PAL

Experiment 5: Structural Health Monitoring and Non-Destructive Testing (NDT)

1. Aim

To perform structural health monitoring and non-destructive testing (NDT) on RC structures to identify defects such as cracks, corrosion, and material deterioration, and to suggest remedial and preventive measures.

2. Objectives

• To understand principles of structural health monitoring (SHM).

• To demonstrate and perform NDT techniques:

  • Rebound Hammer Test (surface hardness and quality of concrete)
  • Ultrasonic Pulse Velocity (UPV) Test (internal defects and uniformity)
  • Half-Cell Potential Measurement (corrosion assessment of reinforcement)
• To record observations systematically with properly captured photographs.
• To analyze test results in light of IS code provisions and case studies from literature.

3. Theoretical Background

• Structural Health Monitoring (SHM): Systematic assessment of structural condition to detect deterioration and prevent failures.

• Rebound Hammer Test: Measures surface hardness of concrete and provides an estimate of compressive strength.

  • IS Code: IS 516 (Part 5/Sec 4) 2020

• Ultrasonic Pulse Velocity (UPV) Test: Measures the velocity of ultrasonic waves through concrete to detect cracks, voids, or non-uniformity.

  • IS Code: IS 516 (Part 5/Sec 1): 2018
• Half-Cell Potential Measurement: Detects likelihood of reinforcement corrosion based on electrochemical potential.
  • IS Code: IS 516 (Part 5/Sec 2): 2021
• Students are encouraged to consult case studies in literature to understand practical SHM applications and remedial strategies.

4. Procedure (Sample – for reference only)

1. Select RC members (beams, slabs, columns, walls) for NDT.

2. Rebound Hammer Test:

   • Clean surface of concrete.
   • Take multiple readings at each location and calculate average rebound index.

3. UPV Test:

   • Place transducers on opposite faces of the member.
   • Record pulse velocity at multiple points.

4. Half-Cell Potential Measurement:

   • Connect reference electrode to reinforcement.
   • Measure potential at several locations to identify corrosion-prone areas.
5. Record all observations systematically with properly captured, labelled, numbered, and captioned photographs.
6. Analyze results to identify defects, estimate severity, and suggest remedial or preventive measures.

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

Sr. No.	Location / Member	Test Type	Reading / Value	Interpretation / Defect Indication	Suggested Action
1	Beam near support	Rebound Hammer	35–40	Good quality concrete	No immediate action
2	Slab soffit	UPV	3.2 km/s	Minor internal cracks	Monitor and repair if cracks propagate
3	Column exterior	Half-Cell Potential	-350 mV	Corrosion likely	Apply corrosion inhibitor, patch repair
4	Wall	Rebound Hammer	25	Low strength area	Strengthening / concrete repair

Students must record a minimum of 5–6 locations/tests, with photographs properly captured, numbered, labelled, and captioned in their report.

6. Analysis (Sample – for reference only)

• Compare measured readings with acceptable ranges in IS codes.
• Identify areas with probable material deterioration or reinforcement corrosion.
• Correlate results from different NDT methods for validation.
• Include insights from at least one relevant case study in literature.

7. Treatment Strategies (Sample – for reference only)

• Surface repair or patching for localized defects.
• Corrosion inhibitors or protective coatings for reinforcement.
• Structural strengthening using external supports or fiber-reinforced polymers.
• Implement preventive monitoring for long-term structural health.

8. Results (Sample – for reference only)

• Defects detected and severity assessment.
• Recommendations for remediation.
• Preventive maintenance suggestions.
• Reference to IS codes and literature for validation.

9. References / Suggested Reading

• Rebound Hammer Test – IS 516 (Part 5/Sec 4): 2020
• Ultrasonic Pulse Velocity (UPV) Test – IS 516 (Part 5/Sec 1): 2018
• Half-Cell Potential Measurement – IS 516 (Part 5/Sec 2): 2021
• “Non-Destructive Testing of Concrete” – P. Perumpral
• NDT method manuals

Note: Students should include additional references or manuals relevant to the NDT methods used in their experiments, and consult literature/case studies for deeper understanding.

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

1. What is structural health monitoring, and why is it important?
2. How does the rebound hammer test indicate concrete strength?
3. What does UPV testing detect in concrete?
4. How does half-cell potential measurement identify reinforcement corrosion?
5. Which IS codes provide guidance for NDT methods?
6. Can you cite a real-life example where NDT helped prevent structural failure?
7. Why is it recommended to use multiple NDT techniques together?

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