Transactions on Engineering and Computer Science

Abstract 

Reusing asphalt pavement (RAP) has been utilized in producing new bituminous mixes for last several years and has turned into a popular topic in pavement organizations. However, worries from its behavior in the field have been still standing. The main objective of this research is investigating the long-term performance of asphalt overlays containing RAP in flexible pavement rehabilitation using data from Long Term Pavement Performance (LTPP) program. Many variables are considered such as overlay thickness (51, 127mm), asphalt overlay materials (raw mixtures compared with mixtures including 30% RAP), climate (wet, dry) and pre-overlay curing that means pavement surface handling before rehabilitation by low or heavy grinding. In this article, data from 4 sites were taken to perform analysis where each site consists of 8 sections (4 sections with raw materials and another 4 sections using 30%RAP). These sites were selected due to their similar climate to Egypt. Five performance indicators were chosen including fatigue cracking, longitudinal cracking, transverse cracking, rutting, and roughness. Two statistical analyses were performed on extracted data to determine the priority in performance and the significance in variation. The first analysis was using paired t-tests and pvalues while the second was the analysis of variance (ANOVA). The results of field observations indicated that the RAP sections achieved similar/ better performance as compared with raw sections except for rutting development which increased at using RAP. Moreover, RAP addition in thicker overlay provided lower fatigue cracking progress while thinner overlay for RAP sections provided lower longitudinal cracking development. The pre-overlay handling didn't appear any noticeable difference in fatigue, longitudinal and transverse cracking development. The climate had no obvious effect on fatigue and transverse cracking progress while dry climate provided higher longitudinal cracking and roughness progress for RAP sections. Statically, the variation in pre-overlay curing (from low to heavy) had the highest statistical effect on fatigue and transverse cracking, while rutting and roughness progresses weren't clearly affected by variation in climate, thickness or surface curing before rehabilitation. According ANOVA test, the variation in climate from wet to dry had a significant statistical effect on reducing fatigue cracking and increasing longitudinal cracking. 

Keywords: Rehabilitation; Asphalt overlay; Long term performance; RAP; Cracking; Rutting