(SEM VI) THEORY EXAMINATION 2023-24 REPAIR AND REHABILITATION OF STRUCTURES

KCE063 – Repair and Rehabilitation of Structures (B.Tech Sem VI)

All answers are written in simple, clear, humanized language, not in short points, and are prepared strictly according to the uploaded question paper (2023–24).
Reference: Uploaded Question Paper 

KCE063-REPAIR-AND-REHABILITATIO…

SECTION A

Attempt all questions in brief (2 × 10 = 20 marks)

(a) Measures required to arrest decay

Decay in structures can be arrested by identifying the cause of deterioration, removing damaged material, protecting reinforcement from corrosion, improving drainage, applying protective coatings, and carrying out timely maintenance. Preventive measures are always more effective than corrective repairs.

(b) Classifications of distress

Distress in structures can be classified as structural distress such as cracks, deflection, and failure, and non-structural distress such as dampness, surface cracks, and finishing defects. Distress may also be categorized as physical, chemical, or environmental.

(c) Requirements of a Quality Management System (QMS)

A Quality Management System requires proper planning, defined quality objectives, documentation, trained personnel, inspection and testing procedures, corrective actions, and continuous improvement mechanisms to ensure durability and performance of structures.

(d) Strength of concrete

Strength of concrete refers to its ability to resist applied loads without failure. It is mainly measured in terms of compressive strength, which depends on water-cement ratio, quality of materials, curing, and workmanship.

(e) Epoxy injection method

Epoxy injection is a repair technique in which low-viscosity epoxy resin is injected into cracks to restore structural continuity and strength. It is commonly used for repairing fine cracks in concrete.

(f) Role of dampness in concrete structures

Dampness allows moisture penetration, which accelerates corrosion of reinforcement, reduces durability, causes efflorescence, and leads to weakening of concrete. Controlling dampness is essential for long-term structural health.

(g) Retrofitting

Retrofitting is the process of strengthening or upgrading existing structures to improve their performance, especially against seismic loads, increased loading, or deterioration, without demolishing the structure.

(h) Repair of concrete structures

Concrete structures are repaired by removing damaged concrete, cleaning reinforcement, applying bonding agents, placing repair mortar or concrete, and providing protective coatings to prevent future deterioration.

(i) Strain gauge

A strain gauge is a sensor used to measure strain in structural elements. It works on the principle that electrical resistance changes when the material deforms under load.

(j) Importance of long-term monitoring

Long-term monitoring helps track structural behavior over time, detect early signs of distress, assess effectiveness of repairs, and ensure safety and serviceability throughout the structure’s life.

SECTION B

Attempt any three (10 × 3 = 30 marks)

(a) Categories of inspection based on method and interval

Inspection can be visual, non-destructive, or destructive. Based on interval, inspections are routine, periodic, special, or emergency. Visual inspection identifies surface defects, while non-destructive tests such as rebound hammer and ultrasonic tests assess internal condition without damage.

(b) Quality Assurance (QA) in concrete construction

Quality Assurance ensures that concrete construction meets specified standards through proper material selection, mix design, batching, placing, curing, and testing. QA involves planning, documentation, inspections, testing, and corrective measures to achieve durable and reliable structures.

(c) Facets of maintenance and its importance

Maintenance includes preventive, corrective, and predictive activities. Preventive maintenance avoids future damage, corrective maintenance repairs existing defects, and predictive maintenance uses monitoring data. Proper maintenance increases service life, safety, and cost efficiency.

(d) RCC building distress due to rebar corrosion – diagnosis and repair scheme

For a 20-year-old RCC building with corrosion-induced cracks, diagnosis includes visual inspection, cover measurement, carbonation depth, chloride content, and corrosion assessment.
Repair involves removal of damaged concrete, rust removal, application of corrosion inhibitors, epoxy or polymer repair mortar, and protective coatings. A flowchart showing inspection → diagnosis → repair → monitoring is expected in exams.

(e) Leakage and remedial measures

Leakage is the uncontrolled passage of water through structural elements. Roof and slab leakages are repaired by crack sealing, waterproof membranes, proper slope correction, drainage improvement, and application of protective coatings. Neat sketches are generally drawn in exams.

SECTION C

Attempt any one (10 marks)

(a) Flowchart for pre-repair evaluation of distressed concrete structure

Pre-repair evaluation includes condition survey, damage identification, material testing, structural analysis, cause determination, and selection of suitable repair technique. A flowchart representation shows the systematic approach from inspection to decision-making.

(b) Causes of deterioration due to corrosion

Corrosion occurs when steel reacts with moisture and oxygen, often accelerated by chlorides and carbonation. It leads to expansion of reinforcement, cracking, spalling of concrete, and reduction in load-carrying capacity.