Nondestructive Testing to Identify Delaminations Between HMA Layers, Volume 5 - Field Core Verification

Abstract

This Volume I report documents the evaluation of nondestructive testing technologies to detect the extent, depth, and severity of delamination in hot mix asphalt pavements and the development of the technologies to operate full-lane width at safe traveling speed. The evaluation included theoretical modeling, controlled laboratory and full-scale pavement testing at the National Center for Asphalt Technology, and uncontrolled field evaluation in Florida and Kansas. The technologies included ground penetrating radar, infrared thermography, mechanical waves, and deflectometers. The two most promising systems were ground penetrating radar using an air-launched antenna array with frequency sweep measurements and a scanning mechanical wave system measuring impact echo and spectral analysis of surface waves. Ground penetrating radar can test full-lane width at safe traveling speed, identify severe stripping, but it can only identify debonded layers when water was present. The scanning mechanical wave device operates at walking speed and covers half of the lane. Impact echo measurements identified delamination at depths greater than four inches when the pavement was cold and stiff. Spectral analysis of surface waves identified delamination when there was a significant change in the pavement stiffness. Both systems are ready for project-level use but need more data analysis software for network-level assessment. Technical briefs are provided for the most promising systems. A Volume II report covers individual components of the study in more detail and is only available as an electronic file. vi