PAL

Experiment 2: Identification and Analysis of Corrosion in RC Components

1. Aim

To study and identify the occurrence of corrosion in reinforced concrete (RC) components, analyze its possible reasons, and suggest suitable treatment strategies and preventive measures.

2. Objectives

• To visually identify symptoms of corrosion in RC elements.
• To analyze the possible reasons for corrosion occurrence.
• To record field observations systematically with photographs.
• To suggest treatment and preventive measures.
• To relate the observations with provisions of relevant IS codes.

3. Apparatus / Requirements

• Camera / Smartphone (for capturing photographs)
• Field notebook and pen
• Measuring tape / scale
• Crack width gauge (if available)
• Magnifying glass (optional)
• Relevant IS Codes (e.g., IS 456:2000, IS 15988:2013, IS 5525, etc.)

4. Procedure (Sample – for reference only)

1. Select RC structural components (beams, columns, slabs, staircases, retaining walls, etc.) from nearby buildings/structures.

2. Carefully observe and capture photographs of corrosion symptoms such as:

   • Rust stains on the concrete surface
   • Cracks and spalling exposing reinforcement
   • Loose cover concrete or delamination
3. Record details of each observation in a systematic format (see sample table below).
4. Identify possible causes behind the observed corrosion.
5. Suggest treatment and preventive strategies for each observation.
6. Compare findings with recommendations of relevant IS codes.
7. Consult literature and case studies to better understand advanced repair and rehabilitation practices.

5. Observation & Data Recording (Sample Table – for reference only)

Sr. No.	Location (Building Element)	Symptom of Corrosion	Extent / Severity	Possible Cause	Suggested Remedy
1.	RCC Column at ground floor	Rust stains, cracking of cover concrete	Localized, moderate	Water ingress through cracks, carbonation	Remove loose cover, apply anti-corrosive coating, patch repair with polymer modified mortar
2.	Slab soffit near leakage area	Exposed reinforcement, spalled concrete	Severe	Continuous water leakage, chloride attack	Clean reinforcement, apply corrosion inhibitor, re-cast with micro-concrete
3.	Beam near external wall	Brown streaks, slight delamination	Mild	Poor concrete cover, moisture penetration	Surface coating, sealant application, ensure waterproofing
4.	Staircase landing	Localized corrosion patches	Moderate	Inadequate cover, exposure to wetting and drying cycles	Epoxy grouting, protective coating
5.	Retaining wall face	Rust streaks along vertical cracks	Severe	Aggressive soil, poor drainage	Provide drainage, use cathodic protection, re-concrete damaged portion

Note: Students must fill a minimum of 5–6 entries with photographs attached in their report. The photographs should be properly captured, numbered, labeled, and captioned for clarity.

6. Analysis (Sample – for reference only)

• Identify possible reasons for corrosion:

  • Inadequate cover thickness
  • Use of poor-quality concrete
  • Water seepage/leakage
  • Carbonation and chloride ingress
  • Exposure to aggressive environment (industrial, coastal, or soil conditions)
• Discuss how the defect can reduce service life and strength of the structure.
• Relate observations to IS code recommendations (e.g., cover requirements, durability clauses, repair standards).

7. Treatment Strategies (Sample – for reference only)

• Minor corrosion: Clean surface, apply protective coating.
• Moderate corrosion: Remove loose concrete, clean bars, apply corrosion inhibitor, repair with polymer-modified mortar.
• Severe corrosion: Replace damaged concrete, add reinforcement if required, use micro-concrete/jacketing.

8. Preventive Measures (Sample – for reference only)

• Ensure adequate concrete cover during construction (as per IS 456).
• Use high-quality concrete with low permeability.
• Provide waterproofing and drainage to prevent seepage.
• Use corrosion-resistant steel (CRS/TMT with coating).
• Apply protective coatings and perform regular maintenance checks.

9. Results (Sample – for reference only)

• Students will document:

  • Identified locations of corrosion in RC components.
  • Possible reasons for corrosion occurrence.
  • Suggested remedial and preventive measures.
  • Code-based recommendations and learnings from literature/case studies.

10. References / Suggested Reading

• IS 456:2000 – Code of Practice for Plain and Reinforced Concrete
• “Handbook on Repair and Rehabilitation of RCC Buildings” – CPWD, Govt. of India
• Selected journal papers on crack diagnosis in RC structures

Note: These references are for guidance. Students are encouraged to explore additional books, IS codes, and case studies relevant to the observed cracks.

11. Viva Questions (Sample: for reference only - Do not write in the final repor)

1. What are the main causes of corrosion in RC structures?
2. How does carbonation contribute to reinforcement corrosion?
3. What is the effect of chloride attack on RC?
4. Why is cover thickness important for corrosion resistance?
5. What are some commonly used treatment methods for corroded RC?
6. What preventive strategies can be adopted during construction to reduce corrosion risk?
7. Which IS codes provide guidance on durability and rehabilitation of RC structures?
8. How can case studies help in understanding practical aspects of corrosion management?

---