(SEM VI) THEORY EXAMINATION 2024-25 REPAIR AND REHABILITATION OF STRUCTURES

BCE063 – REPAIR AND REHABILITATION OF STRUCTURES

Time: 3 Hours | Max Marks: 70

SECTION A – Short Answer Questions

(2 × 7 = 14 marks | Attempt ALL)

 Write definition + 1–2 key points

Important Questions with Ready Explanations

1. Common Causes of Deterioration in RCC Structures

Two common causes are:                                            Corrosion of reinforcement

Poor quality concrete / improper curing

2. Factors Affecting Permeability of Concrete

Water–cement ratio                                             Degree of compaction

Curing conditions                                                Presence of cracks

3. Ferrocement and Its Uses

Ferrocement is a thin composite made of cement mortar reinforced with wire mesh.
Uses: Water tanks, shells, repair works, roofing units.

4. Repairs for Marine-Exposed Structures

Marine structures need:                                       Anti-corrosion treatments

Protective coatings                                              Cathodic protection

Use of special concrete with low permeability

5. Low Member Strength

Low member strength means insufficient load-carrying capacity due to deterioration or design deficiency.
Addressed by: Jacketing, FRP wrapping, steel plates, section enlargement.

6. Role of Data Acquisition Systems in Health Monitoring

They collect, store, and analyze structural data such as strain, vibration, and displacement for early damage detection.

7. Difference Between Repair and Rehabilitation

Repair: Restores original condition

Rehabilitation: Improves strength, durability, and service life beyond original state

SECTION B – Medium Answer Questions

(7 × 3 = 21 marks | Attempt ANY THREE)

Write cause → explanation → example

1. Causes of Distress in Concrete Structures        Poor design and detailing

Construction defects                                            Environmental exposure

Overloading                                                         Lack of maintenance

Examples: Cracks, spalling, deflection, corrosion.

2. Mechanism of Corrosion in RCC                      Carbonation or chloride ingress reduces alkalinity

Passive layer on steel breaks                                Electrochemical reaction causes rust

Rust expansion leads to cracking and spalling    Corrosion reduces durability and service life.

3. Short Notes

(i) Fiber Reinforced Concrete (FRC)
Concrete mixed with fibers to improve tensile strength, crack resistance, and ductility.

(ii) Bacterial Concrete
Uses bacteria to heal cracks by calcium carbonate precipitation.

4. Repair vs Strengthening | Retrofitting

Repair: Fixes damage            Strengthening: Increases load capacity

Retrofitting: Used when structure is unsafe under revised loads (earthquake, code changes)

5. Non-Destructive Testing (NDT) Techniques

Rebound hammer                        Ultrasonic pulse velocity

Half-cell potential                        Ground-penetrating radar

Different techniques suit different structures depending on damage type.

SECTION C – Long Answer (Condition Assessment)

(7 marks)

1. Major Causes of Deterioration & Environmental Effects

Chemical attack                           Freeze-thaw action

Chloride ingress                          Sulphate attack

Environment accelerates corrosion and cracking.

2. Condition Assessment Procedure

Step-by-step:                              Visual inspection

Preliminary investigation            NDT testing

Sampling and lab testing           Structural evaluation

Decision on repair/rehabilitation