الفهرس 
Long-term pavement performance (LTPPOnly 14 pages are availabe for public view
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Abstract
This study aims to evaluate the impact of maintenance and rehabilitation
treatments on long-term asphalt pavement performance using the data collected in the Specific Pavement Studies: SPS-3 and SPS-5 of the Long Term Pavement Performance (LTPP) program. Pavement performance indicators include fatigue cracking, longitudinal cracking, transverse cracking, rutting, and roughness. There are 26 LTPP SPS-3 sites used in this study. At each site, four maintenance treatments (thin overlay, slurry seal, crack seal, and chip seal) were applied on the pavement sections with an average length of 700ft and an average width of 24ft along with a control section. The SPS-5 concentrates on methods of rehabilitation like overlay thickness (51 and 127mm), asphalt overlay materials (recycled hot mix asphalt (HMA) compared with virgin mix), and pre-overlay treatments (with
or without milling). All of the research sites were wet and dry with no freezing as each of them had a climate that was exactly similar to Egypt’s. There are 8 LTPP SPS-5 sites used in this study. Each site includes 8 test sections (4 using virgin materials and 4 using recycled HMA mix) constructed and operated under the same conditions.
Statistical methods such as average long-term effectiveness increment,
boxplot, and paired-samples t-test were used in this study to completely examine the long-term impact of preventive maintenance treatments (PMTs) on pavement performance. Boxplot, paired-samples t-test, and annual variation were used to study the long-term impact of rehabilitation on pavement performance. According to maintenance, the results indicated that chip seal and thin overlay had the greatest impact on long-term cracking improvements such a fatigue cracking, longitudinal cracking, and transverse cracking. Long-term roughness and rutting improvements were best achieved with a thin overlay. In terms of fatigue cracking, transverse cracking, and roughness, the effectiveness of crack sealing was the worst. With respect to rehabilitation, results from the analysis showed that recycled HMA mix had no influence on transverse cracking for both thin and thick overlays. It was indicated that recycled mix had no impact on fatigue
cracking for thin overlays. As expected, the use of recycled mix was found to be effective in decreasing the rutting and roughness potential of thick overlays. The climate had no obvious impact on the development of transverse cracking while the wet climate provided higher fatigue cracking and longitudinal progress for recycled sections.