الفهرس 
CHAPTER (1): IntroductionOnly 14 pages are availabe for public view
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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 (virgin 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 study, data from 6 sites are
taken to perform analysis where each site consists of 8 sections (4 sections with
virgin materials and another 4 sections using 30%RAP). These sites are selected
due to their similar climate to Egypt. Five performance indicators are chosen
including fatigue cracking, longitudinal cracking, transverse cracking, rutting, and
roughness.
Four statistical analyses are performed on extracted data to determine the priority
in performance and the significance in variation. The first analysis is plotting the
extracted data for each investigated parameter on one graph to illustrate the
potential variation. In order to assess the development of performance, significant
performance indicators are generated versus time. The second analysis is using
paired t-tests and p-values. The third analysis is the analysis of variance (ANOVA)
while the fourth analysis is the Friedman test.
The results of field observations indicate that the RAP sections achieve similar/
better performance as compared with virgin sections except for rutting
development which increased at using RAP. Moreover, RAP addition in thicker
overlay provides lower fatigue cracking progress while thinner overlay for RAP
sections provides lower longitudinal cracking development. The pre-overlay
handling doesn’t appear any noticeable difference in fatigue, longitudinal and
transverse cracking development. The climate has no obvious effect on fatigue and
transverse cracking progress while dry climate provides higher longitudinal
cracking and roughness progress for RAP sections.
Statically, the variation in pre-overlay curing (from low to heavy) has the highest
statistical effect on fatigue and transverse cracking, while rutting and roughness
progresses aren’t clearly affected by variation in climate, thickness or surface
curing before rehabilitation. According to ANOVA test, the variation in climate
from wet to dry has a significant statistical effect on reducing fatigue cracking and
increasing longitudinal cracking. For the Friedman test, the best performance is for
the thicker overlay against fatigue cracking, rutting, and roughness. Heavy preoverlay
curing has the lowest ranks especially with 127-mm thickness against
fatigue cracking, rutting, and roughness. Low grinding and 51-mm thickness are
the best opportunity for RAP sections against both of longitudinal and transverse
cracking.