Nondestructive Testing to Identify Delaminations Between HMA Layers, Volume 2

Asphalt pavements with delamination problems experience considerable early damage because delaminations provide paths for moisture damage and the development of damage such as stripping, slippage cracks, and pavement deformation. Early detection of the existence, extent, and depth of delaminations in asphalt pavements is key for determining the appropriate rehabilitation strategy and thus extending the life of the given pavement. This report presents the findings of the first two phases of Strategic Highway Research Program 2 Renewal Project R06D, Nondestructive Testing to Identify Delaminations Between HMA Layers. The main objective of the project was to develop nondestructive testing (NDT) techniques capable of detecting and quantifying delaminations in hot-mix asphalt (HMA) pavements. The NDT techniques should be applicable to construction, project design, and network-level assessments. During Phase 1 of the project, the research team evaluated NDT methods that could potentially detect the most typical delaminations in asphalt pavements. Both laboratory and field testing were conducted during this task. Based on the findings from this testing, the manufacturers of two promising technologies conducted further development of their products to meet the goals of this project in Phase 2. The two technologies advanced in this research were ground-penetrating radar (GPR) and impact echo/spectral analysis of surface waves (IE/SASW). Additionally, the project developed guidelines and piloted both NDT technologies in collaboration with highway agencies. Once completed, the results from this additional scope of work will be published as an addendum to this report.