Lecture Notes on Building Cracks

Introduction

• Building a dream house is a common goal but maintaining it is a challenge.
• Structural safety and crack-free buildings are essential.
• Focus on types of cracks, preventive measures, and rectification methods.

Definition of Crack

• Crack: Complete or incomplete separation of concrete or wall into two or more parts.
• Causes: Chemical reactions, temperature changes, faulty design, poor quality materials, improper construction, foundation movement, poor maintenance, vegetation.

Types of Cracks

Structural Cracks

• Foundation Settlement: Low soil bearing capacity, heavy rain, or floods leading to diagonal settlement cracks.
• Over Design and Detailing: Inappropriate structural designs.
• Overloading: Excessive load on structural members.
• Construction Joints: Incorrectly constructed joints.
• Openings: Large or numerous openings.
• Retrofitting Techniques: Required to prevent building collapse.

Structural Elements

• Beams:
  • Flexural Cracks: Due to poor design or insufficient reinforcement.
  • Shear Cracks: Caused by lack of shear reinforcement.
  • Corrosion Cracks: Result from corrosion of reinforcement bars.
• Columns:
  • Horizontal and Diagonal Cracks: Insufficient moment/load carrying capacity or improper reinforcement.
  • Corrosion Cracks: Insufficient concrete cover leading to reinforcement corrosion.
• Roof Slabs:
  • Structural Cracks: Poor design or insufficient reinforcement.
  • Shrinkage Cracks: Caused by temperature changes and improper curing.

Non-Structural Cracks

• Masonry Cracks: Can result from foundation settlement and temperature variations.
• Sill and Lintel Level Cracks: Occur due to weather changes affecting wooden frames.
• Plastic and Drying Shrinkage Cracks: Rapid water loss or insufficient curing.
• Air or Joint Cracks: Poor plastering or bonding between elements.

Prevention and Rectification

• Prevention:

  • Proper soil analysis and construction techniques.
  • Adequate reinforcement and design considerations.
  • Proper curing and maintenance practices.

• Rectification of Cracks:

  • Clean and drill the crack area, remove plaster around it, cure with water.
  • Use crack-filling materials such as non-string grouts, epoxy resins, or quick-setting cement.
  • Structural cracks require specialized retrofitting by experts.

Conclusion

• Importance of immediate rectification of structural cracks.
• Use proper techniques and consult experts for significant issues.
• Encourage viewers to engage with further queries and suggestions.