A complete collection of essential concepts in Construction, Structural Engineering, Surveying, and Concrete Technology.

A. Basic Construction & Materials

1. What is the unit weight of concrete?

Plain Cement Concrete (PCC): 24 kN/m³

Reinforced Cement Concrete (RCC): 25 kN/m³

2. What is the standard size of a brick in India?

As per IS 1077:1992:

Without mortar: 190 × 90 × 90 mm

With mortar: 200 × 100 × 100 mm

3. What is the minimum curing period for concrete?

According to IS 456:2000:

OPC: 7 days

PPC or blended cement: 10 days

Hot & dry weather: 14 days

4. What is the water–cement ratio?

The W/C ratio is the ratio of water to cement by weight.
Typical values: 0.40 to 0.50 for good-strength concrete.

5. What is a slump test? Why is it performed?

A slump test checks the workability of fresh concrete.

Slump ValueWorkabilityApplication
> 150 mmHighPumping concrete
75–150 mmMediumGeneral construction
< 75 mmLowRoad construction

6. Types of foundations

Shallow foundations: Spread footing, raft, combined footing

Deep foundations: Pile, pier, well foundation

7. What is the compressive strength of M20 concrete?

20 MPa (N/mm²) at 28 days.

8. Meaning of M25 concrete

M = Mix

25 = 25 MPa strength at 28 days

Nominal proportion: 1 : 1 : 2

9. Common types of cement

OPC (33, 43, 53 grade)

PPC

Rapid Hardening Cement

Sulphate Resistant Cement

White Cement

10. One-way vs Two-way slab

One-way slab: Longer span / shorter span > 2

Two-way slab: Ratio < 2

11. Types of beams

Simply supported, cantilever, continuous, fixed, overhanging.

12. What is bleeding in concrete?

Water rises to the surface due to excess mixing water.

13. What is honeycombing?

Void formation in hardened concrete due to poor compaction.

14. What is a cantilever beam?

A beam fixed at one end and free at the other.

15. Common tests on cement

Fineness, consistency, setting time, compressive strength, soundness.

16. Lap length in reinforcement

Tension: 60d

Compression: 50d

17. Types of concrete grades

Ordinary: M10, M15, M20

Standard: M25–M40

High strength: M45 and above

18. What is BBS?

Bar Bending Schedule – a detailed list of reinforcement size, shape, and cutting length.

19. What is a plinth beam?

A beam at plinth level to prevent differential settlement.

20. Minimum foundation depth

Normal buildings: 1.2 m

High-rise: Depends on soil and load calculations.

21. PCC vs RCC

PCC: No reinforcement

RCC: Contains steel bars for tensile strength

22. Types of loads on structures

Dead load, live load, wind load, seismic load.

23. Nominal mix vs design mix

Nominal mix: Predefined ratios (e.g., 1:1.5:3)

Design mix: Proportions finalized through lab testing.

24. Density of steel

7850 kg/m³

25. Standard plaster thickness

Internal: 12–15 mm

External: 20–25 mm

B. Structural Engineering

1. What is structural engineering?

It focuses on designing safe structures (buildings, bridges, towers) capable of resisting loads.

2. Beam vs Column

Beam: Horizontal, resists bending

Column: Vertical, resists compression

3. Types of structural loads

Dead, live, wind, seismic, snow, impact.

4. Tensile vs Compressive stress

Tensile: Stretches material

Compressive: Shortens material

5. Shear force & bending moment

Shear force: Causes sliding between sections

Bending moment: Causes bending

6. Moment-curvature relationship

Shows how a beam bends under a given load.

7. Cantilever beam

Fixed at one end, free at the other.

8. Modulus of Elasticity (E)

Stress/strain ratio in the elastic range.

9. Elastic vs Plastic deformation

Elastic: Temporary

Plastic: Permanent

10. Formula for bending stress

σ=M⋅yIσ = \frac{M \cdot y}{I}

11. Short vs Long columns

Short: Fail by crushing

Long: Fail by buckling

12. Lateral torsional buckling

Beam twists and bends sideways due to inadequate lateral support.

13. Types of slabs

One-way, two-way, flat slab, waffle slab.

14. Yield vs Ultimate strength

Yield: Start of permanent deformation

Ultimate: Maximum stress before failure

15. What is torsion?

Twisting caused by torque.

16. Purpose of reinforcement

Concrete is weak in tension; steel bars provide tensile strength.

17. Methods of column design

Working Stress Method, Limit State Method.

18. Types of foundations in structural design

Shallow (spread, raft) and deep (pile, drilled shaft).

