Structural Retrofitting of Columns with High-Strength Concrete Jacketing

By Rakhra Associates – Chandigarh’s Premier Structural Engineering Firm

Introduction

When building columns show signs of distress – from cracking to strength degradation – high-strength concrete jacketing emerges as one of the most reliable and durable retrofitting solutions. This technique has become our go-to method for strengthening critical vertical load-bearing elements across Chandigarh’s aging infrastructure.

This comprehensive guide covers:
✔ When column jacketing becomes necessary
✔ 3 types of concrete jacketing we use
✔ Step-by-step execution process
✔ 5 key advantages over other retrofitting methods
✔ Real-world case studies from Chandigarh projects

1. Signs Your Columns Need Jacketing

Visible Warning Signs

• Spalling concrete exposing reinforcement
• Vertical cracks wider than 0.3mm
• Corroded rebar visible through cracks
• Bulging or buckling of column surface

Structural Indicators

• Load capacity reduced by >25%
• Failed hammer test (hollow sounds)
• Seismic vulnerability assessments

2. Types of High-Strength Concrete Jacketing

Conventional Reinforced Concrete Jacketing

• Materials: M60+ concrete + additional rebar
• Thickness: 75-150mm
• Best for: Severely damaged columns

② Fiber-Reinforced Polymer (FRP) Confined Jacketing

• Materials: Concrete + FRP wraps
• Thickness: 50-100mm
• Best for: Moderate damage in tight spaces

③ Steel-Confined Jacketing

• Materials: Concrete + steel angles/wire mesh
• Thickness: 100-200mm
• Best for: Earthquake-prone structures

3. Our 7-Step Column Jacketing Process

Step 1: Damage Assessment

• Core testing → Rebar scanning → Load capacity analysis

Step 2: Surface Preparation

• Remove loose concrete → Clean rebar → Apply bonding agent

Step 3: Reinforcement Addition

• Install new longitudinal bars + spiral ties

Step 4: Formwork Installation

• Custom shuttering for perfect fit

Step 5: Concrete Pouring

• High-strength concrete (M60-M80) with superplasticizers

Step 6: Curing

• 14-day wet curing for maximum strength gain

Step 7: Quality Testing

• Ultrasonic pulse velocity tests → Load testing

4. Why Choose Concrete Jacketing?

5 Competitive Advantages

1. 50-100% strength increase possible
2. Fire resistance superior to FRP methods
3. 40+ year service life with proper execution
4. Cost-effective for large-scale projects
5. Minimal maintenance required

5. Case Studies: Successful Implementations

🏢 Sector-35 Commercial Complex

• Challenge: 30% strength loss in ground floor columns
• Solution: 100mm M65 jacketing with additional rebars
• Result: Restored full capacity in 2 weeks

🏥 PGI Hospital Auxiliary Building

• Challenge: Seismic vulnerability in critical care wing
• Solution: FRP-confined jacketing (75mm)
• Result: Achieved Zone-IV seismic compliance

🏛️ Heritage Building in Sector-17

• Challenge: Corrosion damage in 70-year-old columns
• Solution: 125mm jacketing with corrosion inhibitors
• Result: Preserved heritage while doubling strength

6. Cost Comparison

Note: Costs vary based on column size and damage severity

7. When is Jacketing the Best Solution?

✅ Ideal For:

• Heavily damaged columns
• Seismic retrofitting projects
• Heritage structures needing preservation
• High-load environments

❌ Not Recommended For:

• Minimal damage (consider CFRP instead)
• Extremely tight spaces
• Temporary structures

Conclusion: Building Column Resilience for Decades

High-strength concrete jacketing remains one of the most dependable solutions for column retrofitting, combining proven technology with long-term performance.