What is column casting and What are the Steps involved in column casting? | Q & A

Column casting is the process of placing concrete into column formwork (shuttering) containing reinforcement bars, to form a vertical load-bearing RCC member that transfers loads from beams and slabs to the foundation.

Steps Involved in Column Casting (Site Practice)

Below is the standard, interview-ready sequence followed on construction sites.

1. Setting Out & Alignment

• Column center lines marked as per drawings

• Check location, size, and orientation

• Ensure correct grid position

Wrong alignment = permanent structural issue.

2. Reinforcement Fixing

• Place vertical bars as per drawing

• Provide:

  • Correct bar diameter and quantity

  • Lap length at proper location

  • Stirrups/ties at specified spacing

• Fix cover blocks (usually 25–40 mm)

3. Plumb & Level Check of Reinforcement

• Reinforcement cage checked for:

  • Verticality (plumb)

  • Proper anchorage into footing

• Tie bars firmly to avoid movement

4. Shuttering / Formwork Fixing

• Fix column shuttering tightly

• Ensure:

  • Proper dimensions

  • Vertical alignment (plumb bob / level)

  • No gaps or leakage joints

• Apply shuttering oil

5. Pre-Concreting Checks (Very Important)

• Steel and shuttering approved by engineer

• Check:

  • Line, level, plumb

  • Cover blocks

  • Cleanliness inside shutter

• Remove debris, water, or loose materials

6. Concreting

• Concrete poured in layers (usually ≤ 1.5 m)

• Avoid free fall > 1.5 m

• Use chute or tremie if required

7. Compaction

• Use needle vibrator

• Vibrate uniformly without touching reinforcement excessively

• Avoid over-vibration (causes segregation)

8. Finishing & Top Leveling

• Finish top surface smoothly

• Mark construction joint if beam/slab is cast later

9. Curing

• Start curing after initial set (8–12 hours)

• Keep column wet for minimum 7 days (OPC)

10. De-shuttering

• Column shutters removed after 16–24 hours

• Check surface:

  • Honeycombing

  • Alignment

  • Dimensions

One-Line Interview Answer (Perfect)

Column casting is the process of placing and compacting concrete in column formwork with reinforcement to form a vertical RCC load-bearing member.

Common Interview Follow-Up Questions

Q: Why is free fall of concrete limited?
A: To prevent segregation.

Q: What happens if column is not vertical?
A: It causes eccentric loading and structural issues.