The determination of performance grades of refinery bitumens manufactured in turkey for the use in road pavements

The performance of the road pavements which constitute a substantial amount of highway costs depends largely on the convenience of the grade of the bitumen used in hot mix asphalt (HMA) to the prevailing traffic and climatic conditions. Bitumen grading system in use in Turkey is the penetration system and the selection of the bitumen grade is done on the basis of empirical experiences. A newly developed grading system, namely SUPERPAVE binder grading system enables to test the rheological properties of binder directly related to the performance of pavements with respect to rutting at high temperatures, fatigue cracking at intermediate temperetures and thermal cracking at low temperatures. Additionally, Texas Department of Transportation developed a performance-graded binder specification for surface treatments (SPG) where different distress types such as bleeding and aggregate loss are considered. The performance grading system, in contrast to conventional grading systems, is applicable to the polimer modified bitumens as well. In the thesis, a series of tests including rotational viscosity, rolling thin film oven, pressure aging vessel, dynamic shear rheometer and bending beam rheometer tests in accordance with the requirements of SUPERPAVE binder specification was conducted on the bitumens of Kırıkkale, İzmit, Aliağa and Batman refineries processing petroleum into the bitumen in Turkey. In this way, the performance grades of the neat bitumens were determined for both hot mix asphalts and surface treatments. Furthermore, the refinery bitumens were modified with two types of polimers, SBS (styrene-butadiene-styrene) and Elvaloy and the performance grades of the modified bitumens and the extent of the performance enhancement due to modification were ascertained. Besides, extreme air and pavement temperatures (average 7 days maximum and average 1 day minimum air and pavement temperatures) for %70 and%98 reliability using the data of the meteorological weather stations in Turkey were calculated in a selected road network of total length of 11 279 km under the responsibilty of General Directorate of Turkish Highways and it was designated what performance grade has to be used and corresponding refinery bitumens.