Delamination Survey is a non-destructive assessment method used to detect and evaluate separation or debonding between layers within concrete structures, particularly between the surface layer and underlying concrete. It is commonly used to assess the condition of slabs, bridge decks, and pavement surfaces.
Principle: Delamination occurs when concrete layers lose bond due to corrosion of reinforcement, moisture ingress, or poor construction practices. The survey identifies these hollow or detached areas by detecting changes in sound, vibration, or response under impact.
Equipment: Chain drag tool, hammer, tapping rod, or specialized acoustic/impact testing devices are used depending on the required accuracy and structure type.
Procedure:
Surface Inspection: The concrete surface is systematically inspected in a grid pattern.
Tapping/Impact: A hammer or chain drag is used to strike or drag over the surface.
Sound Evaluation: Solid concrete produces a clear, sharp sound, while delaminated areas produce a hollow or dull sound.
Mapping: The affected areas are marked and mapped to determine the extent and severity of delamination.
Applications:
- Evaluating bridge decks, slabs, and pavement conditions
- Detecting early-stage concrete deterioration
- Assessing repair needs before rehabilitation works
- Monitoring structural health over time
Advantages:
- Simple, quick, and cost-effective method
- Non-destructive and easy to perform in the field
- Helps identify hidden defects beneath the surface
Limitations:
- Depends on operator experience for accurate interpretation
- Limited depth of detection (surface and near-surface only)
- May require confirmation with advanced testing methods for detailed analysis
