Structural Performance of Sections Treated with Thin Overlays for Pavement Preservation

Abstract

Over the last decades, increased efforts have been made to identify cost-effective alternatives to achieve a longer pavement life by applying preservation treatments. The application of thin overlays to restore the surface condition of the pavement is widely practiced across the United States. Benefits include a long service life, a better riding surface, reduced noise, grade and slope geometry preservation, recyclability, and fewer maintenance regimes. Although thin overlays can provide significant improvements in both the immediate and long-term functional performance of the pavement, there is little information on how these treatments affect the structural performance of pavements. Although not expected to significantly improve structural capacity, thin overlays may be able to maintain a structurally sound pavement in good condition for longer. The objective of this study was to evaluate the structural performance of pavements treated with thin overlays as a preservation technique. To accomplish this objective, falling weight deflectometer and field performance data from six full-scale thin overlay test sections and a control section with high cracking were collected and analyzed over a period of nearly 8 years. The results indicated that, based on deflection basin parameters (DBPs), the treated sections had better performance and were projected to reach the “warning” zone much later than the untreated sections. The observed surface condition correlated well with these parameters as, in general, sections with higher DBPs also exhibited more cracking and rutting. The test sections continue to be monitored to fully quantify the extent of the structural benefit obtained from the treatments.