Evaluation of Ultrasonic Technique for Detecting De lamination in Asphalt Pavements

De lamination that occurs because of layer debonding or stripping between layers of hot-mix asphalt can cause distresses such as longitudinal cracking in the wheelpath and tearing in the surface. Because these distresses cannot be detected by visual inspection of the pavement, highway agencies are interested in finding nondestructive methods for detecting delamination to maintain roadway networks. A study evaluated an ultrasonic tomography device for detecting the type and severity of delamination with various focusing techniques. A comparison of blind ultrasonic tomography testing results versus construction of bonded and debonded conditions showed that ultrasonic tomography could detect delamination between new and old asphalt layers, as well as delamination of lifts within new asphalt pavement. B- and D-scan methods with the focusing technique of synthetic aperture were able to identify delamination between new and old asphalt interfaces, and a new focusing method developed at the University of Minnesota was used to identify delamination within asphalt lifts.