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An Investigative Study on Iranian Bitumens Compatibility with SHRP Performance Grading System, and Production of the Needed Grades

Aflaki, Sasan | 2009

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 39482 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Tabatabaee, Nader
  7. Abstract:
  8. This investigative study intends to identify and characterize bitumen from seven Iranian bitumen production plants according to the Superpave Performance Grading (PG) system, conventional classic tests, and chemical separation tests. The study then compares the identified performance grades with the thirteen performance-grade binders required for specific climatic zones in Iran. It is observed that the variety of available binders is not adequate to fully cover the required PGs. Blending was initially considered as a suitable and economic method for production of the missing performance grades. However due to similar rheological properties of bitumen samples, resulting in nearly identical temperature susceptibility among them, a set of modifiers, as well as laboratory air blowing, were used to generate the required PG binders. The used modifiers included crumb rubber, gilsonite, polyphosphoric acid, and styrene-butadiene-styrene (SBS). Based on test results it was generally observed that: •HT improved for every modified asphalt binder used in this research. •IT and LT underwent both positive and negative changes in modified binders. •SBS modification generally improves (reduces) the S-limit temperature of the binders. In cases where the m-limit temperature controls the LT, improvement of low temperature behavior from SBS modification should not be expected. •Air blowing simulation and crumb rubber modification improved (expanded) the performance range both in the HT and LT directions. •It appears that modifications with gilsonite and PPA cause an increase in asphalt binder stiffness accompanied by IT and LT deterioration. In order to perform the required tests under standard conditions in house, a fully equipped Superpave® asphalt laboratory was set up in the department of civil engineering at Sharif University of technology, which has contributed to transfer of the engineering knowledge not only in standard experiment procedures but also in supporting ideas shaped through the development of SHRP protocol
  9. Keywords:
  10. Performance Grading ; Rheology ; Bitumen ; Bitumen Tests ; Modified Bitumen ; Bitumen Addetive

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