✅ Civil Engineering Interview Questions & Answers
Structural Engineering :-
Q1. Difference between one-way and two-way slab?
One-way slab: Ratio of longer span (L) to shorter span (B) > 2. Load carried in one direction only.
Two-way slab: L/B ≤ 2. Load carried in both directions.
Q2. Difference between isolated, combined & raft footing?
Isolated footing: Supports a single column.
Combined footing: Supports 2+ columns (when closely spaced).
Raft footing: Covers entire area under building, supports many columns.
Q3. Types of loads as per IS codes?
Dead load, Live load, Wind load, Earthquake load, Snow load, Impact load.
Q4. Difference between WSM, LSM & ULM?
WSM: Based on elastic theory, stresses kept below permissible.
LSM: Based on safety factors (strength & serviceability), widely used in IS 456:2000.
ULM: Based on ultimate load-carrying capacity, less safe.
Q5. Assumptions in simple bending theory?
Material homogeneous & isotropic.
Plane sections remain plane.
Modulus of elasticity is constant.Stress ∝ strain (Hooke’s law).Grades of Concrete
Stress ∝ strain (Hooke’s law).Gra
M5 , M7.5 , M10, M15, M20 (nominal mix).
M25, M30, M35… up to M80 (design mix).
Q7. Slump test vs compaction factor test?
Slump test: Workability check for medium to high workability concrete.
Compaction factor: Accurate test for low workability (lab test)..
Q8. Nominal mix vs design mix?
Nominal mix: Fixed ratio (e.g., M20 = 1:1.5:3).
Design mix: Proportions based on lab design for required strength.
Q9. Effect of water-cement ratio?
Lower W/C → higher strength, durability.
Higher W/C → segregation, bleeding, low strength.
Q10. Segregation & bleeding in concrete?
Segregation: Separation of coarse aggregate from mortar.
Bleeding: Water rises to surface.
Prevention: Proper mix design, use of admixtures, correct compaction.
Soil Mechanics & Foundation
Q11. Bearing capacity of soil?
Maximum load per unit area soil can carry without failure.
Determined by Plate Load Test, SPT, or Terzaghi’s formula.
Q12. Shallow vs deep foundation?
Shallow: Depth ≤ width (e.g., isolated, combined, raft).
Deep: Depth >> width (e.g., pile, pier, well).
Q13. Methods of soil stabilization?
Mechanical (compaction).
Chemical (lime, cement, fly ash).
Geotextiles, grouting.
Q14. Consolidation of soil?
Gradual compression of soil due to expulsion of water from voids under load. Important for clayey soils.
Q15. Standard Penetration Test (SPT)?
Field test to determine N-value (number of blows required for 30 cm penetration). Used for soil strength & foundation design.
Highway & Transportation
Q16. Flexible vs rigid pavement?
Flexible: Bituminous layers, load distributed by grain-to-grain contact. Cheaper, less durable.
Rigid: Cement concrete slab, load transferred by flexural strength. Expensive, durable.
Q17. Types of road curves?
Horizontal: Simple, compound, reverse, transition.
Vertical: Summit curve, valley curve.
Q18. Tests on bitumen?
Penetration test, Ductility test, Softening point, Flash & fire point, Viscosity test.
Q19. Camber in roads?
Slope provided to road surface (2–3%).
Function: Drainage of rainwater.
Q20. CBR test?
California Bearing Ratio test.
Determines strength of subgrade soil. Used in pavement design.
Surveying
Q21. Methods of leveling?
Direct leveling, Barometric, Trigonometric, Stadia, GPS leveling.
Q22. Plane vs geodetic surveying?
Plane: Small area, earth curvature neglected.
Geodetic: Large area, earth curvature considered.
Q23. Least count of theodolite?
Smallest angle measurable.
Usually 20″ (seconds).
Q24. Sources of errors in surveying?
Instrumental, Natural (temperature, refraction), Personal (sighting errors).
Q25. Principle of total station?
Combines electronic theodolite + EDM (Electronic Distance Measurement).
Measures distance, angles, elevation simultaneously.
Steel Structures
Q26. Bolted vs welded connections?
Bolted: Easy to assemble/disassemble, less strength.
Welded: Permanent, strong, but skilled labor required.
Q27. Slenderness ratio?
Ratio of effective length / least radius of gyration.
High ratio → column prone to buckling.
Q28. Failure modes of steel columns?
Crushing, Buckling, Local buckling, Torsional buckling.
Q29. Limit state of serviceability?
Deflection, vibration, cracking limits for comfort & durability.
Q30. Gusset plate in trusses?
Thick plate connecting truss members at joints.
Water Resources & Environmental
Q31. Specific yield vs specific retention?
Specific yield: Water drained under gravity.
Specific retention: Water retained by soil particles.
Q32. Types of dams?
Gravity, Arch, Buttress, Earthen, Rockfill.
Q33. Bernoulli’s theorem?
Total energy = Pressure head + Velocity head + Elevation head (constant along streamline).
Applications: Hydraulics, pipe flow, turbines.
Q34. Water treatment processes?
Screening → Sedimentation → Coagulation → Filtration → Disinfection.
Q35. BOD & COD?
BOD (Biochemical Oxygen Demand): Oxygen required by microorganisms to decompose organic matter (5 days test).
COD (Chemical Oxygen Demand): Oxygen required to oxidize organic + inorganic matter chemically (2–3 hrs test).
