Lunch and Learn: Nondestructive Testing

Although visual inspections remain the primary method for bridge deck evaluation, they fail to detect hidden deterioration.

Rapid-scanning nondestructive evaluation (NDE) techniques are gaining popularity, but their reliability compared with traditional methods is unclear. This study aimed to determine the reliability of multiple NDE methods for detecting deterioration in concrete bridge decks. This study focused on an interstate bridge for which both in-depth and rapid-scanning NDE evaluations were conducted over 6 years. Inspection data from consultants employing various methods, including manual sounding, infrared thermography, automated sounding, and ground penetrating radar, were compared with ground truth coring results.

The study revealed significant inconsistencies in results across all methods and consultants. Manual chain drag sounding offered reliable results, followed by automated sounding with potential for improvement. Infrared thermography exhibited uniformly poor performance in detecting delamination. Limited evaluation of the emerging time-lapse infrared thermography looked promising, but further improvement is needed.
Matching researchers’ expectations, the literature shows that although this study employed the most robust ground truth comparison in a field study compared with the existing literature, limitations still hinder the formation of definitive conclusions.
These indefinite conclusions highlight the challenge in field studies where getting numerous ground truth cores for statistical significance is impractical. Although no technology was identified as ideal to serve as the control, this study discusses meaningful ways to improve the reliability of some promising NDE methods.

This Although visual inspections remain the primary method for bridge deck evaluation, they fail to detect hidden deterioration.
Rapid-scanning nondestructive evaluation (NDE) techniques are gaining popularity, but their reliability compared with traditional methods is unclear. This study aimed to determine the reliability of multiple NDE methods for detecting deterioration in concrete bridge decks. This study focused on an interstate bridge for which both in-depth and rapid-scanning NDE evaluations were conducted over 6 years. Inspection data from consultants employing various methods, including manual sounding, infrared thermography, automated sounding, and ground penetrating radar, were compared with ground truth coring results.

The study revealed significant inconsistencies in results across all methods and consultants. Manual chain drag sounding offered reliable results, followed by automated sounding with potential for improvement. Infrared thermography exhibited uniformly poor performance in detecting delamination. Limited evaluation of the emerging time-lapse infrared thermography looked promising, but further improvement is needed.
Matching researchers’ expectations, the literature shows that although this study employed the most robust ground truth comparison in a field study compared with the existing literature, limitations still hinder the formation of definitive conclusions.
These indefinite conclusions highlight the challenge in field studies where getting numerous ground truth cores for statistical significance is impractical. Although no technology was identified as ideal to serve as the control, this study discusses meaningful ways to improve the reliability of some promising NDE methods.

This study recommended developing a qualifying mockup testing program for NDE methods, operators, and equipment before contracts can be awarded. The study also recommended developing specifications and engineering guidance for NDE methods.