Detection of subsurface joint deterioration

Results of a blind test evaluation of various nondestructive testing techniques, including well-established methods such as chain dragging, rod sounding, and ground-penetrating radar, compared with an emerging ultrasonic array technology for determining the extent of concrete joint deterioration, are presented. Nondestructive testing at two concrete pavement joints at the Minnesota Road Research Facility was performed, and the results were independently evaluated and submitted to the Minnesota Department of Transportation. Significant discrepancies in subsurface deterioration assessments were observed between these techniques. Forensic evaluation (trenching and coring) was used to resolve the discrepancies in test results. It was concluded that the ultrasound array analysis was the only method that could accurately determine the horizontal extent of the deterioration otherwise undetected by the other available nondestructive evaluation methods. Additionally, ultrasonic tomography analysis was able to determine the depth of the deterioration. These results make this emerging technology an attractive alternative to traditional nondestructive testing methods for assessment of concrete pavement joints.