Structural Engineering
Q1. Difference between one-way and two-way slab?
One-way slab: Ratio of longer span (L) to shorter span (B) > 2. Load carried in one direction only.
Two-way slab: L/B ≤ 2. Load carried in both directions.
Q2. Difference between isolated, combined & raft footing?
Isolated footing: Supports a single column.
Combined footing: Supports 2+ columns (when closely spaced).
Raft footing: Covers entire area under building, supports many columns.
Q3. Types of loads as per IS codes?
Dead load, Live load, Wind load, Earthquake load, Snow load, Impact load.
Q4. Difference between WSM, LSM & ULM?
WSM: Based on elastic theory, stresses kept below permissible.
LSM: Based on safety factors (strength & serviceability), widely used in IS 456:2000.
ULM: Based on ultimate load-carrying capacity, less safe.
Q5. Assumptions in simple bending theory?
Material homogeneous & isotropic.
Plane sections remain plane.
Modulus of elasticity is constant.
Stress ∝ strain (Hooke’s law).
Concrete Technology
Q6. Grades of concrete (IS 456:2000)?
M5 , M7.5 , M10, M15, M20 (nominal mix).
M25, M30, M35… up to M80 (design mix).
Q7. Slump test vs compaction factor test?
Slump test: Workability check for medium to high workability concrete.
Compaction factor: Accurate test for low workability (lab test).
Q8. Nominal mix vs design mix?
Nominal mix: Fixed ratio (e.g., M20 = 1:1.5:3).
Design mix: Proportions based on lab design for required strength.
Q9. Effect of water-cement ratio?
Lower W/C → higher strength, durability.
Higher W/C → segregation, bleeding, low strength.
Q10. Segregation & bleeding in concrete?
Segregation: Separation of coarse aggregate from mortar.
Bleeding: Water rises to surface.
Prevention: Proper mix design, use of admixtures, correct compaction.
Soil Mechanics & Foundation
Q11. Bearing capacity of soil?
Maximum load per unit area soil can carry without failure.
Determined by Plate Load Test, SPT, or Terzaghi’s formula.
Q12. Shallow vs deep foundation?
Shallow: Depth ≤ width (e.g., isolated, combined, raft).
Deep: Depth >> width (e.g., pile, pier, well).
Q13. Methods of soil stabilization?
Mechanical (compaction).
Chemical (lime, cement, fly ash).
Geotextiles, grouting.
Q14. Consolidation of soil?
Gradual compression of soil due to expulsion of water from voids under load. Important for clayey soils.
Q15. Standard Penetration Test (SPT)?
Field test to determine N-value (number of blows required for 30 cm penetration). Used for soil strength & foundation design.
Highway & Transportation
Q16. Flexible vs rigid pavement?
Flexible: Bituminous layers, load distributed by grain-to-grain contact. Cheaper, less durable.
Rigid: Cement concrete slab, load transferred by flexural strength. Expensive, durable.
Q17. Types of road curves?
Horizontal: Simple, compound, reverse, transition.
Vertical: Summit curve, valley curve.
Q18. Tests on bitumen?
Penetration test, Ductility test, Softening point, Flash & fire point, Viscosity test.
Q19. Camber in roads?
Slope provided to road surface (2–3%).
Function: Drainage of rainwater.
Q20. CBR test?
California Bearing Ratio test.
Determines strength of subgrade soil. Used in pavement design.
Surveying
Q21. Methods of leveling?
Direct leveling, Barometric, Trigonometric, Stadia, GPS leveling.
Q22. Plane vs geodetic surveying?
Plane: Small area, earth curvature neglected.
Geodetic: Large area, earth curvature considered.
Q23. Least count of theodolite?
Smallest angle measurable.
Usually 20″ (seconds).
Q24. Sources of errors in surveying?
Instrumental, Natural (temperature, refraction), Personal (sighting errors).
Q25. Principle of total station?
Combines electronic theodolite + EDM (Electronic Distance Measurement).
Measures distance, angles, elevation simultaneously.
Steel Structures
Q26. Bolted vs welded connections?
Bolted: Easy to assemble/disassemble, less strength.
Welded: Permanent, strong, but skilled labor required.
Q27. Slenderness ratio?
Ratio of effective length / least radius of gyration.
High ratio → column prone to buckling.
Q28. Failure modes of steel columns?
Crushing, Buckling, Local buckling, Torsional buckling.
Q29. Limit state of serviceability?
Deflection, vibration, cracking limits for comfort & durability.
Q30. Gusset plate in trusses?
Thick plate connecting truss members at joints.
Water Resources & Environmental
Q31. Specific yield vs specific retention?
Specific yield: Water drained under gravity.
Specific retention: Water retained by soil particles.
Q32. Types of dams?
Gravity, Arch, Buttress, Earthen, Rockfill.
Q33. Bernoulli’s theorem?
Total energy = Pressure head + Velocity head + Elevation head (constant along streamline).
Applications: Hydraulics, pipe flow, turbines.
Q34. Water treatment processes?
Screening → Sedimentation → Coagulation → Filtration → Disinfection.
Q35. BOD & COD?
BOD (Biochemical Oxygen Demand): Oxygen required by microorganisms to decompose organic matter (5 days test).
COD (Chemical Oxygen Demand): Oxygen required to oxidize organic + inorganic matter chemically (2–3 hrs test).