📘 50 Civil Engineering Interview Questions & Answers #civilengimeering

🚧 50 Civil Engineering Interview Questions & Answers 🏗️
by The RK Multiverse

1. What is RCC and PCC?

RCC contains steel reinforcement to resist tension, while PCC has no reinforcement.

2. What is workability of concrete?

Ease of mixing, placing, compacting, and finishing concrete.

3. What is curing?

Maintaining moisture and temperature for strength gain.

4. Minimum curing period?

7 days (OPC), 10 days in hot weather.

5. Compressive strength?

Ability to resist axial load (MPa).

6. Slump test?

Measures workability of fresh concrete.

7. Purpose of foundation?

Transfers load safely to ground.

8. Retaining wall?

Holds soil and prevents erosion.

9. Concrete mix design?

Proportioning materials for strength and durability.

10. Nominal vs design mix?

Nominal = fixed ratio, Design = calculated.

11. Water-cement ratio?

Ratio of water weight to cement weight.

12. One-way vs two-way slab?

One-way carries load in one direction, two-way in both.

13. M20 concrete?

20 MPa strength after 28 days.

14. Reinforcement?

Steel bars to resist tension.

15. Cube test?

Checks compressive strength.

16. Structural drawing?

Detailed construction drawings.

17. Beam vs column?

Beam = horizontal, Column = vertical.

18. Dead vs live load?

Dead = permanent, Live = temporary.

19. Survey?

Establishes boundaries and levels.

20. Plinth beam?

Transfers wall load to foundation.

21. Aggregates?

Coarse (>4.75mm) & Fine (<4.75mm).

22. Prestressed concrete?

Concrete with induced internal stresses.

23. Site engineer role?

Supervision, quality, safety.

24. Shear vs retaining wall?

Shear resists lateral force, retaining holds soil.

25. Cantilever beam?

Fixed at one end, free at other.

26. Segregation?

Separation of materials.

27. Bleeding?

Water rising to surface.

28. Honeycombing?

Voids due to poor compaction.

29. Foundations?

Shallow & deep.

30. Column starter?

Initial column extension.

31. Lap length?

Overlap of rebars.

32. Cover block?

Maintains spacing of rebar.

33. Stirrups?

Resist shear in beams.

34. Cube size?

150×150×150 mm.

35. Camber?

Road slope for drainage.

36. Soft story?

Weak floor prone to earthquake damage.

37. BBS?

Bar bending schedule.

38. Stair components?

Tread, riser, landing, handrail.

39. Pile foundation?

Deep foundation system.

40. Shuttering & centering?

Formwork & support system.

41. NDT?

Non-Destructive Testing.

42. Concrete density?

2400 kg/m³.

43. Grouting?

Filling cracks and voids.

44. IS vs IRC?

IS = General, IRC = Road.

45. Expansion joints?

Allow thermal movement.

46. Modular ratio?

Elasticity ratio (steel/concrete).

47. Slump for M20?

75–100 mm.

48. Dev vs lap length?

Development = bond length, Lap = overlap.

49. Concreting steps?

Batching → Mixing → Placing → Compaction → Curing.

50. Minimum RCC grade?

M20.

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Standard Reference Values #civilengineer

 Standard Reference Values

Height of residential building – 3 m

Height of individual storey – 1.5 m

Width of roads – 3 m (typical minimum lane width; arterial roads are wider)

Height of parapet wall – 1 m

Width of staircase in building – 0.9 m (minimum clear width)

Thickness of one brick cement plaster – 12 mm

Density of cement – 1440 kg/m³

Volume of cement per m³ of 1:5 mortar – 0.167 m³

Quantity of cement bags in 1 m³ of 1:5 mortar – 4.18 bags

Bulk density of cement – 1440 kg/m³

Specific gravity of cement – 3.15

Bulk density of fine sand – 1450 kg/m³

Bulk density of coarse sand – 1600 kg/m³

Size of coarse aggregate – 20 mm

Bulk density of aggregate – 1650 kg/m³

Specific gravity of aggregate – 2.6

Water–cement ratio for plain concrete – 0.45–0.6 (acceptable range)

