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Evaluation of Rheological Properties of Modified Binders with Two Modifiers

Jalaeian Samani, Mohammad Hanif | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42673 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Tabatabaee, Nader
  7. Abstract:
  8. Binder modification, to improve the rheological properties and meet the standard requirements, is a common practice. The modification is usually done by adding polymers like Ethylene Vinyl Acetate (EVA) and Styrene Butadiene Styrene (SBS), waste materials like crumb rubber, or acids like Poly phosphoric acid (PPA) or by air blowing techniques. High temperature rheological properties of modified binders are usually improved by using polymers while the low temperature rheological properties mostly depend on the original binder. Therefore, the rheological properties at low temperatures do not show clear improvements in the modified binder compared to the original binder. This indicates that a lot of factors are involved in modification of binders at low temperature. Most polymers improve the binder properties in the low or high temperature ranges and not both. To overcome this limitation use of binary additives were proposed in this research. Binary additives used in this research are EVA with SBS and EVA with PPA in different percentages. The complex shear modulus values of neat and modified binders, in two temperature ranges were compared together using frequency sweep test. The multiple stress creep and recovery (MSCR) test were conducted for high temperature evaluation of modified binders. The high temperature test results for modified binder with binary additives showed a better performance compared to the original binder. The performance of modified binders also depended on type and amount of modifiers. According to the Superpave and MSCR criteria at high temperatures, the binder performance became better using a higher dosage of modifiers, although both approaches did not rank the binders the same.. It is because of the inability of Superpave standard to distinguish the elastomeric polymers properties outside the linear viscoelastic range as opposed to the MSCR. Based on AASHTO standard TP70, it was also found that the amount of elastomeric polymers used in this research were not high to provide the desired elastic properties to the modified binders
  9. Keywords:
  10. Modified Bitumen ; Multi-Stress Creep and Recovery (MSCR)Test ; Frequency Sweep ; Complex Shear Modulus

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