Surface Crack Detection in Precasted Slab Track in High-Speed Rail via Infrared Thermography

Area of Science:

• Civil Engineering
• Materials Science
• Non-destructive Testing

Background:

• Surface cracks in ballastless track slabs significantly compromise high-speed railway (HSR) serviceability and durability.
• Accurate and efficient detection of these cracks is crucial for maintaining HSR infrastructure integrity.

Purpose of the Study:

• To propose and validate an infrared thermography (IRT)-based method for detecting surface cracks in HSR track slabs.
• To establish the relationship between detectable crack width and ambient temperature using a finite element model.

Main Methods:

• Development of a three-dimensional finite element (FE) model simulating IRT detection of concrete slabs with surface cracks.
• Parametric study using the FE model with measured thermodynamic parameters.
• Validation through scale model tests and field tests.

Main Results:

• The FE model indicates that cracks of 0.2 mm width are detectable when ambient temperature exceeds 15 °C.
• Scale and field tests confirmed IRT's effectiveness, locating cracks as small as 0.14 mm at ambient temperatures of 20 °C and above.

Conclusions:

• Infrared thermography is a viable and effective non-destructive testing method for identifying critical surface cracks in HSR ballastless track slabs.
• The study provides a temperature-dependent threshold for crack detection using IRT, aiding in infrastructure maintenance planning.