Study of Best Practices for Pre-Overlay Repair and Asphalt Overlay

Asphalt overlay on existing asphalt and concrete pavements is one of common pavement rehabilitation methods. The performance of asphalt overlay is affected by many factors and varies significantly. This study investigated the factors influencing the performance of overlay. Performance of overlays on existing asphaltic and concrete pavements was reviewed and analyzed. For asphalt overlay of existing concrete pavements, it was found that overlays using doweled concrete to patch the existing concrete pavement performed best, followed by those using non-doweled concrete patching and then asphaltic patching. The transverse cracking development rate in asphalt overlay decreases with the increase of overlay thickness. The current international roughness index (BRI) of overlay is highly correlated with initial IRI of overlay right after placement of overlay. The roughness prediction model in NCHRP 1-37A design guide was calibrated using data collected in Wisconsin. For asphalt overlay on existing asphalt pavements, the longitudinal cracking development rate decreases when the ratio of overlay thickness to milling depth increases.