Nondestructive Testing Technology for Quality Control and Acceptance of Flexible Pavement Construction
Applied Research Associates, Inc.
Mr. Harold L. Von Quintus
The project final report is available as NCHRP Report 626, NDT Technology for Quality Assurance of HMA Pavement Construction.
Test methods used for in-place quality control and acceptance of individual flexible pavement layers and of new and rehabilitated flexible pavement systems have changed little in past decades. Such quality control and acceptance operations typically rely on nuclear density measurements or the results of testing conducted on pavement cores. Roughness measurements are often used to confirm that the newly constructed pavement has an adequate initial smoothness.
More recently, nondestructive testing (NDT) methods, including lasers, ground-penetrating radar, falling weight deflectometers, penetrometers, and infrared and seismic technologies, have been significantly improved and have shown potential for use in the quality control and acceptance of flexible pavement construction. Furthermore, the Mechanistic-Empirical Pavement Design Guide uses pavement layer stiffness as a key material property. This has led to increased measurement of layer moduli by owner agencies, an activity that heretofore was not a typical component in the acceptance of a completed project.
This research investigated the application of existing NDT technologies for measuring the quality of flexible pavements. Promising NDT technologies were assessed on field projects for their ability to evaluate the quality of pavement layers during or immediately after placement or to accept the entire pavement at its completion. The results identified several NDT technologies ready and appropriate for implementation in routine, practical quality control and acceptance operations.
The objectives of this research were to (1) conduct a field evaluation of selected NDT technologies to determine their effectiveness and practicality for quality control and acceptance of flexible pavement construction and (2) based on the field evaluation results, recommend appropriate test protocols. The first phase of the project will identify existing NDT technologies with potential for in-situ testing of flexible pavement layers, including HMA, base, and subgrade, during new construction and HMA overlays during rehabilitation, and of the entire flexible pavement system at its completion. In selecting NDT technologies for field evaluation in Phase II, emphasis was placed on those judged ready and appropriate for implementation in flexible pavement construction.