الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Road deterioration is a critical situation for road sector because of the high cost for construction of new roads and maintenance of existing roads and routes. Restoring serviceability of bituminous pavements has significant economic and societal benefits as the pavements plays an important role in our daily life thereby providing safe and a convenient means of transportation which is one of the major aspect of our life. However, insufficient funding often limits the timely repairs and rehabilitation of the pavements. Therefore, better funding and management should be provided in order to keep the pavements in good condition and from getting damaged due to the aforementioned distresses. This research has been undertaken to review the asphalt distresses due to type of bitumen and role of adopting viscosity grading systems and environmental effect on selection of asphalt binder Based on the results and analysis performed as apart of this thesis, the main conclusion of this study is : 1- Asphalt Binder purchasing should consider the actual stiffness difference between asphalt binders and penetration values. 2- dividing regions into temperature zones according to the PG requirements is very important to select proper type of bitumen for example : at present, commonly used grade in Pakistan is A-60/70 and K-60/70. The corresponding grades are PG 58-22 and PG 64-22 which is likely to rut in areas requiring PG 70-10. This may be one of the major reasons of premature failures especially rutting in most of our pavements 3-asphalt distresses like rutting , bleeding , fatigue cracking , raveling , happened due to use the wrong performance grade , viscosity of binder in the asphalt pavement . This study recommended to use the superpave tests to evaluate asphalt binder properties instead of traditional tests.