard teaching answer.
• None of these: incorrect because 25–75 mm is appropriate.

Common Pitfalls:

• Using high slump without admixtures, leading to segregation and bleeding.

Final Answer:
25 to 75 mm