Rate of water absorption for brick – 20%

Porosity of brick – 25%

Crushing strength of brick – >75 kg/cm² (min. for class designation)

Unit weight of mild steel – 7850 kg/m³

Yield strength of mild steel – 250 MPa

Modulus of elasticity of steel – 200 GPa

Poisson’s ratio for steel – 0.3

Ultimate strength of high‐yield steel – 460 MPa

Minimum reinforcement cover in beams – 25 mm

Minimum reinforcement cover in slabs – 20 mm

Minimum reinforcement cover in columns – 40 mm

Minimum reinforcement cover in footings – 75 mm

Maximum diameter of bars in slabs – 8 mm (or ≤ slab thickness/8)

Maximum diameter of bars in beams – 16 mm

Maximum diameter of bars in footings – 20 mm

Clear cover for RCC elements – 20 mm (depends on exposure)

Water–cement ratio for grade M20 concrete – 0.5 (typical) 

Nominal mix ratio for M20 – 1:1.5:3 

Cement content in M20 – ≈330 kg/m³ 

Maximum aggregate size in M20 – 20 mm

Workability (slump) of M20 – 75–100 mm 

Characteristic strength of concrete at 28 days for M20 – 20 MPa

Autoclave efficiency (for AAC blocks) – 70–75%

Compressive strength of AAC blocks – 3.5–7.5 N/mm²

Dry density of AAC blocks – 600–800 kg/m³

Thermal conductivity of AAC – 0.17–0.21 W/m·K

Minimum number of bars used for square column – 4 bars

Minimum number of bars used for circular column – 6 bars

Maximum diameter of bars used in slabs – ≤ (thickness/8)

Maximum diameter of bars used in each bay – 10 mm

Max cover of reinforcement in RCC pile cap – 50 mm

Dimensional tolerance of cube – ±1.25 mm

Final setting time of cement – ≤10 hours

Initial setting time of cement – ≥30 minutes

Standard consistency of cement – 30% water

Specific gravity of PPC – 2.75

Specific gravity of slag – 2.9

Bulk density of PPC – 1120 kg/m³

Bulk density of slag – 1200 kg/m³

Water demand of PPC – 27%

Water demand of slag – 29%

Yield strength of grade M25 steel – 500 MPa

Compressive strength of grade M25 concrete – 25 MPa

Modulus of rupture of grade M25 concrete – 3.5 MPa

Tensile strength of concrete at 28 days – 2.5 MPa

Elastic modulus of concrete – 25 GPa

Poisson’s ratio of concrete – 0.2

Minimum diameter of bars used in T‐beam flange – 12 mm

Minimum diameter of bars used in T‐beam web – 10 mm

Minimum diameter of bars used in stair slab – 8 mm

Minimum diameter of bars used in raft foundation – 12 mm

Minimum diameter of bars used in strip footing – 10 mm

Minimum diameter of bars used in pile – 16 mm

Minimum number of bars used for square column – 4 bars

Minimum number of bars used for circular column – 6 bars

Maximum diameter of bars used in slabs – ≤ (thickness/8)

Maximum diameter of bars used in each bay – 10 mm

Max cover of reinforcement in RCC pile cap – 50 mm

Minimum tensile strength of steel – 415 MPa

Characteristic strength of steel at yield – 460 MPa

Compressive strength of grade M30 concrete – 30 MPa

Flow of concrete mixture – 60–140 mm (flow table)

Final setting time of PPC – 0.5–2 hours

Initial setting time of PPC – 15–30 minutes

Light sand grading zone for RCC – Zone II

Coarse sand grading zone for plaster – Zone I

Flight height of bucket elevator – not specified

Cement content in M20 is typically 310–330 kg/m³ rather than 403 kg/m³ .

Slump for M20 is 75–100 mm, not 25–75 mm .

Maximum diameter in slabs should reference slab thickness (≤ thickness/8) rather than a fixed 8 mm.