Evaluation of Application of Thin HMA Overlay on the Existing Flexible Pavement for High-Traffic-Volume Rural Highways

Abstract

Thin hot mix asphalt (HMA) overlay of flexible pavement is a conventional method for preventive maintenance of the existing flexible pavements especially in  high-traffic-volume rural roads. In this research, MEPDG software is used to  investigate the effects of thin HMA overlay on the pavement performance improvement by considering various scenarios for applying overlay layer under dierent climatic  conditions. These scenarios consist of applying dense graded asphalt concrete  (DGAC) and gap graded asphalt rubber concrete (GGARC) as thin overlay layer with and without thin milling the existing asphalt concrete layer. The analyses are made for the climatic conditions of three cities in Iran. According to the obtained results, the effect of mean annual air temperature on thin HMA overlay performance is more than rainfall. The results also indicate that the performance of GGARC in retention of fatigue cracking is better than DGAC. Furthermore, the results suggest that thin HMA overlay remarkably increases the service life of existing flexible pavement for heavy trac rural highways.