19. Combined footing

Supports two or more closely-spaced columns.

20. Importance of shear stress–strain curve

Helps predict material behavior under shear loads.

21. Types of steel sections

I-beam, channel, angle, T-section, box section.

22. Elastic vs Plastic bending

Elastic: Temporary bend

Plastic: Permanent deformation

23. RCC slab

Concrete slab reinforced with steel bars.

24. Fixed vs simply supported beam

Fixed: Restrained at both ends

Simply supported: Free to rotate, no moment resistance

25. Importance of moment of inertia

Indicates a section’s resistance to bending.

C. Surveying & Levelling

1. What is surveying?

Measurement and mapping of land for defining boundaries, elevations, and positions.

2. Surveying vs Levelling

Surveying: Measures distances, angles, positions

Levelling: Measures height differences

3. Types of surveying

Land, geodetic, hydrographic, construction, topographic, mining, photogrammetry.

4. Surveying instruments

Theodolite, total station, GPS, dumpy level, auto level, compass, measuring chain/tape.

5. Benchmark

A reference point of known elevation.

6. Levelling instrument

Used to determine height differences.

7. Dumpy level vs automatic level

Dumpy: Manual leveling

Automatic: Self-leveling, more accurate

8. Line of sight

Straight line between instrument and target.

9. Types of levelling

Differential, trigonometric, barometric, spirit, digital.

10. Principle of levelling

Liquid surface always forms a horizontal plane.

11. Purpose of levelling rod

To measure height difference relative to the instrument.

12. Contour line

Line joining points of equal elevation.

13. Foresight vs Backsight

FS: Taken at unknown point

BS: Taken at benchmark or known point

14. Levelling staff

Graduated rod used for BS/FS readings.

15. Reduced Level calculation

RLnew=RLold+BS−FSRL_{\text{new}} = RL_{\text{old}} + BS - FS

16. Earth curvature error

Occurs over long distances; must be corrected.

17. Refraction error

Light bends due to temperature variation, affecting readings.

18. Closed loop levelling

Start and end at the same benchmark to verify accuracy.

19. Common levelling errors

Instrumental, personal, collimation, refraction errors.

20. Trigonometric levelling

Uses angles and distances to compute elevations.

21. Role of theodolite

Measures both horizontal and vertical angles.

22. Total station

Combines EDM and theodolite; used for precise surveying.

23. Simple vs digital level

Simple: Manual readings

Digital: Electronic, minimizes human error

24. Corrections in levelling

Curvature, refraction, collimation, instrumental.

25. Plumb bob

Ensures instrument is vertically aligned.

D. Concrete Technology

1. Main ingredients of concrete

Cement, fine aggregates, coarse aggregates, water, admixtures.

2. Role of cement

Acts as a binder and gains strength through hydration.

3. Water–cement ratio

Controls strength and workability.

4. Nominal mix vs design mix

Nominal—fixed ratios.
Design—lab-tested proportions.

5. Importance of curing

Maintains moisture for strength gain and durability.

6. Types of cement

OPC, PPC, rapid hardening, SRC, low heat, high alumina, white cement.

7. OPC vs PPC

OPC: Faster strength gain

PPC: Better durability, lower heat of hydration

8. Importance of admixtures

Modify workability, strength, setting time, durability.

9. Types of admixtures

Plasticizers, superplasticizers, accelerators, retarders, air-entraining, waterproofing.

10. Aggregate grading

Ensures proper packing and strength.

11. Types of aggregates

Fine, coarse, and special aggregates.

12. Workability

Ease of mixing, placing, and finishing.

13. Reinforced vs plain concrete

PCC: No reinforcement

RCC: Steel bars included

14. Factors affecting concrete strength

W/C ratio, cement type, curing, aggregates, admixtures.

15. Shrinkage

Volume reduction during drying.

16. Slump test vs compaction factor test

Slump: Consistency/workability

Compaction factor: Degree of compaction

17. Purpose of reinforcement

To resist tensile stresses.

18. Importance of curing time

7–28 days depending on desired strength.

19. PCC vs RCC

PCC: no steel
RCC: steel for tensile strength

20. Effect of temperature on concrete

High temperature → rapid evaporation
Low temperature → slow hydration

21. Causes of concrete cracks

Shrinkage, overloading, poor curing, temperature, settlement.

22. Role of fly ash

Improves workability and long-term strength.

23. Ordinary vs high-strength concrete

<40 MPa = ordinary

40 MPa = high strength

24. Role of silica fume

Increases strength and reduces permeability.

25. Ways to prevent cracking

Proper mix design, curing, joints, reinforcement, and temperature control.