Repairing concrete spalling correctly is critical to restoring both durability and structural integrity. In South Africa, repairs must account for local environmental conditions, compliance standards, and long-term performance.
Step 1: Detailed Condition Assessment
Before any repair begins, a proper assessment should determine:
- Extent of spalling and delamination
- Depth of reinforcement corrosion
- Structural significance of the affected area
Testing methods may include:
- Hammer sounding
- Half-cell potential testing
- Cover depth measurement
Step 2: Removal of Damaged Concrete
All unsound concrete must be removed back to sound material. Methods include:
- Hand tools (for minor repairs)
- Mechanical breakers
- Hydro-demolition (for large-scale or sensitive areas)
Step 3: Reinforcement Treatment
Exposed reinforcement must be:
- Cleaned (e.g., grit blasting)
- Assessed for corrosion damage
- Supplemented or replaced if section loss is severe
Anti-corrosion coatings may be applied where appropriate.
Step 4: Application of Repair Systems
Patch Repairs
Used for localised damage with polymer-modified mortars.
Sprayed Concrete (Shotcrete)
Suitable for vertical or overhead surfaces and larger repair zones.
Form-and-Pour Repairs
Used where deeper structural restoration is required.
All materials should comply with relevant durability and compatibility requirements.
Step 5: Protective Measures
To prevent recurrence:
- Apply anti-carbonation coatings
- Install waterproofing systems
- Consider cathodic protection in high-risk environments
Common Failures in Spalling Repairs
Many repairs fail due to:
- Not addressing the root cause (e.g., ongoing corrosion)
- Poor surface preparation
- Incompatible materials
- Lack of protective coatings
Conclusion
Concrete repair is not just about fixing visible damage—it’s about implementing a durable system that addresses underlying causes. Following best practice ensures long-term performance and reduces repeat failures.
References
- SANS 10100: Structural Use of Concrete
- EN 1504: Concrete Repair Systems
- Cement & Concrete SA: Repair Guidelines
- ACI 546R: Guide to Concrete Repair
- The Concrete Institute (South Africa) Technical Resources
